• ,,_,1,,¢ _

For further information regarding this report, contact Dr. Gabriel R. Wallace, Director of the Research and Technology Office, Mail Stop ER01, Marshall Space Flight Center, AL 35812. The telephone number is 205-544-4359. #A_n _>l- _o,>toqo

Research and Technology 1993

Annual Report of the Marshall Space Flight Center

(NASA-TM-I08420) RESEARCH AND N95-10021 TECHNOLSGY, 1993. SALUTE TO SKYLA_ AND SPACELAB: TWO DECADES OF _ISCOVERY Annuul Report (NASA. Unclas Marshall Space Flight Center) 230 p HI/99 0013724

NASA TM-108420

National Aeronautics and Space Administration

George C. Marshall Space Flight Center Marshall Space Flight Center, Alabama 35812

Introduction

"...both leadership in technolog4F and science and partnerships with other countries, those are the keys to our fitture as a peopl¢; to our standard of living, to our qualitv of life, as well as to our ability to continue the American tradition of exploring frontiers."

President Clinton

June 22, 1993

Twenty years ago, the challenge of putting a scientific laboratory into space led to the first Space Station--Skylab. Ten years ago, the first reusable .space-based scientific laboratory--Spacelab-- was launched aboard the Space Shuttle Columbia. On the anniversaries of these two highly successful missions, we are reminded of the numerous benefits that come from meeting such challenges. Both Skvlab and Spacelab propelled the development of new technologies to over- come the limitations imposed by gravity and by space travel. In addition to spurring new innovations, our unique view from space has given us insights into the workings of our own planet--and our place in the cosmos--that otherwise would not have been possible. The Spacelab program continues to provide a workshop for new scientific investigation and information.

From its inception, the National Aeronautics and Space Administration has invested in technological developments that have led to improvements in life on Earth, in fields ranging from aviation and agriculture, to communications and computers, to medicine. Some recent technology transfer projects, as well as possible opportunities to work with MSFC resources, are highlighted in this book.

Research and TechnoloRy 1993: Annual Report of the Marshall Space Plight Center features articles by some of the scientists and engineers who help make programs such as Ski,lab and Spacelab come alive. The diverse work that has been accom- plished over the past year continues the Center's tradition of technological innovation and scientific discovery and prepares us for whatever challenges the future may hold.

..z

T.J. Lee Director Acknowledgments

The point of contact and coordinator at MSFC for this report is H.C. Stinson (ER41/205-544-7239). She was assisted by an editorial committee consisting of G.F. McDonough, C.R. Chappell, S.H. Morgan, W.C. Snoddy, and G.R. Wallace. Detailed editorial support and production assistance was provided by MSI, a Division of The Bionetics Corporation. The research and technology work at MSFC is a cooperative effort, however, due to space restrictions, it is impossible to list all those involved in the projects described in this report.

To assist the reader, the MSFC contact, office code, and telephone number are included at the beginning of each article. The sponsoring organization and university and commercial involvement are given at the end of each article. Please note that some sponsoring organizations have implemented name changes. An abbreviations and acronyms list, an alphabetical index of contacts, and an index of key words are presented at the end of this report. Table of Contents

Salute to Skylab and Spacelab Two Decades of Discovery Michael D. Wright ix Advanced Studies

Introduction James M. McMillion

Space Science

Astrophysics--Lunar Ultraviolet Telescope Experiment Max E. Nein 2 Robert O. McBrayer Inner Magnetosphere Imager Mission C. Les Johnson 3 Carmine E. DeSanctis

Solar Ultraviolet Radiation and Correlative Emissions Joseph R. Dabbs 5 Carmine E. DeSanctis

Space Systems

Geostationary Earth Observatory Program Vernon W. Keller 6 Space Laser Energy Edward E. Montgomery 7 Space Station Advanced Programs John M. Butler, Jr. 9 Tether Applications in Space Charles C. Rupp 10 John M. Butler, Jr. A Long Duration Exposure Facility Follow-On Spacecraft Concept Vernon w. Keller 10 Small Expendable Deployer System James K. Harrison 12

Commercial Use of Space

Protein Crystal Analysis Equipment Kaye Inman 13 Kenneth R. Taylor

Transportation Systems

Access to Space: Advanced Technology Vehicle (Option 3) Focused Technology/ Advanced Development Plan Gene Austin 14

Research Programs

Introduction Gregory S. Wilson 17

Earth System Science

Numerical Modeling of Nonlinear Baroclinic Fluid Systems Timothy L. Miller 18 Diagnostics of the Global Hydrologic Cycle Franklin R. Robertson 19 Mesoscale Modeling Related to the Hydrologic Cycle William M. Lapenta 20 Lightning Radiative Transfer Inversion Studies William J. Koshak 21 Defense Meteorological Satellite Program Optical Linescan System Data System Global Survey of Lightning Steven J. Goodman 22

Global Aerosol Backscatter Experiments Maurice A. Jarzembski 24 Global Atmospheric Modeling Daniel E. Fitzjarrald 26 Spatial/Temporal Variability of Wind Fields for Design of Remote Sensors Michael Susko 27 Earth Observing System Pathfinder Passive Microwave Data Set Production H. Michael Goodman 30

III Four-Dimensional Interactive Analysis Capability Paul J. Meyer 31

Evaluation of Thermosphere Density Models Ronnie J. Suggs 32 Global Climate Monitoring from Satellites Roy W. Spencer 34 Geophysical Fluid Flow Cell Experiment Fred W. Leslie 34 The Advanced Microwave Precipitation Radiometer Robbie E. Hood 36 Multispectral Atmospheric Mapping Sensor Mark W. James 37 Multicenter Airborne Coherent Atmospheric Wind Sensor Jeffry Rothermel 38 Space Shuttle Lightning Research Otha H. Vaughan, Jr. 39 Aircraft Investigations of Lightning and Thunderstorms Richard J. Blakeslee 40 Lightning Imaging Sensor Hugh J. Christian 41 Sensor Devek)pment: Lightning Imaging Sensor Calibration Mark W. James 42 Advanced Technologies for Geostationary Orbit Remote Sensing Ronald J. Koczor 43

Space Physics

The Mechanisms of Solar Variability--A Study of the Origins of the Variability of the Solar Output John M. Davis 44 Solar Magnetic Fields Gilmer A. Gary 45 Corona and Solar Wind Ronald L. Moore 47

Long-Term Solar Activity Predictions David H. Hathaway 48 The Effect of Solar Wind Changes on the Heliospheric Termination Shock Steven T. Suess 50 Understanding the Quiet Solar Transition Region--The Source of Solar Ultraviolet Radiation James F. Dowdy, Jr. 53 Substorm-Generated Impulsive Plasma Flows Thomas E. Moore 55 Mass Spectrometer Resolution Enhancement Using an Electrostatic Lens Thomas E. Moore 57

Application of Focusing Electrostatic Mirrors to a Spaceborne Ion Mass Spectrometer Craig J. Pollock 59 The Ionosphere as an Alpha Particle Source Barbara L. Giles 62 Thomas E. Moore

Two-Dimensional Motion of Oxygen Ions in Earth's High-Latitude Ionosphere Michael O. Chandler 63 Thomas E. Moore

A Cleft Ion Fountain Model Dennis L. Gallagher 65 Minor Ion Contributions to the Ionosphere and Magnetosphere Paul D. Craven 67 The Tethered Satellite System-1 Research on Orbital Plasma Electrodynamics Investigation Nobie H. Stone 68

Application of Automated Data Acquisition to the Low-Energy Ion Facility Victoria N. Coffey 71 Enhanced Capabilities of an Electrostatic Deflection and Collimation System Nelson G. Martinez 73 Infrared Spectroscopy of the Earth's Upper Atmosphere and Planetary Atmospheres Mian M. Abbas 75

Imaging the Auroral Oval at Vacuum Ultraviolet Wavelengths Jerry K. Owens 76 Spectroscopy of the Mesosphere and Thermosphere From the Space Shuttle Jerry K. Owens 77

Astrophysics

Burst and Transient Source Experiment Observations of Gamma-Ray Bursts Gerald J. Fishman 79 X-Ray Astronomy Research Brian D. Ramsey 80 Martin C. Weisskopf The Observation of Direct Electron-Positron Pairs by Relativistic Heavy Ions in Nuclear Emulsion James H. Derrickson 81

iv Cosmic Ray Proton Spectrum Changes at 4x101_ Electronvolts Thomas A. Parnell 83

Discovery of X-Ray Nova Persei 1992 (GRO J0422+32) With the Burst and Transient Source Experiment I3. Alan Harmon 84

Infrared Space Astronomy and Space Research Charles M. Telesco 86

Microgravity Science and Applications

Electromagnetic Field Effects in Semiconductor Crystal Growth Martin P. Volz 88

Real-Time X-Ray Microscopy of Solidification Processes Peter A. Curreri 88

The Effects of Temperature on Tetragonal Lysozyme Face Growth Rates Marc L. Pusey 89

Kinetics of Diffusional Droplet Growth in a Liquid/Liquid Two-Phase System Barbara R. Facemire 90

Separation of Large DNA Molecules in Free Fluids Percy H. Rhodes 92

Highly Rarefied Solids in Microgravity: Toward the Limits for a Solid With Zero Volume and Infinite Surface Area David A. Noever 93

Technology Programs

Introduction Gabriel R. Wallace 95

Avionics

Mass Data Storage Unit Scott L. Bridge 96

Modular Software for Engine Control Charles L. Cozelos 96

Monitoring and Diagnosing the Environmental Control and Life Support System Amy N. Cardno 97 Brandon S. I)ewberry

Solid-State Coherent Doppler Lidar Michael J. Kavaya 98

Space Station Module Power Management and Distribution Automated Subsystem Bryan K. Walls 100 Norma Dugal-Whitehead

Materials and Manufacturing Processes

Hybrid Capacitive-Inductive Microsensor Arrays for Evaluating the Integrity of Thermal Barrier Coatings Samuel S. Russell 101 Shakeel S. Razvi

Formability Study of Aerospace Aluminum Alloys George E. Wertz 102

Long Duration Exposure Facility Experiments and Space Environment Effects on Materials Studies Miria M. Finckenor 104 Roger C. Linton Ann F. Whitaker

Novel Material Concepts for Spacecraft Debris Angela R. Nolen 105 James M. Zwiener

Approximation Techniques to Determine the Increase in Surface Area Due David L. Edwards 106 to Surface Roughness

Optical Effects Facility Roger C. Linton 108

Beam Processing of NARIoy-Z for Improved Microstructure, Properties, and Life Enhancement of Main Combustion Chamber Liner Biliyar N. Bhat 108

Vacuum Welding and Brazing for Space Applications Richard M. Poorman 110

Forming of Aluminum-Lithium and High Aspect Ratio Orthogrid Panels Benny F. Graham 111

New Weld Controller Nearing Completion, and Welding Pendant Incorporates New Technologies Kirby G. Lawless 112

Thermal Spray Forming of Refractory Sample Ampoule Cartridges 112 for Single Crystal Growth Space Furnaces Frank R. Zimmerman Richard M. Poorman

V New Direction in Phthalocyanine Pigments Diep V. Trinh 114 Environmental Replacement Technology: Aqueous Cleaners, Primers, and Adhesives for SRM Cases M. Louise Semmel 116 Development of an Advanced Solid Propellant Simulant M. Louise Semmel 117

Carbon Phenolic Ablative Materials Test Methodology Cindy G. Upton 118

Torch-Produced Diamond Films Floyd E. Roberts III 119 Development of Low Thermal Conductivity PAN-Based Fibers for SRM Nozzle Applications Raymond G. Clinton 120 Enhanced Aerospace Insulation Systems Edwin A. Weaver 123 Fiber Placement: New Technology for Automated Composite Manufacturing John H. Vickers 124 Environmentally Friendly Sprayable Ablator for the Solid Rocket Booster Carl N. Lester 124

Mission Operations

Virtual Reality Applications Program Joseph P. Hale II 126 A Dynamic Human-Computer Interface Prototyping Environment With Embedded Evaluation Capability Joseph P. Hale II 129

Alternative Illumination Technologies for the Human Habitation of Space Benita C. Hayes 131

Propulsion and Fluid Management

Advanced Main Combustion Chamber Development Henry J. Dennis 132 Kathy S. Tygielski Formed Platelet Combuster Liner Construction Feasibility Fred W. Braam 133 Liquid Rocket Injector Characterization John J. Hutt 133 Charles F. Schafer

Systematic Data Reconciliation in Rocket Engine Performance Predictions John P. Butas 136

High Mixture Ratio Core Gas Generator Analysis Huu P. Trinh 139 Combustion Stability Testing and Analysis Marvin Rocker 140 Low-Cost Turbomachinery Technology Matthew W. Marsh 142

Compliant Foil Bearing Technology Demonstration Gary G. Genge 143 Low-Temperature Testing of Static Seals and Leakage Characterization Edward E. Litkenhous III 144 Electromechanical Propellant Control Valve Actuator Martha B. Cash 146 High-Power Electromechanical Thrust Vector Control Actuators Rae Ann Weir 146

Multipurpose Hydrogen Test-Bed George R. Schmidt 147 Combined Foam/Multilayer Insulation Demonstration George R. Schmidt 149 Fluid Acquisition and Resupply Experiment George R. Schmidt 151 Liquid Acquisition Device Characterization George R. Schmidt 152 Magnetically Actuated Propellant Orientation George R. Schmidt 153

Structures and Dynamics

Computer Aided Grid Interface System Theodore G. Benjamin 155 Analysis of Residual Flexibility Modal Test Data Paul S. Bookout 157 Michael L. Tinker

Investigation of Inducer Cavitation and Blade Loads Wayne J. Bordelon, Jr. 159 Bosch Reaction Kinetics Research Robyn L. Carrasquillo 160 Cylinder Optimization of Rings, Skin, and Stringers Jeffery Finckenor 160 Patrick R. Rogers Neil E. Otte vi Optimum Design of Launch Vehicle Structures Donald B. Ford 163

System for Anomaly and Failure Detection Thomas H. Fox 164

Cold Air Flow Turbine Testing of Advanced Turbine Designs Stephen W. Gaddis 166

Pump Computational Fluid Dynamics Code Validation Tests Roberto Garcia 168

Hydrodynamic Design of Advanced Pump Components Roberto Garcia 169

Elastic-Plastic Fracture Mechanics Methodology for Surface Cracks M. Wayne Gregg 170

Elastic-Plastic and Fully Plastic Fatigue Crack Growth M. Wayne Gregg 171

Advancement of Volute Design Techniques Lisa W. Griffin 172

Development of Advanced Turbine Blades Lisa W. Griffin 174

Verification of Analytical Methods--Single Cycle Versus Multicycle Proof Testing Henry- M. Lee 176

Fracture Control/Damage Tolerance Methods for Composite/Anisotropic Materials Rene Ortega 176

Study of Trace Contaminant Control System Catalysts Jay L. Per W 177

Dynamic Modeling of Bearings Stephen G. Ryan 178

Porous Wall Flow Experimental Facilities Andrew W. Smith 178

Verification of Analytical Methods: NASA Crack Analysis Code Roderick Stallworth 180

Grid Optimization Tools for Complex Models Gregory R. Swanson 181 John M. Price

Combustion Chamber Analysis Code P, Kevin Tucker 182

High-Accuracy CFD Methodology for Fast Flow Transients and Nonlinear Instability Phenomena P. Kevin Tucker 183

A General Computational Fluid Dynamics Code for All Mach Numbers Ten See Wang 184

Fast Algorithm Combustion Modeling Ten See Wang 186

Hubble Space Telescope Pointing Controller Redesign Mark S. Whorton 186

Quantifying Spacecraft Crew Safety From Orbital Debris Penetration Joel E. Williamsen 187 Pedro 1. Rodriguez

Augmented Orbital Debris Shield Concepts for Space Station Critical Elements Joel E. Williamsen 187 Pedro I. Rodriguez

Systems Analysis and Integration

Autonomous Reconfigurable Navigation and Attitude Filter James J. Lomas 189

Signal Analysis and Modeling System James w. Parker 189

Thermospheric Density Variations Simulator B. Jeffrey Anderson 191

Technology Transfer 195

Abbreviations and Acronymns 199

Index of Contacts 2O3

Index of Key Words 208

vii Salute to Skylab and Spacelab ince it was established in 1960, the roots of Marshall

Space Flight Center's extensive

research and technology base

have been intertwined in the

history of thousands of space-

related projects and experiments.

Skylab and Spacelab, however,

rank among its most successfid programs. In 1993, the Marshall

Center marked the twentieth

anniversa_, of Skylab and the

tenth anniversary of the first

Spacelab mission, occasions to

reflect on the significance of these

two programs in the history of

spaceflight.

Astronaut Lousma looks homeward during a space walk outside Skylab, in orbit some 270 miles above Earth.

ix Skylab America's First Space Station

The Skylab program objectives were to prove that humans could live and work in space for extended periods, and to expand knowledge of solar astronomy and Earth resources. S_,lab's three different three-man crews spent a total of 171 days, 13 hours in Earth orbit, and performed more than 300 experiments.

The Marshall Center provided the four Saturn launch vehicles, directed many of the Skylab experiments, and devek)ped all of the major Skylab components, including the Skylab workshop. Marshall worked closely with the prime contractor for the workshop unit to convert a Saturn IVB stage into a habitable module containing crew quarters and support systems, as well as some experiment area. Marshall Center employees built portions of the Skylab Apollo Telescope Mount in-house and worked closely with several contractors on a ve W precise attitude and pointing control system. This telescope became the first manned astronomical observatory designed for solar research from Earth orbit.

The Marshall Center was also closely involved in the design, development, and test activities for the Skylab airtock module. The module was attached to the forward end of the Skylab workshop and enabled crew members to make excursions outside the space station. In addition, Marshall Center workers designed and built the structure for the multiple docking adapter. The adapter, which was attached to the forward end of the airtock module, provided the docking port for the Apollo command and service module, the spacecraft that ferried each three-member crew from Earth to the space station.

The unmanned Skylab workshop/Apollo Telescope Mount combination was launched on May 14, 1973, by the Marshall-developed Saturn V--Mnerica's most powerful rocket. Unfortunately, trout)le began approximately 63 seconds after the launch when a huge panel protecting the orbital workshop from micrometeoroids and solar radiation ripped off. Adding to the trouble, one of the solar arrays for providing power to the workshop was torn away, and a second array was only partially deployed.

All this meant one thing--the launch of the first Skylab crew, scheduled for May 15, would be delayed until methods could be devised to repair and salvage the workshop. Some troubleshooting teams at the Marshall Center and other NASA centers did not leave their posts for days. Finally, on May 25, the astronaut crew--prepared to implement NASA's plan to repair the workshop--was launched.

Skylab's telescopeslogged 8Y2 months of solar observations, compared to less than 80 hours from all natural eclipses since 1839, when photographic records were begun.

X As a result, the first Skylabmission was able to continue. The crew gathered data on some 80 percent of the planned solar experiments. They also achieved a major scientific accomplishment by monitoring a solar flare. They completed 11 of 14 planned Earth resources data runs and conducted a total of 16 medical experiments. The astronauts also gathered data from five student investigations before splashing down 28 days later, on June 22, 1973.

The second manned Skylab crew was launched on July 28, 1973. By the tenth day, the crew was devoting about 19 hours a day to scientific experiments, but a week to 10 days Astronaut Garriott operates a camera used later they were doing 27 to 30 hours of for Earth observations. (Inset) Anita was one experiments each day. Although 26 of the two spiders that flew as part of a student Earth resources experiment passes had experiment investigating the role of gravity in web making. been planned, 39 were actually accomplished. In addition, some 206 hours of solar viewing had been planned, while 305 were logged. The medical experiments had included 327 planned runs, while 333 were accomplished. The mission also included the first orbital demonstration of astronaut-maneuvering equipment and a pair of common spiders, Arabella and Anita, were on board to determine their ability to spin webs without the influence of gravity, which they did once they grew accustomed to their new evironment. The second manned Ski,lab mission ended September 25, 1973, after 59 days in space.

A Saturn IB rocket carrying the third crew lifted off November 16, 1973. The astronauts continued the Skylab in-flight experiment program, including four extravehicular activities and the observation and documentation of the newly discovered Comet Kohoutek. The third crew also served as the source for important new medical data on how humans react to weightlessness in space. The mission ended after 84 days, on February 8, 1974, setting a new endurance record and reflecting our ability to live and work in space for extended periods of time.

xi Spacelab A Short-Term Spaceborne Laboratory

As space shuttle development began at the Marshall Center in the 1970's, planners at the Center were studying ways to use the proposed new vehicle's capabilities for scientific research. Early studies at the Marshall Center had called for the development of a versatile, reusable laboratory facility. This facility would fit inside the payload bay of the shuttle orbiter and provide the crew of career astronauts (mission specialists) and members of the science community (payload specialists) with workbench space, power, computer support, and racks and storage for experiment equipment. The ninth flight of the shuttle, launched on November 28, 1983, carried Spacelab--a multiconfiguration spaceborne scientific laboratory--into orbit.

In 1970, the Marshall Center had requested proposals from industry for the preliminary design of a research and applications module as a way to provide versatile laborator/ facilities for Earth-orbital research and applications work. In 1971, the Marshall Center began in-house studies on a laboratory called the Sortie Can, later renamed the Sortie Lab. The Sortie concept for Spacelab included a combination of habitable, pressurized modules in which scientists could conduct investigations and unpressurized pallets for instrunlents requiring direct exposure to space, such as telescopes.

In 1972, NASA began negotiations with the European Space Research Organization, the forerunner of the European Space Agency (ESA). This ultimately led to an agreement between NASA and ESA, with ESA assuming responsibility for funding, developing, and building Spacelab. Under this arrangement, Marshall Center did the feasibility and preliminary design work during the Sortie studies, and ESA did the engineering design and hardware development based on Marshall-defined requirements. Marshall, however, retained responsibility for technical and programmatic monitoring of Spacelab development activities, which involved 50 manufacturing firms in 10 European countries.

In addition to program management responsibilities, Marshall Center built related Spacelab flight components, including an optical window for scientific observations, and developed a pressurized transfer tunnel for passage of crew and equipment between the shuttle's orbiter cabin and the laboratory module, where astronauts and scientists could work in a shirt-sleeves environment.

The Marshall Center also was responsible for Spacelab's command-and-data- management subsystem and its high- data-rate multiplexer and recorder. In addition, a software development facility was established to develop and verify programs for Spacelab experiment components. Other contributions ranged Flight controllersand experiment scientisits direct from the development of ground support Spacelab science activities from the Marshall equipment to sophisticated scientific Center. instruments. xii TheSpacelabprogramalsorequiredengineersandotherspecialistsattheMarshallCenter to performsystemsanalyses,designanddevelopintegrationhardware,overseeassembly and checkout,plan the flight timeline,conductsimulationand training exercises,and provide real-timesupportfor the missions.Marshall'sPayloadCrewTrainingComplex becameatrainingsitefor Spacelabmissionspecialistsfromtheastronautcorpsandpayload specialistsfrom thescientificcommunity.Priorto theestablishmentof theMarshallCenter SpacelabMissionOperationsControlCenterfacility,Marshallmissionmanagersmonitored, controlled,anddirectedexperimentsaboardSpacelabfrom theJohnsonSpaceCenter.

Theprimarypurposeof thefirstSpacelabmissionwastodemonstratethescientificcapability of thelaboratoryandto checkthethousandsof structural,mechanical,andelectronicparts makingup the laboratory.During the 10-daymission,thesciencecrew conductedmore than 70 separateinvestigationsin life sciences,atmosphericphysics,Earthobservations, astronomy,solarphysics,spaceplasmaphysics,and materialsscienceand technology. Spacelab-1wasa truly internationalmission,with 14countriesparticipating.

NumerousMarshall-developedand managedexperimentsand investigationswere on board.The ImagingSpectrometricObservatorywas amongthe atmosphericand Earth observationexperimentson Spacelab-1.It wasdesignedto providenew insightsinto the variedreactionsand energytransferprocesses that occur in the Earth'senvironment.Another experiment,theSpaceExperimentswith Particle Accelerators,was amongthe investigationsin spaceplasmaphysicsandwasdesignedto carry outactiveandinteractiveexperimentson andin the Earth's ionosphere and magnetosphere. AtmosphericEmissionPhotometricImaging, anotherspaceplasmaphysicsexperiment,was usedtoobservefaintopticalemissionsassociated with naturalandartificiallyinducedphenomena in theupperatmosphere.

Prior to the first Spacelabmission, the Far UltravioletSpaceTelescope(FAUST),acompact, wide-field-of-viewinstrument,had been used on rocketsfor brief astronomicalobservations. FAUST,however,wasusedon thefirstSpacelab missionto observegalaxiesandquasars,andfor jointobservationswith Spacelab-1experiments. An investigationin materialssciencewascalled How the body reacts to weightlessness TribologicalExperimentsin Zero Gravity and may provide clues to diseases on Earth. wasdesignedto observewettingandspreading Here Spacelab-1 payload specialist phenomenaandfluiddistributionpatternswithout Merbold exercises on orbit, while instru- the interferenceof gravity. ments measure his heart's performance.

°°. Xlll \

___,_i_ ¸__ Both Skylab and Spacelab-1 added new dimensions to the

Marshall Center research and

technology base. They left a legacy

that opened up the field of scientific

study in microgravity, where

underlying physical properties and

phenomena may be observed free

from the masking effects of gravity.

Information gained from Earth and celestial observations made from

space have virtually rewritten textbooks and, in turn, opened up

% new fields of study. Skylab and

Spacelab- I helped identify and

develop ideas and tools that would

lead to improvements in research

facilities in space, as well as contribute to the quality of life on Earth.

Michael D. Wright/CN22 MSFC Historian 205-544--6840

\

A land of glaciers is one of countless images taken from space that have enhanced map making and navigation, assisted weather forecasting, and revealed natural resources on our planet.

XV

Research and Technology 1993

III I l Space Science

Astrophysics--Lunar The Lunar Ultraviolet Telescope has The LUTE technical concept is being Ultraviolet Telescope been proposed by principal investi- analyzed and engineered by MSFC. gator Dr. John McGraw of the Uni- Because of the expense of lunar Experiment versity of New Mexico as an early, payload transportation systems, it is low-cost precursor experiment to important that the LUTE be designed Max E. Nein/PS02 future lunar observatories. The Lunar as a lightweight flight experiment. 205-544-0619 Ultraviolet Telescope, with its fast This requires that weights for sub- Robe_ O. McBrayer/PS02 optical system (f/3), is a scientifically systems--such as the optics, commu- 205-544-1926 important UV telescope that can im- nications, and data handling--and age a strip of the sky in the 0.1 to power are stringently controlled. A small ultraviolet (UV) telescope 0.35 btm wavelength regime. At the has been identified by NASA's Office orbit of the Moon, the geocorona of Space Science (OSS) as a potential effect that obscures measurements in first step in the return of NASA astron- the Lyman-alpha radiation range is omy missions to the Moon. The minimized in comparison to the LUTE will use a 1-m UV telescope situation in Earth orbit. Dr. Jack Burns that can be emplaced on the lunar of New Mexico State University is surface by an unmanned lunar lander designing the Lunar Environmental with a payload capacity of approxi- Measurement package. mately 400 kg. Typical lander con- High-Gain Antenna figurations have been analyzed by NASA. The Russian Space Agency's Phobos lander is a candidate to be used for this type of payload. ElectronicsBox The Lunar Ultraviolet Telescope is a simple, self-sufficient, transit tele- scope that achieves a wide field of _ermoelectric view (FOV) with a compact optical Generato_ system using lightweight mirrors (fig. 1). The focal plane instrument is a two-dimensional (2-D) mosaic of charge coupled devices (CCD's) arranged to cover the 1.4-degree AzimuthRingJ FOV. The Lunar Ultraviolet Tele- scope will not track specific targets, but rather points continuously at Hyperg01k Propellant a specified declination. It requires Tank no adjustment after its initial align- ment, relying on the very stable motion of the Moon to sweep out its observational swath across the sky. FIGURE1.--The 1-m Lunar Ultraviolet Telescope.

2 Advanced Studies

A radioisotope thermoelectric gen- Inner Magnetosphere image the inner magnetosphere, erator (RTG) is necessary for electri- Imager Mission combined with internal measure- cal component survival during the ments conducted previously and lunar night and for operation planned as a part of the International C. tesJohnson/PS02 throughout the lunar day-night Solar Terrestrial Physics Program, 205-544-0614 cycles. An RTG for power generation will significantly enhance understand- is ideally suited because components Carmine E. DeSanctis/PS02 ing of magnetospheric processes. and subsystem temperatures can be 205-544-0618 Techniques to allow satellite imaging maintained at a tolerable level during of important charged-particle popu- the lunar night when temperatures In 1991, MSFC initiated a design lations in the magnetosphere have drop to near 60 K, while keeping study for a mission to globally image recently been demonstrated. Tech- systems weight at a level commen- the Earth's magnetosphere from niques to image the ring current with surate with a photovoltaic power space. The IMI mission, which is scheduled to launch before the end energetic neutral atoms are being system. Trade studies of the LUTE optimized for space satellite use. The subsystems are now being com- of the decade, will obtain the first imaging of low-energy magneto- pleted to optimize the design, to simultaneous images of component spheric plasmas using solar radiation select the best lunar site for telescope regions of the inner magnetosphere using extreme and far ultraviolet resonantly scattered from singly ion- placement, and to identify interfaces ized helium (He*) has also been dem- light, x rays, and energetic neutral with potential lunar transportation onstrated. Singly ionized oxygen (O +) systems. atoms. Working with the NASA Headquarters-appointed science imaging of the plasmasphere and ex- tended imaging of the near-Earth Deployment of the LUTE on the working group, the MSFC Program Development engineering design plasma sheet also appear to be Moon during this decade is techni- feasible. cally and programmatically feasible. team is near completion of the mission Phase A study. Although this constitutes a tight The baseline IMI mission calls for an schedule, plans are being made to Progress in magnetospheric physics instrument complement of seven reduce the historically lengthy re- has shown that a static model built imagers to be flown on a spin-stabi- view phases occurring in the devel- up over time from single-point par- lized spacecraft in an elliptical Earth opment of flight systems through the ticle and field measurements alone orbit with an apogee of seven Earth introduction of new ways of doing cannot adequately describe the com- radii, perigee of 4,800 km, and a business. Typically, this approach is plexity of the Earth's magnetospheric 90-degree inclination. The strawman based on concurrent engineering and system. Further progress is contin- instruments, with a brief summary of maximum use of computer aided gent upon global observations of their measurement characteristics, are design (CAD). the entire system. A program to listed in table 1.

SlmtX_oP Office of Space Science rmtE 1.--Strawman instruments for the baseline IMI mission spacecraft

University Involvement: University of New Mexico and New Mexico State University HotPlasmaImagers EnergeticneuralatomswithenergiesbetweenI toSO,O00and20,000to 1,000,000eV

He+304PlasrnasphereImoger Singlyionizedheliumwith304/_light

0+834PlosmaspbereImnger SinglyJonizedoxygenwith834Alight

GeocomnalImager Ughtwithawavelengthof1,216A

AuroralImager Ughtwithwavelengthsof1,304and1,356A

ProtonAuroralImoger Ughtwithawavelengthof1,216

ElectronPrecipitationImnger XrayswithenergJesofbetween300and10,000eV

3 Research and Technology 1993

ProtonAuroraImager I_'_'0n Geacoroeal HotPlasmaImager AuroralImoger(FUV) Precipitation Imager (LowEnergyHead) Imagec Panel

Imager (HE+3O4) SpacecraftSubsystems Commandand DataHandling,Attitude ControlSystem,

SolarPanel HotPlosmaImoger (HighEnergyHead) PropulsionModule

Plosmosphore Star17Apogee Imager(0÷834) KickMotor !1wee-Axis-Stal_izedSpacecraft Spin-StabilizedS_aft

I:fGUeE2.--IMI dual spacecraft option.

Several spacecraft concepts have The IMI mission will enhance our terrestrial and celestial plasmas will been thoroughly examined for the understanding of the near-Earth be imaged and understood in that mission. The baseline concept is a space environment and the coupling context--not utilizing in situ particle single spin-stabilized spacecraft with of this environment to the Sun. The and field measurements as were a despun platform. The 1,300 kg mission instruments will drive the required previously. spacecraft would be launched by a development of high-throughput, Delta II launch vehicle from the narrow bandwidth ultraviolet filters, Inner Magnetosphere Imager Scientific Western Test Range (Vandenberg Air high-reflectivity mirrors, and software Rationale and Mission Concept. Force Base, CA) and perform on useful in low signal-to-noise optical Vol. 1: Executive Summary. 1991. NASA, MSFC, AL. orbit for 2 yr. The spacecraft would image processing. The technology use body-mounted solar arrays to developed for imaging the hot Johnson, C.L., and Hermann, M. 1993. provide the 325 W of mission power plasma with energetic neutral atoms The Inner Magnetosphere Imager and communicate the 59 kb/s data will enhance scientists' basic under- Mission. Society of Photo-Optical rate to the ground via the Deep standing of thin-foil scattering and Instrumentation Engineers (SPIE) Space Network. An optional configu- low-energy particle optics. The tech- Aerospace Science and Sensing, ration would divide the science nology developed for the IMI could Orlando, FL. instruments onto two smaller space- have immediate spinoffs to other craft. The first would be a small spin- scientific applications, as well as the Wilson, G.R. 1993. Inner Magnetosphere Imager (IMI) Instrument Heritage. stabilized spacecraft carrying the commercial optics industry. Contractor Report 4498. NASA, instruments borne by the spinning MSFC, AL. portion of the baseline concept. The The scientific return from the IMI second would be a three-axis-stabi- mission will open a new window on Sponsor: Office of Space Science, lized spacecraft carrying those instru- the plasma universe, providing a Space Physics Division ments from the despun platform that better understanding of the magneto- require precise pointing to specific spheric plasmas in the near-Earth regions of the magnetosphere. These environment, as well as those deep- two spacecraft options are illustrated space plasmas not previously mea- in figure 2. surable from the Earth. Such

4 Advanced Studies

Solar Ultraviolet SOURCE utilizes a mix of highly the use of small spacecraft and low- Radiation and Correlative stable instruments and calibration cost launch vehicles of existing design. Strawman instrument com- Emissions techniques to obtain accurate mea- surements in a spectral range where plements of 55-kg mass have been detector drift and degradation tends defined that meet the scientific goals Joseph R. Dabbs/PS02 to be severe. SOURCE instrumenta- and are compatible with "Lite Sat" 205-544-0623 tion consists of spectroradiometric type spacecraft in Sun-synchronous orbit at 400 kin, which is reachable Carmine E. DeSanctis/PS02 instruments and imagers that mea- 205-544-0618 sure emissions from the solar chro- with small expendable launch ve- mosphere, solar transition region, hicles such as the Pegasus or The SOURCE mission will give an and corona. Spatial resolution of Conestoga. 5 arc seconds (or better) is desired. accurate measurement of the ex- Current activi W has focused on treme ultraviolet (EUV) solar flux The strawman payload that has been redefining and reducing the comple- from 1 to 122 nm. The EUV flux is considered has a mass of 55 kg and ment of instruments that will guaran- required as an input to models of the requires approximately 100 W of tee the required accuracy at a cost Earth's atmosphere. In addition, the electrical power and a telemetry rate compatible with the Small Explorer of 400 kb (or less). EUV flux data will complement and program constraints. help explain the data from other satellite missions such as the Upper The main goal of the SOURCE mission Sponsor: Office of Space Science Atmosphere Research Satellite is to develop proxy measurements (UARS); Thermosphere, Ionosphere, that indicate solar activity of the Mesosphere, Electro-Dynamics same type that produces EUV radia- (TIMED) Mission; and so forth. Fi- tion, but are in spectral regions that nally, the SOURCE data will help to can be monitored from ground- develop proxy measurements that based instruments. The data from can be used to accurately predict SOURCE are extremely important, ELIV flux when direct measurements and it is possible to accomplish these are not available. goals in an economical manner by

5 Research and Technology 1993 III I II Space Systems

Geostationary Earth integration times and improved characteristics, is important to meet Observatory Program sensing efficiency, but places in- the new requirements. Silicon creased thermal demands on the carbide's (SiC's) inherent properties spacecraft and its sensors, as well Vernon W. Keller/PS02 of high-stiffness-to-weight, very high 205-544-2470 as more complex pointing control thermal stability over wide tempera- than is required with spin-stabilized ture excursions, excellent optical satellites. This severe thermal envi- The Geostationary Earth Observatories polish capability, and projected low are a future element of NASA's Mis- ronment is even more of a problem cost make it an ideal candidate. A because the instrument optical sion to Planet Earth program. They prototype 0.5-m diameter f/4 tele- systems are simultaneously being will provide the excellent temporal scope that uses SiC for both optics designed for high-spatial and high- resolution measurements required to and structure is currently being de- spectral resolution. For example, complement the other MTPE space signed, developed, and performance observations. meteorological imagers in the past tested over a wide temperature have typically had a visible channel range. This effort is scheduled for ground resolution of about 1 km in completion in late 1994. The GEO element of MTPE is currently both low-Earth and geostationary in the concept definition stage orbits. This corresponds to about (Phase A). Based on the science Advances not only in optics, but also 1.3 mrad in low orbit and 28 grad in in structures, detectors, coolers, coat- requirements for the mission, a pre- geostationary orbit. One of the pro- ings, pointing and control systems, liminary GEO remote sensing instru- posed new GEO imagers requires and calibration technologies would ment complement has been defined. lO0-m ground resolution in several significantly benefit the GEO pro- These instruments include optical visible and UV spectral bands. gram. Technologies of particular imagers, atmospheric sounders, pas- interest include: diffractive optics, sive microwave sensors, and other To achieve such high performance, tunable liquid-crystal optics, ther- passive sensors that require either the new GEO instruments will need mally stable optical coatings, infrared excellent Earth viewing temporal to incorporate technological advances (IR) etalon interferometers, compos- resolution, or other attributes such beyond those used in current civilian ite reflective elements, image motion as the nearly continuous view of the designs. For example, since the im- compensation, and solar channel Sun (annually, 99 percent of the ager telescope structure and optical calibrators. time), best attained from geostationary elements such as the mirrors, which orbit. are exposed most directly to solar Koczor, R.J. 1993. Technology Needs for illumination, can undergo a tempera- Geostationary Remote Sensors. SPIE Studies are addressing both the ture change on a three-axis-stabilized 1952-15. Orlando, FL. instrument design and the spacecraft spacecraft from -10 to +70 °C in required to accommodate them. a period of a few hours, use of mate- Sponsor: Office of Mission to Planet Utilization of three-axis-stabilized rials that exhibit high thermal stabil- Earth spacecraft instead of "spinners" ity, as well as good structural and permits longer Earth viewing optical performance and lightweight

6 Advanced Studies

Space Laser Energy

Edward E. Montgomery/PS04 205-544-1767 I Wireless power transmission research at MSFC is directed toward develop- ing critical component technologies for the SELENE power beaming pro- gram. The objective of SELENE is to develop and demonstrate technolo- gies needed for low-cost, reliable electrical power and propulsion for spacecraft, based on the principle of photovoltaic conversion of high- power laser light to electricity. It is a ground-to-space system utilizing near-visible wavelength technologies under development by NASA. The focus on the development of key component technologies in adaptive optics and high-energy lasers has re- FICURE3.--Active mirror segment prototype design for an atmosphere suited in several prototype hardware compensation beam director. items over the last year.

The two main subsystems of a laser form a 1.5 MeV electron beam Several type I segment assembly power beaming ground station will source. The development of this prototypes were developed based on be a free electron laser (FEL) as a system was a jointly funded project piezoelectric, electrostrictive, and generator and a large segmented by NASA and the U.S. Navy. electromagnetic actuators. Figure 3 adaptive beam director that functions contains a photograph of a com- as the transmitter. Their key tech- In the beam director development pleted type I segment with an nologies were identified in reviewing program, MSFC has concentrated on electrostrictive actuator. Most of the cost goals set down for the first developing the active mirror seg- type I segments designed and built ground site. In the laser, the highest ments that will populate the primary this year were based on the type I leverage potential was shown to be mirror of the SELENE Cassegrain design concept (Montgomery et al. in the accelerator cost. For the beam telescope configuration. A critical 1993). In the type I system, an exter- director, the major driver was the issue to be addressed in the design is nally located wavefront sensor deter- segmented primary mirror. the quality and economy in mass mines the aberration pattern in the The performance of an innovative production of the small-scale (3 cm atmosphere. That information is fed induction linear accelerator module fiat-to-fiat), hexagonal, low figure to a processor that contains the con- design constructed by Science Re- error, mirror segments with embedded trol algorithm and produces the search Laboratories has been tested. actuators sensors and electronics. commands for the segment actuators. Recently, this 1.0 MeV first accelera- Another issue is the ability of a The SELENE design team originated tor section was installed on the controller to manage the dynamics of an innovative concept this year in beamline with an injector section to a multitude of simultaneous channels. which the wavefront sensor is an

7 Research and Technology 1993

batch sterilization of medical supplies using the accelerator module tech- nologies. The atmosphere compensa- tion capability achieved through the active segments will be applicable to all ground-based telescopes and future space telescopes as well. Po- tential applications for the high- power laser component include repair of the ozone layer and re- moval of orbital debris.

Meulenberg, A. July 1992. Application of Laser Power Beaming to Commercial Communications Satellites. Proceed- ings of the SELENE Advocacy Briefing and Progress Review. NASA, MSFC, AL.

Montgomery, E.E.; Fawcett, S.C.; Redmon, J.W., Jr.; and Lindner, J.L. February 1993. SELENE Component Technology Test-Beds at MSFC. First Annual Wireless Power Transmission FIGURE4.--Innovative active mirror segment concept Conference Proceedings, Center for utilizing an integral wavefront sensor. Space Power. College Station, TX. Rather, J.D.G. July 16, 1992. Laser Power integral part of each segment. These in the total life of a satellite Beaming for Space Development: An type II segments also include a sec- (Meulenberg 1992). Assuming the Example of an Ongoing Advanced ond solid Cassegrain reflector ele- typical 24 transponders per satellite, Research Technology Project at ment and a CCD camera. Figure 4 current market rate for feed time, NASA. Proceedings of the SELENE shows the prototype constructed and a group of 22 satellites specifi- Advocacy Briefing and Progress Review. NASA, MSFC, AL. using piezoelectric actuators. cally identified for this service, there is a potential revenue stream of ap- Sponsor: Office of Advanced The benefits of a laser power beam- proximately $500 million per year. Concepts and Technology ing system include extensions in the Commercial Involvement: Science life of existing geostationary satellites Other applications include weight by reducing battery discharge during reductions in the power systems for Research Laboratories; Comsat, Inc.; the relatively short but frequent peri- future satellites and spacecraft. Kaman Corp.; Forth, Inc.; AVX, Inc.; ods that they are in the Earth's Highly efficient electric propulsion Shaeffer Magnetics, Inc.; and United shadow and unable to use solar systems for orbital transfer vehicles Applied Technologies, Inc. arrays. Studies by Comsat, Inc., indi- would be possible. Spinoff benefits cate a potential 20-percent extension include waste treatment and large

8 Advanced Studies

Space Station Advanced Strongbacks add weight, but minimize Cryo Programs impacts to existing carriers and also DryCargo*"_,-._,__,\_'--"_ Carrier allow more logistics elements to be Carrier carried. Some strongback concepts John M. Butler, Jr./PS04 allow elimination of the carriers, with 205-544-4833 the orbital replacement units being mounted directly on the strongbacks. Strongback During 1993, MSFC continued studies of advanced concepts related to the Orbiter BayAnalogueStrongbock Engineering prototype development evolution of the space station. The Strongback 1993 effort involved assessment of work continued during 1993 in: (1) the Environmental Control and logistics elements, including the ability of such elements to be accom- Life Support System (ECLSS) Ad- modated on expendable launch vanced Automation Project (AAP), vehicles (ELV's). Current designs of and (2) the Space Station Module DryCargo space station logistics elements were Power Management and Distribution examined to determine their poten- (SSM/PMAD) system. Carrier TriangularStroogbock tial usability on ELV's. Several types Cryo The ECLSS AAP work was coordi- of mounting locations and arrange- Carrier ments for logistics carriers on nated closely with the Space Station ELV's were investigated, including: Control Center Complex personnel (1) cantilevered concepts (fig. 5), this year, to facilitate implementation and (2) concepts utilizing strongbacks of this technology. Models of the that provide carrier interfaces analo- Carbon Dioxide Removal Assembly DryCargo gous to those in the space shuttle (CDRA) and the Temperature and Carrier Strongback orbiter payload bay (fig. 6). Cantile- Humidity Control (THC) system have CruciformStrongback vered concepts require some degree been developed and are being of structural modification to existing assessed by the control center FtOURE6.--Strongback carrier carriers; these were identified. engineers. concepts.

The approaches and techniques proved in the SSM/PMAD test-bed system are now being integrated into the Electrical Power System (EPS) console software for the Johnson / Space Center (JSC) Consolidated ModifiedIntograled Control Center. Developed in coop- PressurizedLogistics eration with the Lewis Research Modu_{PtM} ModifiedIntegrated UnpressurizedLogistics Center (LeRC) and controllers at the Carrier(ULC) Kennedy Space Center (KSC), an EPS

RingAdapter---_ RingAdapter console using these technologies is expected to enable better, less ex- pensive operations than do current techniques.

CargoTransfer CTV Sponsor: Space Station Engineering Vehicle(CW} Division

FIGURE5.--Cantilevered carrier concepts.

9 Research and Technology 1993

Tether Applications in 1994, will demonstrate a dosed- A Long Duration in Space loop control law to deploy the tether Exposure Facility system in a stable local-vertical Follow-On Spacecraft orientation. A third SEDS flight is Charles C. Rupp/PS02 planned to boost and release a stu- Concept 205-544-0627 dent-developed satellite known as John M. Butler, Jr./PS04 the Students for the Exploration and Vernon W. Keller/PS02 205-544-4833 Development of Space Satellite 205-544-2470 (SEDSAT) to a higher orbit than that Research into tether applications in attained by the launch vehicle. The successful flight, retrieval, and space has the objective to develop Analysis of data from the first SEDS analyses of the Long Duration Expo- the use of tethers in a broad range of flight is leading to improved models sure Facility experiments have dem- space activities. NASA's first tether of the SEDS deployment friction and onstrated the value of long-duration systems flew on Gemini 12 and 13 in to the development of closed-loop space exposure for a broad spectrum the late 1960's, which demonstrated control laws for these future missions. of science and engineering investiga- spin-stabilized and gravity-gradient- tions. The original LDEF was an stabilized configurations of the Potential scientific applications for excellent gravity-gradient spacecraft, Gemini manned spacecraft and the tethers in the near future include but because of its 9-m length and Agena docking target. the use of two SEDS-type deployers 9,700-kg mass, it was difficult to on a single spacecraft to deploy a manifest on the space shuttle in The first of the modern tethers, the dipole antenna for low-frequency conjunction with other payloads for Tethered Satellite System (TSS), flew either launch or retrieval. communications system research. on the space shuttle in 1992, and Other applications being studied demonstrated the electrodynamic include the use of a SEDS to deorbit An LDEF follow-on spacecraft-- interaction of a tether system with LDEF II--has been conceptualized commercial payloads and to suspend the environment, and tether deploy- (fig. 7). Its short stowed length payloads downward for atmospheric ment and retrieval, as well as con- research. Potential uses of tethers for (-3 m) greatly improves shuttle tributed to an understanding of manifesting opportunities, while still transportation include deorbiting tether dynamics, particularly in prox- providing very large surface area waste from the space station and imity operations with the shuttle. The exposure for experiments. Deploy- deorbiting spent rocket upper stages second modern tether system, the able "wings" on each end of the to control the rising debris hazard to short, cylindrical main body of this Small Expendable Deployer System operational spacecraft. (SEDS), flew in March 1993, as a new spacecraft provide the means secondary payload on an Air Force for gravity-gradient stabilization Delta rocket, and demonstrated the Early in 1993, a nonadvocacy panel while greatly increasing the space- low-tension deployment profile and reviewed the TSS and SEDS flight craft surface area. The center section the capability of a tether system to results and the studies and plans for of the spacecraft is oriented with the deorbit payloads from low-Earth future tether applications. The panel end faces of the 12-sided, 4.3-m- orbit. A third tether system, the findings favored a reflight of the TSS diameter cylinder perpendicular to Plasma/Motor Generator (PMG), flew and more frequent SEDS flights. the velocity vector, thus providing in June 1993, from another Air Force Additional coordination with poten- large areas for experiments in both tial user communities is recom- Delta rocket, and demonstrated the the ram and anti-ram directions, as mended to disseminate information use of plasma contactors to enhance well as additional exposure area on the beneficial uses of tethers. the electrical contact of the tether around the periphery of the cylinder. system to the plasma. When deployed and properly ori- Sponsor: Office of Space Systems ented with the shuttle's remote ma- Planning and engineering support Development, Advanced Programs nipulator system (RMS), both wings continue for follow-on SEDS mis- of the spacecraft are oriented edge- sions. SEDS-2, scheduled for flight on to the direction of motion and lie

10 Advanced Studies

PowerTransferredviaRMSto DeployWings i i LDEFRMSRemovesII PlacedinLDEFhoperIIFromAttitudeCargoandBayReleased

FIGURE8.--LDEF II spacecraft deployment sequence.

Flat surfaces mounted normal to, and government, academia, and industry. on the periphery of, the wings pro- In-house design, construction, and vide additional areas in both the ram integration of the spacecraft will FIGURE7.--LDEF II concept. and anti-ram directions for cosmic provide valuable hands-on experi- dust, micrometeoroid, and orbital ence for a number of young NASA debris collection experiments, free of engineers. After exposure to the low- in the plane that contains the local contamination from splatter off sec- Earth orbit (LEO) space environment gravity (g) vector (fig. 8). Each of the ondary surfaces. for approximately 3 yr, this free-flyer relatively thin wings readily accom- spacecraft will be retrieved by the modates dual side exposure of heavy The baseline spacecraft concept space shuttle and the experiments nuclei collector (HNC) glass plate provides enhancements not available will be removed and returned to the stacks for cosmic ray detection. This on the original LDEF, such as solar- PI's for analyses and publication of is important since the HNC experi- array-generated electrical power and results. ment requires a large surface area data telemetry. As presently envi- and is quite heavy. Space environ- sioned and costed, this relatively Sponsor: Program I)evelopment mental effects experiments (materi- inexpensive spacecraft will be an als, systems, biology, microgravity, MSFC in-house-developed carrier etc.) can be accommodated on the with experiments supplied by vari- center section of the spacecraft. ous principal investigators (PI's) from

11 Research and Technology 1993

Small Expendable DeltaII Launch Deployer System Directi_ Antenna

James K. Harrison/FA34 Brake/CutterAssembly 205-544-0629 (0.9kg--16.5x 7.6x6.6an) (26kg--20x33x41 an)

The Small Expendable Deployer System is a lightweight, spinning- ElectronicsBox reel-type system designed to deploy (3kg--13x8.3x29 anl a payload attached to the end of a 20-km-long tether, which is cut and Broke/Tensiometer discarded after use. The key objec- Cable tives are to validate the design con- DeltaII Se(ond cept and study the dynamics of the StageGuidance tether during and after deployment. SectionSkin SEDS weighs about 41 kg, including the tether weight of 7 kg. The tether CanisterCable TethedConister is made from a high-strength, low- (10kg--36x25 an dial density polyethylene fiber called

SPECTRA TM. SEDS-1 flew on a Delta II launch vehicle in March 1993. CoreCable I OverallOverallSizeWe_ht= 0.6x0.6= 41 kg I SEDS-2 is scheduled to fly in 1994.

During flight, the 26-kg payload is FIGURE9.--SEDS-2 to be flown on a Delta II launch vehicle, deployed toward Earth (fig. 9). Payload instruments are an acceler- ometer, a tensiometer, and a magnet- Numerous future tether applications 680 by 792 km. Another use of SEDS ()meter (for orientation information). of SEDS are being considered. One will be to place instruments in the The SEDS-1 experiment lasted about is the routine deorbiting of the space 90- to 120-km altitude region for 2 h, ending when the tether was station waste materials, packaged in upper atmospheric research. fully deployed. The tether was cut, small, lightweight containers that can allowing it and the payload to reen- be folded for easy storage during Sponsom Office of Space Systems ter the Earth's atmosphere. On space shuttle trips to the station. Development SEDS-2, the tether will remain at- Another is the boosting of small tached to the Delta II second stage payloads such as the University of and will reenter the atmosphere, Alabama in Huntsville student-built along with the second stage, about satellite called SEDSAT to higher a month after launch. orbits--from 185 by 740 km to

12 Advanced Studies

Commercial Use of Space IIIII

Protein Crystal Analysis The study concluded that a protein Equipment cwstallographic imaging system, suitat)le to the constraints of space- based operation, is feasible. The Kaye Inman/PS05 maior tccimological innovation 205-544-2229 required is the development of a Kenneth R. Taylor/PS05 compact, low-power x-ray generator 205-544-0640 combined with efficient x-ray optics. Recent work in grazing incidence Protein er-ystal growth in microgravity optics indicates that substantial im- is one of the more pr()mising com- provement of the optical efficiency mercial uses of the space environ- of the x-ray collimating optics is ment. Protein crystals grown on the possible by combining these optics space shuttle are more defect-free with an improved n3icrofocus x-ra}' and larger than those grown in tube having a smaller emitting area. ground-based laboratories due to the if the space station experiments absence of gravity-driven sedimenta- FIGURE lO.--Laue diffraction pattern power budget can be met. The tion. Evidence to date indicates that of the enzyme protein next logical step is to build and cwstals are degraded if subjected to crystal lysozome in a test a prototype system, including a the gravity" R)rce of reent W or if there quartz capillary. 2,000 by 2,000 pixel solid-state x-my arc" relatively t()ng intervals between camera for acquiring and digitizing shuttle visits to the space station. the diffraction images (fig. 10) ac- At the 1993 CD'stallography S<)ciety For this reason, x-ray diffraction quired with this type of CCI) camera. meeting, approximately 1,000 attend- measurements made on orbit will ees exhibited considerable int_:rest in significantly improve the scientific replacing photographic fihn and In addition to the space station, there knowledge that can he gained from is a substantial dual-use commercial single-point x-ray detectors with this microgravity-grown protein crystals. type of digital x-ray imaging camera. market for both the high-efficiency The more efficient x-ray source will This Phase I Small Businesslnnovation x-ray source and the solid-state digi- make the crystallography lalxmttories Research (SBIR) study addressed the tal x-ray camera system being devel- more competitive with the synchro- feasibility of an on-orbit x-ray crystal oped under this program. The x-ray tron x-ray facilities, a real incentive diffraction imaging system, provid- generator and CCD camera would to upgrade the current x-my equip- ing on-orbit protein crystal diffrac- have immediate benefits for conven- ment in these ntlll/er()tls academic tion imaging and data acquisition, tional ground-based protein diffrac- and industrial laboratories. given the space station power, vol- tion, since use of these components ume, and weight constraints, and would considerably advance the the radiation environment in orbit. state of the art as it is now practiced Sponsor: Office of Advanced Con- An analysis of the interaction of on the ground. Even if crystallography cepts and Technology, Small lkisi- ness Innovation Research Program unshieldable cosmic rays and protons in space were deferred, development with the x-ray detector found that of the high-efficiency x-ray tube, Commercial Involvement: a pulsed operating mode would x-ray collimator, and camera can be Princeton Scientific Instruments reduce the background signal in justified for the immediate benefits the diffraction image data to an they would confer upon the large insignificant level. x-ray crystallographic community.

13 Research and Technology 1993 III I II Transportation Systems

Access to Space: same emphasis. The target for the processing and fabrication; and Advanced Technology development of this plan is technol- the design, fabrication, and ogy maturity by the year 2000. analysis of a large-scale cryo- Vehicle (Option 3) genic tank system (including Focused Technology/ The advanced technology vehicle structural and thermal cycling). Advanced Development configurations assessed consist of the Plan following general types: Vehicle Health Management and Monitoring: Vehicle health man- • Single-stage4o-orbit: all rocket agement and monitoring, while Gene Austin/PT01 (SSTO R) 205-544-0633 successfully and widely utilized • Single-stage-to-orbit: air breath- on high-performance military and commercial aircraft, is not as This focused technology/advanced ing plus rocket (SSTO A/R) mature on space launch systems. development plan is based upon an • Two-stage-to-orbit: air breath- Application of these existing assessment of the current technology ing plus rocket (TSTO A/R). readiness levels (TRL's) for major techniques to launch vehicles permits real-time identification systems and subsystems of advanced After reviewing each configuration, technology vehicles. The class of it was evident that there were several of vehicle subsystem status. Definition of critical items to be launch vehicles represented has the core technology areas that were monitored and stored, develop- potential for major reductions in essential for the development of ment of data transfer techniques, annual space launch vehicle operat- all the concepts. These common "smart" management algorithms, ing costs. Single-stage-to-orbit and enabling technologies include the and development of ground two-stage-to-orbit systems have been following: assessed in this process to ensure processing procedures are included in this task. maximum flexibility for implementa- • Reusable Cryogenic Tanks: tion when these technologies have A common element of fully reus- been brought to maturity. able vehicles that has not been Autonomous Flight Control: explored in prior technology To achieve low-cost space trans- Tasks are presented that bring the efforts is the development of portation, most in-flight func- most promising technologies to a long-life/low-maintenance reus- tions must be automated and TRL 6 (system or subsystem model able cryogenic tank systems. The control responsibility transferred demonstration in a relevant environ- cryogenic tank system includes to the vehicle. Autonomous ment). A major consideration in the both the tank structure and insu- flight control is both possible development of these tasks is low lation. Included in this task is: and near state of the art for operational costs. Each vehicle con- the development of tank certifi- ascent, reentry, and landing, cept being defined by the Advanced cation criteria; nondestructive On-orbit operations, such as Technology Team stresses low op- evaluation (NDE) techniques; routine rendezvous and docking erational costs, and the technology establishment of a materials data at the space station, are also tasks have been developed with this base; optimization of materials near state of the art and are

14 Advanced Studies

under development by NASA. Advanced Technology Team. These technology requirements include This task objective is to develop technologies are also considered to advanced material studies and stud- and demonstrate these integrated be high-priori W requirements for ies relating to the production and techniques. each configuration. It is possible to transfer of slush hydrogen (He). develop the specific technology tasks Some technology development is Operations Enhancement associated with these enabling tech- required for the linear aerospike Technologies: The focus on low nologies without having to select a rocket engine system. operations cost approaches for given configuration or concept for space launch systems has re- development. The TSTO A/R combination concept sulted in an assessment of opera- requires technology development of tions requirements derived from In addition to the core technologies the turbojetramjet air-breathing a series of studies and bench- discussed above, some enabling propulsion system and an expander- mark eva]uations. Several key technologies are unique for the spe- cycle lox/LH, rocket engine system. areas requiring further investiga- cific configurations being considered, Additional materials technology is tion include operable and reli- For the SSTO R concept, the key required for titanium matrix compos- able rocket engines, leak-free technology requirement is for the ite materials used fi_r control surfaces. mechanical joints, and electro- development of a long-life, low- mechanical actuators/electrohy- maintenance, advanced liquid oxy- Sponsor: Office of Space Systems draulic actuators. gen/liquid hydrogen (lox/LH 2) Development engine derived from the space Long-LifeLow-Maintenance shuttle main engine (SSME). An alter- Thermal Protection System nate approach would be the devel- (TPS): The development of a opment of appropriate technology long-life/low-maintenance TPS is for a tripropellant engine system required to decrease the opera- (Russian RDT01 design or equivilant). tional costs of reusable vehicles. Tasks to investigate toughened For the SSTO A,/R combination con- rigid ceramic insulation (TUFI), cept, several unique technology tailored advanced flexible blan- requirements exist. An extensive ket insulation (TABI), carbon- technology program is required for silica carbide hot structures, and the air-breathing propulsion system, direct-bond reusable surface including the development of several insulation are included in this flight experiments that will be used activity. to demonstrate and calibrate ramjet/ scramjet operations. In addition, this These core technology requirements configuration uses an actively cooled are shared by all three basic configu- TPS that will require an extensive rations being considered by the technology program. Additional

15 f

Research and Technology 1993 III I I Earth System Science

Numerical Modeling For other values of the heating and Recent work has placed emphasis on of Nonlinear Baroclinic rotation, the flow may be made of vacillatory flow in the baroclinic Fluid Systems steady, regular waves, or it may be annulus experiments. The flow oc- quite irregular and chaotic. Such curring in the gap between two con- experiments have been conducted in centric, co-rotating cylinders that are Timothy L. Miller/ES42 the laboratory, both at MSFC and differentially heated is computed 205-544-1641 elsewhere, and a numerical model with high resolution and, typically, developed at MSFC is being used to for several tens-of-rotational periods. In developing an understanding of test the ability to predict the type of For certain combinations of rotation the processes that affect global flow and to assist in the develop- rates and temperature differences, change of the planet Earth, a compo- ment of an understanding of such the resulting flow is 3-D and under- nent that offers one of the greatest processes as heat and momentum goes a periodic oscillation in the challenges is the fluid system com- transport. Studies are being per- amplitude of the "wave" part of the prised of the atmosphere and formed additionally to help design structure. Agreement between the oceans. Clearly, the objective of future space-flight experiments using compute r simulations and previous understanding this system is an im- the Geophysical Fluid Flow Cell laboratory experiments is very good. portant one since the atmosphere is apparatus described below. The computer calculations allow the the fluid system in which we live, investigation of more cases than which supplies the land with fresh The model has been developed for have been done experimentally. This water, and which shields life from the study of these flows (geophysical work has resulted in the demonstra- harmful solar radiation. Due to the fluid flow simulator (GEOSIM)), and tion that a numerical model can be complex nature of this system and is able to study either spherical or used to identify the boundaries of the difficulty in obtaining sufficient cylindrical flows. Analysis of the regions in parameter space that are observational data on it, accurately flows proceeds in several steps: deterministically predictable, as op- predicting or even understanding its calculation of the axisymmetric flow posed to regions in which the result behavior for all but very short time (that which would be seen if no is highly sensitive to numerical and periods remains an elusive goal. The variations in longitude are allowed); physical parameters. An investigation calculation of the linear stability of goal of the research efforts described into the mechanics of the various here is to develop a better under- that flow to three-dimensional (3-D) flow regimes is continuing. standing of the Earth system through wave perturbations; calculation of the use of computer models that the wave amplitude where interac- Miller, T.L.; Lu, H.I.; and Butler, K.A. allow the study of the complicated tion between the wave and the lon- gitudinal mean flow is allowed; and, 1992. A Fully Nonlinear, Mixed behavior of a rather simple fluid Spectral and Finite Difference Model system that is driven by horizontal finally, the calculation of the fully for Thermally-Driven, Rotating nonlinear flow with full interaction temperature gradients and influenced Flows. Journal of Computational by rotation. between all components of the flow. Physics 101:265-75. The extent to which each of these One of the means for studying the steps can be directly applied to the Lu, H.I.; Miller, T.L.; and Butler, K.A. behavior of the Earth's atmosphere actual flows depends upon the 1993. A Numerical Study of and oceans is to conduct laboratory nonlinearity of the flow, which in Wavenumber Selection in the experiments in cylindrical and turn depends upon the experimental Baroclinic Annulus Flow System. spherical containers where a fluid parameters. For highly nonlinear Submitted to Geophysical Astrophys- such as water is differentially heated flows, time series of images of the ics Fluid Dynamics. and rotated. Depending upon the predicted flow are produced, and strength of the differential heating these are shown in computer anima- Sponsor: Office of Mission to Planet and the rate of rotation, the flow tions to illustrate the interactions Earth may be very simple--steady in time between various types of structures and axisymmetric in structure. in the flow.

18 Research Programs

Diagnostics of the Global 9ON

Hydrologic Cycle 60N ERBE j_ REGiISCCP Franklin R. Robertson/ES42 30N REG1REG2N7 _._ 205-544-1655 -I EQ REG2ISCCP _¢_ The prominent role of water in all q three phases of the global hydro- 30S logic cycle distinguishes Earth's physical climate system from those 60S of its planetary neighbors in the solar 90S I I system. Moisture transport and phase -120 -100 -80 -60 -40 -20 0 20 40 60 changes constitute the essential link RmliotiveFlux (Win-2) in converting incident solar radiation to kinetic energy of the atmosphere- FIcure 1 1.--Latitudinal distribution of zonal average net CRF ocean system. The thrust of this obtained from three methodologies (ERBE, REG1, research program is to understand and REG2) and two cloud data sets (N7 and ISCCP). how the cycling of water, particularly within the Earth's atmosphere, helps for vapor, liquid, and ice. These determine the character of climate ranged from about 2 to 27 Wm 2. Using three different methods of equations, which also use bulk on different time and space scales. computing CRF from satellite solar parameterizations of cloud micro- Near-term research centers upon and long-wave estimates, each em- physics (e.g., condensation, auto- understanding the role of hydrologic ploying data from February and conversion, collection, precipitation process in governing reservoirs of March 1985, an estimate of approxi- evaporation, and fallout) are up- water on Earth (i.e., the mass cycling mately 17 Wm -2 net cooling was dated, or constrained in such a way of water), and upon understanding found. Furthermore, the largest dis- that where SSM/I observations are the radiative implications of clouds agreement between methods being available in space and time, the and water vapor on climate variabil- 3.5 Wm -2, we were able to demon- evolving model vapor is "nudged" ity. This approach carries an empha- strate that earlier disagreements were to those values. sis on merging remotely sensed primarily due to use of different data data from space with conventional sets and analysis times. The moisture fields reconstructed gridded analyses of atmospheric state from this methodology have been variables (e.g., wind, temperature, From a water mass cycling standpoint, compared to available cloud clima- and humidity} available from opera- we have continued to investigate tologies such as the International tional numerical weather and climate combining colunm-integrated atmos- Satellite Cloud Climatology Project prediction centers. pheric water vapor from the space- (ISCCP). Such comparisons allow borne Special Sensor Microwave scientists to understand how cloud One research effort examined the Imager (SSM/I) with kinematic con- fields and water vapor distributions straints from global gridded analyses effects of clouds on global and zon- are governed by large-scale transport ally averaged temperatures. Low" (e.g., those produced by the European processes and ensemble convective Center for Medium Range Weather clouds tend to reflect more solar processes (fig. 11). radiation than they trap terrestrial or Forecasts (ECMWF)) as a means of long-wave radiation. This yields a reconstituting vapor, cloud, and Sohn, B.J., and Robertson, F.R. 1993. net cooling effect on the Earth sys- precipitation in three dimensions lntercomparison of CRF: A Zonal tem. Conversely, high clouds tend and in time. This basic formalism is and Global Perspective. Bulletin _f to trap more terrestrial radiation what isPtermed a semiprognostic the America n Meteo rolog ical Societl' 74:997-1006. than they reflect incident solar radia- assimilation procedure, since only tion. Earlier estimates suggested that the evolution of the moisture fields is Sponsor: Office of Mission to Planet the net effect of clouds, known as being predicted. Horizontal wind Earth cloud radiative forcing (CRF), was to fields and vertical motions from slightly cool the Earth's system. How- ECMWF gridded analyses have been ever, the amount of estimated cooling used to drive conservation equatkms 19 Research and Technology 1993

Mesoscale Modeling Coast of the United States during intensification through subsequent Related to the winter months. The influence of air- latent heat release associated with Hydrologic Cycle sea interaction processes associated precipitation processes. with sea-surface temperature patterns on these systems is currently being Another LAMPS-related project William M. Lapenta/ES42 investigated. Differential heating and involves the impact of sampling 205-544-1667 moistening of the lower atmosphere frequency on heat and moisture across the north wall of the Gulf diagnostics. For many years, diag- The need to better understand the Stream is thought to force mesoscale nostic studies of heat and moisture hydrologic cycle and the moist pro- baroclinic circulations in the marine budgets for large-scale circulations cesses affecting that cycle, before the atmospheric boundary layer that have been studied by evaluating the impact of observed Earth system provides an energy source for the difference between the large-scale changes such as increased carbon explosively deepening cyclone. heat and moisture tendencies and dioxide (CO_,) can be accurately However, the above hypothesis is their associated advective fluxes predicted, is well documented. As a based primarily on statistical data calculated from the circulation and result, several scientists at NASA and has not yet been confirmed thermodynamic fields. In preparation have been using a mesoscale model- through other scientific research for the CGIP, this project has focused ing system, the Limited Area Meso- techniques. Therefore, a series of on the impact of spatial and tempo- scale Prediction System (LAMPS), to sensitivity experiments using four- ral sampling frequency on the diag- aid in understanding more about the dimensional (4-D) data assimilation nostic heat and moisture budgets for hydrologic cycle. With the impor- has been conducted over the past several convectively active systems tance of global change and as the 2 yr using LAMPS to test this hypo- over the midwestem United States. observing phase of the Global En- thesis. Significant findings include: Mesoscale model simulations have ergy and Water Cycle Experiment (1) that a 4-D data assimilation can been used to test the impact of "ob- (GEWEX) Continental International be successfully employed within a servation resolution" on the accuracy Project (GCIP) approaches, it is par- sensitivity test framework to investi- of the diagnostics. The observation ticularly appropriate that the hydro- gate air-sea interaction processes, resolution is varied by sampling the logic cycle be investigated, with (2) the sea surface temperature gra- model simulations at various spatial special emphasis on the impact of dient associated with the Gulf and temporal intervals. Preliminary smaller atmospheric scales. Below is Stream's north wall forces a region results to date include the following: a brief description of several ongoing of enhanced baroclinity within the (1) both heat and moisture budgets projects at MSFC that employ LAMPS atmospheric marine boundary layer vary as spatial and temporal sam- to better understand moist atmos- through differential heat and mois- piing is changed, and (2) individual pheric processes associated with the ture fluxes, (3) a negative correlation vertical profiles of heating and moist- hydrologic cycle. was found between the strength of ening indicate that at least one of the the low-level baroclinity and cyclone quantities significantly affected by It is well known that air-sea interac- intensity that directly opposes the horizontal sampling is the horizontal tions have a profound impact on hypothesis of many other investiga- advection term at midlevels. atmospheric circulations and, there- tors, (4) a positive correlation was fore, can affect the meridional atmos- found between cyclone intensity and Slmnsor: Office of Mission to Planet pheric transport of heat and moisture. reduced lower tropospheric stability, Earth Such circulations include rapidly and (5) increased evaporative fluxes intensifying cyclones off the East had a positive impact on cyclone

2O Research Programs

Lightning Radiative phenomena, MSFC currently etnploys where D is the diffusion coefficient, Transfer Inversion complex radiative transfer modeling q_lmn is an eigenfunction with corm- Studies techniques. A Boltzmann transport sponding eigenvalue, ,a.lmn, Vis the model with diffusion approxima- volume of the cloud, and the vari- tions, commonly applied to the ables (r, .O, t) are the fundamental William J. Koshak/ES43 problem of nuclear reactor analyses, location, direction, and time vari- 205-544-8749 has been developed to track source ables, respectively, in the transfer photons throughout the thunder- problem. The eigenfunction and Measurements of cloud-top lightning cloud medium. Using this forward eigenvalue depend on the geomet W optical waveforms have been col- radiative transfer model, ck)ud-top of the cloud, and the diffusion coefli- lected from high-altitude U-2 aircraft waveforms have been generated that cient depends on the cloud scatter- flights above thunderstorms. A study closely resemble actual U-2 optical ing properties. In etl_+ct, the kernel of the diffuse, cloud-top lightning pulse sensor (OPS) data sets. matrix contains all that is needed illuminations may provide some (given model assumptions) to relate knowledge about the embedded To obtain useful infomlation about measured optical signals to source lightning source emissk)n (including the properties of the lightning emissions. A formal inversion of the the source brightness, rise-time char- source, the inverse transfer problem kernel matrix provides a solution fl)r acteristics, pulse width, and source has been investigated. A theoretical the source location and brightness. location and geometry). Measure- study of this transfer problem has ments of the cloud-top optical wave- revealed that the source strength,f, Sponsor: Office of Mission to Planet forms may also provide some useful (in units of intensity: W/m'/sr) is Earth knowledge about the microphysical related to a set of intensity measure- state of the thundercloud within ments, g, via a linear matrix equation: which the lightning source is em-

bedded (e.g., properties such as the g =Af+e ( 1) number distribution of cloud particle where _ is a column vector of mea- scatterers, the cloud particle com- surement errors and kernel trunca- position, orientation, and spatial tion errors. The elements of the distribution). In addition, these meas- kernel matrix, A, are given by: urements might be useful in retriev- ing the bulk electromagnetic proper- ties of the cloud such as the bulk A ,-+ZEZ permittivity, & and permeability, It. /=1 m=l _*=1 Because thunderclouds are finite, O,-++,,+,,(r,,] three-dimensional, and multiple- scattering media, and because a q)t,,,, (_) e-_4"'( "- t,J lightning discharge is a spatially tortuous and a highly transient

21 Research and Technology 1993

Defense Meteorological Satellite Program Optical Linescan System Data System Global Survey of Lightning

Steven J. Goodman/ES42 205-544-1683

This project is an effort to develop a climatology of lightning activity from the nighttime Defense Meteorlogical Satellite Program (DMSP) Optical Linescan System (OLS) images and to interrelate the lightning to the SSM/I brightness temperature and precipitation data base for the F8, F10, and Fll series. In addition, this research supports the design and development of a DMSP climate FIGURE12.iFlag DMSP F80LS lightning August 1987 archive data base at the National (ASC/DESC 0635/I 835 UTC). Snow and Ice Data Center. Though the archive data are not yet routinely available to the user community, the Air Force Global Weather Central has temperatures derived from SSM/I have suggested that the algorithm be been reliably copying DMSP data to antenna temperatures (TA's) using recalibrated with another indepen- 8-mm tapes and shipping them to both Wentz and Navy methodolo- dent data set, such as the AMEDAS the National Oceanic and Atmos- gies. No statistically significant differ- combined radar/rain gauge surface pheric Administration (NOAA) ences were found to exist, implying rainfall data base collected in Japan National Geophysical Data Center that the Cal/Val rainfall algorithm during the Algorithm Intercom- (NGDC) archives in Boulder, CO, estimate is the same whether Wentz parison Project 1 (AIP1) as part of since September 1992. or Navy SSM/I brightness tempera- the World Meteorological Organiza- tures (TB's) are used as the input tion (WMO) sponsored Global Pre- The F8 OLS lightning data were data to the algorithm (fig. 13). This digitized for comparison with global cipitation Climatology Project. This result permits us to compare precipi- rainfall estimates for the period can be accomplished using nonlin- August to November 1987. The F8 tation algorithms based on Wentz ear regression modeling of the ob- lightning map for August 1987 is TB's with the operational Cal/Val served brightness temperatures shown in figure 12. MSFC scientists' algorithm. The goal is to ultimately against the surface rainfall data set in participation in the WETNET Precipi- compare the thunderstorm activity a like manner that was performed in tation lntercomparison Project 1 (derived from the OLS lightning data the original development of the algo- (PIP1) consisted of submission of base) with the various algorithm rithm at the University of Wisconsin. estimates of rainfall. The value of this the Navy Cal/Val precipitation algo- rithm to serve as a baseline rainfall study to NASA's mission is to de- Initial intercomparisons show that velop improved global rainfall esti- estimate covering the same August the Cal/Val algorithm generally un- mates for the Mission to Planet Earth to November time period. derestimates monthly rainfall by a program. The practical benefit is that factor of two when compared with In order to ensure that the Cal/Val we believe we have discovered the other rainfall algorithms. It has been algorithm was implemented prop- major source of error in the current found that the chief source of error erly using the WETNET test data operational SSM/I rainfall algorithm from the Cal/Val rainfall algorithm set, we compared the brightness used by the U.S. armed forces. We is attributable to the "ground-truth"

22 Research Programs

300

290 10,000 ,,ooo_ il i 280 +,ooo_ II i ,,ooo_ In i 270 ',°°°1- II I _-"°°°r II I 260 ,ooo_ il i 250 ,,ooo_ II I _+ooo_ ,il i

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190

180

170

160

150

140 I I I I I I i i I I I I I I I 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 Wutz V85 grigktmssTemperotwe(K)

FIGURE13.--Scatterplot of Wentz versus Navy (Cal/Val) V85 brightness temperatures for August 16, 1987--rev 806 (ascending)--Iand/ocean data. data set used to calibrate the Goodman, SO.; LaFontaine, FJ.; Huffman, Sl_nsor: Office of Mission to Planet algorithm. The calibration data set G.J.; and Adler, R.A. June 1993. An Earth Intercomparison of the Navy Cal/Val apparently did not contain a repre- and SSM/I Pathfinder Precipitation Urtiv¢_ity Involvement: University sentative sample of high rain-rate Algorithms, Shared Processing Net- of Wisconsin events. Thus, the low rain-rate statis- work (SPN). Special Sensor Micro- tics cause the algorithm to be biased wave/Imager (SSM/I) Algorithm towards the lighter rain events. Symposium. Monterey, CA. 23 Research and Technology 1993

Global Aerosol lidar field campaigns in remote hierarchical data format (HDF) Backscatter Experiments locations, satellite-based aerosol archival. Detailed intercomparison measurements, and laboratory-based and quality control of the data sets calibrations of the various aerosol are being performed. Maurice A. Jarzembski/ES43 sensors. These include direct mea- 205 - 544- 0240 surements of aerosol scattering prop- Case studies for several GLOBE II erties at selected laser wavelengths Accurate remote sensing of tropo- flights have been accomplished for and information on aerosol physical, spheric wind profiles from a space- relationships among various aerosol chemical, and optical properties based lidar depends on adequate parameters. Intercomparisons are needed to model aerosol scattering aerosol backscatter availability. made with meteorological data from properties at other wavelengths Strength of the atmospheric back- where no direct measurements are European Center for Medium-Range scatter determines the signal-to-noise Weather Forecasting global gridded available. Also, some sensors provide ratio (SNR) of the return signal. The analyses and geostationary satellite information on aerosol properties in key to the lidar's performance is its data in an effort to establish the locations where no direct measure- sensitivity, the maximization of extent of correlation between aero- ments have been obtained. The most which requires use of an optimum sol backscatter and meteorological important measurement program was operating wavelength. Research variables. Of all the meteorological efforts at MSFC involve assessment the GLOBE backscatter flight survey missions over the Pacific Ocean in variables examined, relative and of global patterns of backscatter, specific humidity exhibit significant fall 1989 (GLOBE I) and spring 1990 including both theoretical and ex- correlation with aerosol backscatter. (GLOBE II). perimental studies of atmospheric Figure 14 shows time series of corre- aerosol scattering properties using lation between vertical profiles of data from NASA's Global Backscatter Diverse measurements from these measured aerosol backscatter mixing Experiment (GLOBE). field campaigns have been compiled ratio and large-scale gridded relative in a centralized GLOBE data base, de- humidity field from ECMWF data for The GLOBE program involves coop- signed and implemented at MSFC. GLOBE II flight 12. The correlation erative research efforts among uni- The data base uses a high-end UNIX studies indicate two principal modes versities, other NASA centers, other workstation, magneto-optical disk of statistical behavior, with high government agencies, and interna- mass storage, Ethernet connectivity correlation between backscatter and tional organizations, under the scien- to MSFC computing resources, Inter- relative humidity in maritime air tific direction of MSFC. Major net connectivity to other GLOBE masses, and lower correlation in jet experimental efforts include a net- researchers, advanced data visual- streams near and downstream from work of CO 2 lidar stations, intensive ization/analysis software, and large landmasses. Physical, chemical,

1.0

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FIGURE14.--Correlation of pulsed lidar measurements with relative humidity measurements.

24 Research Programs

10-7

104 i '°-'[ " vt eL:i_i'.'.a.'_-_::4 /

_10-9 E =- F _/" J'+'," ,,0

,0-,L- / I • toeco,. i, 10-10 • / I, ,o coata.. / I_ / / I--- PureModelI / I -- CompositeModel I

/J, .... t ...... I,I ° GSFC-JPLtUdarData' 10-]° .- 1- " -11 lO-]O 10-9 10-8 10-7 t0-6 10 1(i--I1 10--]0 10--9 10--8 10--1

!.06 pm gackscatler 9.1 _m Backscatter LOPCLoserOpticalParticleCounler GSFC:GoddardSpaceFlightCenter JPL:JetPropulsionLaboratory

FIGURE1&--Comparison of pulsed lidar data, microphysics data, and modeled aerosol backscatter.

International Laser Radar Confer- and optical properties are modeled backscatter for various aerosol com- ence. Massachusetts Institute of for major aerosol types and used to positions provide an envelope for Technology, Cambridge, MA. estimate typical ranges of aerosol the variations in measured data; backscatter values for each aerosol however, composite aerosol models Cutten, D.R.; McCaul. E.W., Jr.; of a mixture of the various composi- Wpe and compared with direct aero- Spinhirne, J.D.; Menzies, R.T.; sol backscatter measurements. An tions lead to an average backscatter Pueschel, R.; Clarke, A.I).; and example is shown in figure 15 as that is in good agreement with mea- Bowdle, D.A. 1993. Comparison of cross-plots of aerosol backscatter surements. Such intercomparisons Remotely Measured Multispectral coefficients at selected pairs of laser between various measurements and Scattering Parameters for Tropo- wavelengths. Pulsed lidar measure- modeling provide empirical conver- spheric Aerosols. Technical Digest ment values (dots) from flight 12 sion factors to enable estimation of _:403_o. Topical Meeting on Optical were obtained between 6.5 and aerosol backscatter at any required Remote Sensing of the Atmosphere. Optical Society of America, 7.5 km altitude. Backscatter calcula- wavelength from direct measure- Washington, I)C. tions from aerosol microphysical ments of aerosol backscatter made at measurements obtained from Univer- only specific wavelengths. Results McCaul, E.W., Jr.; Bowdle, D.A.; sity of Hawaii Laser Optical Counter are being combined in a preliminary Cutten, D.R.; Menzies, R.T.; and (triangles) compare very well with global-scale empirical model of aero- Spinhirne,.I.D. 1993. Relatic)nships lidar data at various wavelengths. sol backscatter properties at a pro- Between Lidar Backscatter and Modeled values (curves) were com- spective space-based lidar Meteorological Fields. Techuical puted from Mie scattering for typical wavelengths. Digest 5:407-10. Topical Meeting atmospheric aerosol compositions (m Optical Remote Sensing of the (sulfuric acid, ammonium sulfate, Atmosphere. Optical Society of Bowdle, D.A. 1992. Global Backscatter America, Washington, I)C. and dust), using log normal distribu- Experiment (GLOBE) Results: Aero- tions with constant mass concentra- sol Backscatter Wavelength Depen- Sponsor: Office of Mission to Planet tion of 1.0 lag m -_and geometric dence and Global Distribution. Earth mean particle sizes from 0.91 pm A'ational Aeronautics and Space (left terminus of curves) to 19 lam Admiuistration Co_rfi,rence Publica- (right terminus of curves). Modeled tions 3158, part 1:57-60. Sixteenth

25 Research and Technology 1993

Global Atmospheric increase of temperature from global be compared with the observations, Modeling warming should increase the atmos- so that the effects of realistic SST pheric moisture because the air can forcing can be separated from the hold more water vapor. The ampli- intrinsic chaotic variations of the Daniel E. Fitzjarrald/ES42 205-544-1651 tude of the mid-latitude eddies may model climate when the SST forcing therefore increase because of added is the same from year to year. The latent heat release in the storms, or analysis techniques of these data There are many pitfalls on the path the amplitude may decrease because include comparing the variances and to producing a predictive capability for the climate. Numerical models of increased latent heat transport in computation of principal compo- the warmer air. The final result may nents of variation. The position and offer the best hope for a theoretical be a combination of these effects, strength of persistent features such description of climate dynamics that with the increase at smaller scales as storm tracks, monsoons, and the could lead to prediction, since they and the decrease at larger scales. If Intertropical Convergence Zone can capture the essential non- the relevant parameterizations and (ITCZ) will also be useful in validat- linearities and the myriad of compli- cations. But model calibration and model resolution are not adequate, ing the model performance and the wrong conclusion may be drawn identifying areas for improvement in validation, crucial steps in develop- from model simulations. moisture parameterizations. ing any believable theory, remain elusive. It is not enough to validate Model resolution will also be varied, against the present climate to draw Scientists at MSFC are using global within limits, to find a happy me- a portrait of the subject, so to speak. atmospheric data to evaluate the dium between improvement of the Because the subject will not stand performance of the Genesis global simulation and manageability of data. still, it is necessary to get all the parts atmospheric model, which was de- Our experience, and that of others, right and bring the subject to life. veloped at the National Center for Atmospheric Research. We are con- using the prior generation of global The real use of predictive capability climate model was such that increas- will not likely be a sort of next-gen- centrating on the moisture variables; ing the model resolution does not eration climate forecast (who would i.e., precipitable water, rainfall, cloud amount and type, etc. The annual always improve the simulations, that be in charge of validation, anyway, is, make the results look more like this generation or the next?), but and interannual variations in the the real atmosphere. It has been rather will be used in conducting observed data provide a good testing speculated that these inadequacies sensitivity studies and scenarios for ground, allowing the response of the different courses of action or for model to be evaluated and com- were due to the cumulus parameter- ization, the surface hydrology mitigation. All the parts of the simu- pared with the present climate. Ap- model, or the tuning of other para- lation must be right in order that the proximately a decade is available for meterizations. The surface hydrol- dependence on all the variables can comparison and analysis, including ogy, cumulus parameterization, and be correct, for it is not known ahead 13 yr of the Microwave Sounding other parameterizations have been of time which ones will be changed. Unit (MSU) data (tropospheric and stratospheric temperature and rainfall improved in the Genesis model. So, In looking at global warming, for over water). We have made a run of leaving aside some amount of tuning example, in response to increased 10 yr at low resolution (15 waves that may be necessary, it is expected CO 2 or other radiatively active gases, resolved around the globe) using that the Genesis simulation will do there are many aspects of the atmos- observed sea surface temperatures better at higher resolution. We plan phere and ocean system that may (SST) and have compared them with to make at least part of a decade- change. Many of these changes that MSU-derived temperature and rain- long run with prescribed SST's, along are of critical interest involve water fall. Also available for use are two with a climatological control, at substance. Both in estimating the control runs of 10 yr at the same higher resolution (42 waves around local effects of a given climate resolution, one with the simple the globe). change (droughts, etc.) and in pre- quasi-swamp ocean model and an- Sponsor:. Office of Mission to Planet dicting the climate change itself, other with prescribed climatological Earth moisture and its transport are indis- SST. The latter control run allows the pensable quantities. For example, an intrinsic variations of the model to

26 Research Programs

Spatial/Temporal u component, and 1.55 m/s for the the overall mean was 5.8 m/s; stan- dard deviation, 3.76 m/s; and root Variability of Wind Fields v component, and a standard devia- tion of 2.27 m/s for the vector wind. mean square, 4.43 m/s. for Design of Remote Sensors The existing technology for the past The following data analysis of the three decades (1960's, 1970's, and comparison of the wind components Michael Susko/ES43 1980's) and the present decade measured by the FPS-16 Radar/ 205-544-1660 (1990's) in measuring winds for the Jimsphere Balloon System and space shuttle launches, has been NASA's 50-MHz Radar Wind Profiler The primary objective of this research obtained by the balloon-borne provides an excellent quality check project is to report on the spatial and FPS-16 Radar/Jimsphere system. of the winds provided by the GOES-7 temporal variability of atmospheric NASA's 50-MHz radar now plays an satellite. flow fields in the troposphere and important role in monitoring winds lower stratosphere for developing for substantial profile changes during A comparison of the u- and v-wind design criteria information for remote the day of launch. These compara- components for the Jimsphere bal- sensors of satellites. The analysis of tive data sets were evaluated and loon and the Radar Wind Profiler is the bivariate parameter wind speed their spatial and temporal variability presented in figures 16 and 17 for differences between the FPS-16 were reported (Susko 1993). The STS-43 (Space Shuttle Atlantis). The Radar/Jimsphere Wind System and successful interpretation of satellite Radar Wind Profiler wind data are NASA's 50-MHz Radar Wind Profiler data depends on a reliable and computed for a length scale every will reduce the uncertainties in per- proven wind sensor. 150 m, and averaged over 30 m, formance studies of satellites and while the Jimsphere is computed for enhance the validation of the atmos- From NOAA's National Environmental 30 m. Thus the Jimsphere/Profiler pheric and satellite performance Satellite Data and Information Ser- Wind Profile data sets are plotted studies. This study provides a quality vice (NESDIS) and from the Univer- and compared every 30 m. Figures 16 check for satellite winds. Compari- sity of Wisconsin's Office of Research and 17 illustrate the u and v compo- son of the flow fields in the tropo- and Applications Laboratories, satel- nents comparison of winds aloft sphere and lower stratosphere of lite winds obtained by the Geosta- during the STS-43 launch. Six case studies of pairs of Jimsphere tionary Operational Environmental Jimsphere/Profiler wind data sets balloon releases and Radar Wind Satellite (GOES) were assessed. The were compared at 0902Z, 1047Z, Profiler winds during space shuttle GOES satellite operational wind 1202Z, 1302Z, and 1517Z. The stan- launches was performed. The statis- measurements from the cloud dard deviation for u-wind compo- tics of the mean and standard devia- motions during the space shuttle nent differences was 1.39 m/s and tion of the zonal component (u) and launches at KSC, FL, of STS-37 and 1.45 m/s for the v-wind component. meridional component (v) and STS-43 on April 5 and August 2, 1991, The overall standard deviation for power spectra density curves show respectively, have been compared both launches was 1.66 m/s for the good agreement between the two with the FPS-16 Radar/Jimsphere vector wind. These data sets provide wind sensors. The standard devia- Balloon Systems wind measurements. excellent truth verification during tion of the u and v components The statistical results for STS-37 assessment of the GOES-7 satellite for shuttle mission STS-37 (five launch winds comparison were as data. Jimsphere/profiler wind profile data follow: mean, 5.69 m/s; standard sets) was 1.92 nVs and 1.67 m/s, deviation, 4.37 m/s; and root mean The results of satellite wind assess- while for the STS-43 launch (six square, 4.45 m/s. The results for the ments using the visible infrared spin- Jimsphere/profiler wind profile data STS-43 launch wind comparison scan radiometer atmospheric sounder sets) was 1.39 m/s and 1.44 m/s, were: mean 5.91 m/s; standard de- (VAS) data to assign simultaneous respectively. The overall standard viation, 3.15 m/s; and root mean heights and velocities of cloud deviation was 1.66 m/s for the square, 4.41 m/s. For both launches, motion winds CO, cloud tracking

27 Research and Technology 1993

10

• SymbolsTime

-10 • 1511

,o0F"_'10 ..... i -ioI- __. -,__ _-..d_.-_-,.._,,,_ -_. __ -,0 ,0- \ . .-

-2o-o_ -_ _..,_ -lo ',, •

-20_ _ I _ I I I " I I " I 0 2 4 6 8 10 12 14 16 18 210 Altitude(kin)

FIGURE1&--Six u-wind components of the NASA 50-MHz Radar Wind Profiler overlayed on the wind profile of the FPS-16 Radar/Jimsphere measured during the STS-43 launch, August 2, 1991, at KSC, FL. technique that combines the CO 2 If a sequence of cloud images from a lifetime of the clouds being traced. slicing and absorption methods is geostationary satellite (GOES-7) In order to get a greater density of presented. Tracking clouds at high, move with the wind, it is possible to cloud motion vectors close to the middle, and low levels can be accom- describe the motions of the atmos- KSC station, they were selected plished by utilizing time sequences phere. Figures 16 and 17, with sym- manually. This was done by choos- of C% channel images as indicated bols x and o, indicate GOES-7 ing a target and following it by eye by Menzel et al. This CO z slicing satellite wind data overlayed on the and letting the computer do the method improvescloud motion vec- Jimsphere/Radar Wind Profiler data. vectoring and pressure. This is the tor (CMV) winds determination. procedure used in assessing the Methods used to derive the "cloud CMV. The average distance of wind High resolution of wind measure- drift" require using good geostation- measurement between the GOES-7 ments from satellite imagery provides ary satellite images of fine geometric satellite winds and Jimsphere winds atmospheric motion through mea- fidelity, with time intervals between was 65 km. The global comparison surement of cloud displacement. image of approximately 30 min, the of satellite/Jimsphere balloon vector

28 Research Programs

10 _ _ SymbolsTime ._t ,,Lj_, - -__ 1517Z .x_,.,- _ _,, -4 _ L_.. z 10 1517 -10

"e • ed "" • ,..._ z 1352 -20 o. Z "

""_o "_ .,% ._,,_% -.,_j ...,

i -20 0 -0 _ - - -f "4. -..'W "il_" "" • 1302

-20 10 "/___ _02Z _' "_." _ X 1202 -10 F f / "._. X.zxx _b,, _ 'T ot 2o;-/ ._ x'_'._ _ .^....._.

-_o-,o,k "'°4,z,o__,,, ....____._.'_ -_ ;. __._,h" ;,_ ../...• 1047 2L _ "_ _'_ -,:'_ - 0 0t- _ _ _ "_ ".. X 0902

-,o[ _,,_.¢,,, _" I I I i I I I I I I J -200 2 4 6 8 10 12 14 16 18 20 Ahit_le (kiN)

FK_URE17.--Six v-wind components of the NASA 50-MHz Radar Wind Profiler overlayed on the wind profile of the FPS-16 Radar/Jimsphere measured during the STS-43 launch, August 2, 1991,at KSC, FL. winds shows a standard deviation of lIerman, L.D. September 17-19, 1991. Susko, M. January 1993. Comparison of 3.15 m/s for STS-43 and 4.37 m/s The Current Stage of Development FPS-16 Radar/Jimsphere and NASA's of a Method of Producing Cloud S0 MHz Radar Wind Profiler. Ameri- for STS-37. The overall standard Motion Vector at High Latitudes can Institute of Aeronautics and deviation of the vector wind was From NOAA Satellites. Proceedings Astronautics (A1AA) paper 93-0758. 3.76 m/s and a root mean square of EUM P 10, ISBN 92-9110--0072:21- 4.43 m/s. It is demonstrated that this 26. Washington, DC. Sponsor: Office of Space Flight and unique comparison of the Jimsphere Applications Menzel, W.P.; Smith, W.L.; and Stewart, and satellite winds provides excellent T.R. March 1983. Improved Cloud University Involvement: [_niversity ground truth and a frame of refer- Motion Wind Vector and Altitude of Wisconsin ence during testing and validation of Using VAS..lou rnal of Climate and satellite data. Applied MeteoroloR}' 22:377-84.

29 Research and Technology 1993

Earth Observing System projection"). The antenna tempera- missing, mislocated, or out-of-bound Pathfinder Passive ture (Ta) data set includes spacecraft data--will be corrected or flagged Microwave Data Set and timing information, latitudes and by the MSFC Pathfinder processing. longitudes, calibration data, and Production The resulting data sets will satisfy the surface-type indices. The derived main goal of the Pathfinder project. geophysical products have not been H. Michael Goodman/ES44 fully defined but may include the SSM/I output data are stored in the 205-544-8006 following global parameters: ocean hierarchical data format. HDF is a surface wind speed, columnar liquid multiobject file format for the trans- The Earth Observing System Path- water content of clouds, columnar fer of graphical and floating-point finder will provide access to large water vapor, rain rate, land surface data between machines. It was de- remote-sensing data sets applicable temperature, land surface type, mi- veloped by the National Center for to global climate change research crowave vegetation indices, and sea Supercomputing Applications ice classification. prior to the availability of data from (NCSA). The HDF is the standard the EOS satellites. The main goal of data format for data distribution in the Pathfinder program is to make The SSM/I Pathfinder project is the Version Zero EOSDIS. research-quality, long-term global divided into two stages: benchmark change data sets easily available to and post-benchmark. The bench- the Earth science community. The mark period extends from August After quality control, the Pathfinder data sets currently selected are the 1987 to November 1988, and uses data will be archived on the MSFC GOES, the Advanced Very High only data from the DMSP satellite F8 Version Zero EOSDIS Distributed Resolution Radiometer (AVHRR), (launched June 19, 1987). The post- Active Archive Center (DAAC) opti- Television Infrared Operations Satel- benchmark period extends from cal disk storage device. The products lite (TIROS) Operational Vertical December 1988 to July 1994, when are concurrently listed in the direc- Sounder (TOVS), the Scanning Multi- the Version Zero Earth Observing tory for access through the EOSDIS channel Microwave Radiometer System Data and Information System Information Management System. (SMMR), and the Special Sensor (EOSDIS) becomes operational Distribution of the antenna tempera- Microwave/Imager. The EOS Path- (see MSFC Research and Technol- tures and the geophysical products is finder project emphasizes the coinci- ogy Operating Report 1992). The in discrete granules (e.g., 1-mo peri- dence of multisatellite observations post-benchmark period includes ods) on 8-mm tape. The benchmark for global change research. A signifi- data from DMSP satellites F8, F10 period SSM/I Pathfinder data will be cant portion of the MSFC Pathfinder (launched December 1, 1990), and available to the science community project involves the processing of F11 (launched November 28, 1991). through the MSFC DAAC by the end SSM/I data from the Defense Meteor- of 1993. ological Satellite Program F8 satellite. The satellite sensor data for the benchmark period were prepro- Sponsor: Office of Mission to Planet The MSFC component of the Path- cessed by Dr. Frank Wentz of Re- Earth finder project is focused on genera- mote Sensing Systems. Dr. Wentz ting passive microwave antenna performed extensive quality control. Commercial Involvement: temperatures and geophysical prod- The errors he identified---including Hughes/STX ucts in the satellite projection (com- geolocation and instrument calibra- monly referred to as a "swath tion errors, plus others, such as

3O Research Programs

Four-Dimensional In order to support this paradigm, an values of the physical parameters at Interactive Analysis ability to render semitransparent that location in time and space. Also graphics was necessary. For ex- provided is an ability for the scien- Capability ample, consider the outside of a tists to dynamically incorporate their thunderstorm and some intense rain own analysis function in the soft- Paul J. Meyer/ES44 shaft within the storm. Each may be ware. This allows for the derivation 205-544-1654 measured by a cloud liquid water of variables from the current base parameter; the outer cloud shell has parameters. This software currently For the past 7 yr, an interactive capa- a relatively low value and the rain runs on Silicon Graphics, IBM bility to analyze four-dimensional shaft has a high value. This low RS6000, and Stardent GS series com- (4-D) Earth science data sets has value would be rendered in some puters. Support for Sun computers is been under development. Develop- specified, user-controlled color as a being explored. It is publicly avail- ment of this tool was performed at semitransparent object, while inside able via anonymous file transfer the Space Science and Engineering the rain shaft would be rendered in protocol (ftp) from: Center at the University of Wiscon- a complementary color as opaque. vis5d.ssec.wisc.edu. sin-Madison. This effort is nearly Essentially, one sees inside the storm. MSFC personnel have added support complete, and the final product is to ingest the HDF from the National called Vis5D. The five dimensions The ability to interactively slice the Center for Supercomputing the tool handles are the three spatial 3-D volume with a color-mapped Applications. dimensions, time, and parameters. planar surface has greatly improved While developed for Earth science understanding as well. This may be Sponsor: Office of Mission to Planet data sets, the tool has been used for done in concert with the isosurfaced Earth other five-dimensional (5-D) data rendering. The user may animate this sets, including medical imaging. slice in time, and/or may grip the University Involvement: University Capabilities of the tool include slice and concurrently change the of Wisconsin-Madison isosurface rendering, topography, slice orientation. The slices may also streamlines, interactive 2-D slicing, be degenerated to simple contour and user-defined analysis. plots in 2-D space.

One of the strengths of the tool is The latest release of Vis5D provides the ability to render multiple iso- an ability to place a 3-D probe into surfaces of the same parameter. the data volume and determine the

31 Research and Technology 1993

Evaluation of solar activity where the models show in predicting day-to-day density Thermosphere Density a diverging trend. Evaluating the variations. However, due to the Models models at high solar activity is im- sparseness of the LDEF density data portant because of their use in the set, short-term variations on the aerospace community for predicting order of a day or less were not able RonnieJ. Suggs/ES44 satellite decay lifetimes, including to be analyzed. 205-544-7797 the space station reboost and ren- dezvous strategies during assembly, Thermosphere model systematic Spacecraft designing and mission which are planned to occur during errors associated with long-term planning depend heavily on a know- the rise of the next solar cycle. Fur- thermosphere variations often show ledge of the space environment. One ther motivation is provided by the up in applications as a model bias aspect of the space environment fact that some solar scientists predict error when working with time peri- continuing to be investigated is the that the next solar cycle may be one ods of 100 d or less. For longer peri- modeling of the upper atmospheric of the largest ever recorded (Wilson ods, these errors are seen as density at orbital altitudes. This re- 1992). time-varying bias errors that greatly gion of the atmosphere, called the affect orbital decay calculations. thermosphere, has been investigated During this past year, analysis was Analysts often correct for these bias over the years through many NASA completed comparing four major errors in satellite decay work by programs, resulting in the develop- thermosphere models, three of adjusting the drag coefficient of the ment of several thermosphere mod- which are the Jacchia models J70, spacecraft in their models to agree els currently used in the engineering J71, J77, and the fourth, the MSIS86 with current tracking measurements. community. It is the purpose of model. The J70 model, with the Analysts, in general, are aware that current investigations at MSFC to addition of two modifications from thermosphere model errors exist, evaluate several of the major thermo- the J71 model, makes up the but they are usually not familiar with sphere models against recent satellite Marshall Engineering Thermosphere the physical phenomena responsible decay-derived density data. (MET) model that has been selected for the errors or the degree of bias as the baseline model for the space variability to expect from the thermo- The motivation for the investigations station program. The MET model is sphere models. The LDEF analysis was the availability of recent satellite also contained in the thermosphere was an attempt to quantify the sys- decay data from a good candidate portion of the Global Reference tematic errors present in the models satellite during a time of high solar Atmosphere Model 1990 (GRAM-90). and determine the phenomena activity, as measured by the 10.7-cm The MSIS86 model forms the thermo- responsible for the errors. radio solar flux. Also, the solar activ- sphere portion of the most recent ity level associated with these data reference atmosphere, CIRA86. An important result found from the was such that it approached values analysis was determining the time- contained in the data bases used in The models were compared to the varying bias error associated with the formulating the models. Thermo- densities derived from the decay of variation in density with the solar spheric density data obtained from the Long Duration Exposure Facility cycle. A comparison of the LDEF satellite decay are currently the only satellite for the rise and peak of the density data with the thermosphere source of recent density measure- current solar cycle (cycle 22). The model calculations (fig. 18) shows ments available at orbital altitudes density data, which were average that the Jacchia models do well at and, thus, provide the only means to orbital values over periods of I to 4 d, modeling this variation for smoothed evaluate the performance of thermo- were used to determine how well 10.7-cm solar flux values greater than sphere models and to identify sys- the models predicted the known 110. On the other hand, the MSIS86 tematic errors that may be present long-term thermosphere variations model shows a diverging trend for during the rise of the current solar that are longer than a solar rotation this solar cycle region culminating to cycle. It is known that the models (27 d). Though the focus was on about a 10 percent over prediction in show disagreement among them- long-term variations such as solar density at the peak of the current selves as to the effect of the solar cycle effects and the semiannual solar cycle. For higher values of solar cycle variation on the thermospheric variation, some information was flux that might be expected for very, density, especially at high values of obtained on the models' performance large solar cycles, the trends suggest

32 Research Programs

2.0 possible bias errors on the order J...... Ratio II MSIS/LDEF of 20 percent. However, for solar flux values typical at solar minimum, .2 1.5 --loo-o M,o° I the MSIS86 and J77 models appear to compare well, while the J70 and 1.0 •.:_ii; .F-'- _,:..,.'.I:" "_'.., . _ _"_,1",__:."_ :. _i-;_ IJ !i'._ '._..: _ ":'_':"_i " :L_.!i'_l_"_'._l _.:; '_ ' J71 models perform poorly by over- ii ' 'i r predicting the density on the order of 20-30 percent. The J77 model 0.5 f:l I I I : I" I I l 2.0 seems to do better overall in model- J70/LDEF ing the solar cycle variation in ; ,. i o density. 1.5 IJ -i .."..i .:.... t i i .i nt, '._::.:,.'_'._..".".._..._ _ ..'..._'.'_.'.i,,;_,:,'...:.';i_l_ °_ Even though the mean errors pre- 1.0 sented in these results appear small, it is the combined errors associated i I ' ' : 0.5 with the different phenomena that 2.01 results in significant bias errors. J77/LDEF Moreover, relatively small bias errors on the order of 10 percent in the 1.5 Ill models applied over long periods , : : L: i .! . -: " : • :". _ i:'. _:':_ :': i:" : ". :'_"'J of time translate into large errors in 1.0 orbit-decay analysis. Also, since the •.':._-' '.". • "...._"-. ,,'_,,_r_...:_: ::_ .,_ : _: _,,. r_ ._ ", mean error is not simply an offset _; • . ._._ , , ! ' bias, but varies with time, it becomes 0.5 i I I I :I' I F I difficult to allow for such an error. 250 The results presented here show that K 20O work is still needed to improve the characterization of the known long- 150- term thermosphere variations by the g models. 100- O p ,..__-- 50 I I I I I I I Wilson, R.M. 1992. An Early Estimate for 46,400 46,600 46,800 47,000 47,200 47,400 47,600 47,800 48,000 the Size of Cycle 23. Solar Physics 140:181-93. Dec.I, 1985 April18,1990 ModifiedJulianDay

Sponsor: Office of Space Flight and FIGUR_18.--Ratio of average densities calculated from the MSIS and JACCHIA Space Station Projects Office models to the average densities derived from the decay of LDEF. The individual data points are not shown but connected by the dashed line. The bottom panel shows the variation in radio solar flux during the rise of the current solar cycle.

33 Research and Technology 1993

Global Climate temperatures. Monthly data sets are Geophysical Fluid Flow Monitoring From now routinely provided to NOAA's Cell Experiment Satellites Climate Analysis Center.

Fred W. Leslie/ES42 In the last year, global tropospheric Roy W. Spencer/ES43 205-544-1633 205-544-1686 temperatures have remained below normal due to the June 1991 erup- The Geophysical Fluid Flow Cell tion of Pinatubo volcano in the Phil- Lower tropospheric and stratospheric (GFFC) Experiment simulates a wide ippines. The stratospheric aerosols temperatures, as well as oceanic variety of thermal convection phe- produced by this volcano reduced rainfall, are being monitored with nomena in spherical geometry. By the incoming sunlight by about the Microwave Sounding Units that applying an electric field across a 5 percent and caused the northern have been flying on the Televi- spherical capacitor filled with a di- hemisphere summer of 1992 to be sion Infrared Operations Satellite electric liquid, a body force analo- very cool. As of June 1993, the strato- (TIROS-N) series operated by gous to gravity is generated around spheric aerosols have mostly cleared NOAA. Data sets of these three pa- the fluid. The force acts as a buoyant out of the stratosphere. During their rameters are now being produced at force in that its magnitude is propor- peak, these aerosols also produced daily time resolution and 2.5 degree tional to the local temperature of the very warm temperatures in the lower latitude-longitude spatial resolution. fluid and in the radial direction per- stratosphere due to greenhouse trap- The data sets are of high quality and pendicular to the spherical surface. ping of upwelling infrared radiation valuable for a wide variety of In this manner, cooler fluid sinks weather and climate research. As emitted by the warmer lower atmos- toward the surface of the inner phere and surface of the Earth. As of part of the NASA Pathfinder pro- sphere while warmer fluid rises to- June 1993, the lower stratospheric gram, these data are being made ward the outer sphere. The value of temperatures have cooled off to available to the climate research this artificial gravity is proportional nearly record low levels. community. This will enhance our to the square of the voltage applied understanding of climate processes, across the sphere and can thus be such as global warming, the effects Sponsor: Office of Mission to Planet imposed as desired. With practical Earth of rainfall on the atmospheric gen- voltages, its magnitude is only a eral circulation, and the effects of fraction of Earth's and so requires a ozone depletion on stratospheric microgravity environment to be sig- nificant. The GFFC first flew on Spacelab 3, and has been scheduled for flight aboard the second United States Microgravity Laboratory (USML-2).

Research work is proceeding in computational and experimental geophysical fluid dynamics leading up to the reflight of the GFFC on USML-2. The work is intended to generate fundamental results con- cerned with nonlinear and chaotic properties of thermal convection and baroclinic waves in terrestrial and planetary atmospheres. The major efforts are focused on thermal con- vection relevant to Jovian atmos- pheric dynamics, and on the chaotic behavior of baroclinic waves relevant to the Earth's atmosphere and oceans. 34 Research Programs

This research has demonstrated, ways. This leads to strong quasi- between EOF's and dynamics? This using a quasi-geostrophic convecting periodicity and chaos in both nu- is a major question in atmospheric channel model, that large scale zonal merical simulations and experiments, science. In the baroclinic wave chaos jets could be generated by convec- and may be an important process in problem, not only has the EOF tion with vertical shear. This model the atmosphere and the Antarctic method been useful in reducing the indicated that high wave-number Circumpolar Current. dimension of the models from over convection would only occur in a 104 to less than 30, but it has been shown where the EOF's come from narrow band of parameter space. Why is the large-scale atmospheric As the Rayleigh number (Ra) is in- motion chaotic? The canonical two- a priori. They can be related (by creased, short wavelength Beta con- layer Phillips model has been shown correlation analysis) to the secondary vection rapidly gives way to low to be only weakly chaotic at best. and tertiary linear instabilities of the wave-number convection. However Recent computational simulations equilibrated steady baroclinic wave at unit Prandtl number, such low of nonlinear baroclinic waves with fields. Thus they can be computed wave-number cells still tilt and can stress-free meridional barriers sug- a priori. In addition, this research has generate large mean flows. The basic gest that a crucial ingredient is shown that the long-term baroclinic result of wave-number cascade to meridional shear that can drastically wave fluxes in chaotic and turbulent low values as Ra is increased was reduce the critical Froude number regimes can accurately (within a few verified in a centrifugal convection for instability. In the oceanic context, percent) be determined by finding laboratory experiment where rapid rigid (no-slip) meridional walls of the the unstable fixed points of the rotation produces a centrifugal buoy- channel model have the counter- model. ancy perpendicular to rotation, yield- intuitive effect of rendering the two- ing an analog to the equitorial layer model subcritically chaotic. The experiments planned for the annulus. Some special fluid systems like ther- next flight of the GFFC are expected mohaline convection have been to further contribute to our under- Numerical models and laboratory found to be subcritically unstable. standing of these kinds of processes. experiments show that rigid side- This result is important for interpret- walls (as present in the GFFC and ing ocean eddy generation along Albaiz, A.; Hart, J.E.; and Leben, R. 1993. Earth's oceans) can play a very im- coasts by baroclinic instability. Flow Separation and Chaos in a portant role in the dynamics of non- Rotating Annulus. Computational linear instabilities and waves. Simple Empirical orthogonal functions Fluid Dynamics, 21 pages, in press. (EOF's) were proposed many years experiments with barotropic motion Brummell, N., and Hart, J.E. 1993. High ago as a tool for analyzing atmos- in an annulus showed that separa- Rayleigh Number Beta-Convection. tion of the sidewall boundary layer pheric data. Recently they have been Geophysical and Astrophysical Fluid can lead to chaotic motions and used in models to extract self-consis- Dynamics 85:114. strong vortices in the interior of a tent, low-order dynamical systems rotating fluid. In addition, when local from the full equations of atmos- Mundt, M., and Hart, J.E. June 1993. separation or instability occurs that pheric dynamics. Besides perhaps Secondary Instabili W, EOF's, and Baroclinic Chaos. To be submitted is locked topographically to a parti- being useful in building low-order climate models, such methods can to the Journal of Atmospheric cular longitude, and when the over- Science. all geometry is convected (cyclic), yield useful interpretations of the then a zonal teleconnectivi W can dynamics. However, the pattern Sponsor: Office of Mission to Planet arise where vortices generated in recognition algorithms used to find Earth the instability region can propagate the EOF's have nothing to say dy- around the annulus and influence namically about where they may the local generation region in various come from. What is the connection

35 Research and Technology 1993

The Advanced Microwave Atmosphere (TOGA) Coupled order to improve calibration accuracy. Precipitation Radiometer Ocean-Atmosphere Response Experi- The data acquisition unit, using tape ment (COARE). Ground-based opera- cartridges as a data storage medium, tions for the ER-2 were conducted in Robbie E. Hood/ES43 was replaced with a system using 205-544-5407 Townsville, Australia, while flight flash random access memory (RAM) operations were directed to the west- cards in order to improve flight har- ern Pacific Ocean region between 20 diness and reliability. The ground- The Advanced Microwave Precipita- tion Radiometer (AMPR) and its ac- degrees North and 20 degrees South, based data processing workstation bounded by Indonesia on the west companying data acquisition system was also upgraded to produce higher and the international date line on the fly aboard a NASA ER-2 high-altitude resolution color images of AMPR east. TOGA COARE was an interna- aircraft to collect passive microwave data and speed up post-flight data tional experiment with representa- upwelling emissions from the Earth's analysis. The AMPR performed suc- tives participating from 15 nations. surface and atmosphere. The instru- cessfully during 15 data collection The overall research objective was to ment is a cross-track scanning, total- missions, many of which were at power radiometer with four channels improve our understanding of the least 8 h in duration. Various types relationship between the warm water centered at 10.7, 19.35, 37.1, and and aspects of oceanic rain systems 85.5 GHz. The AMPR utilizes a rotat- pool found in this region of the were sampled. Tropical cyclone western Pacific and the mean and ing polarization that varies from a Oliver was also studied during devel- transient behavior of the global at- vertical component at 45 degrees to oping, maturing, and dissipating mosphere system. Specific NASA the left of nadir, to equally mixed stages. These TOGA COARE AMPR objectives during this experiment components at nadir, and finally to a data will be reviewed and quality supported both the TOGA COARE horizontal component at 45 degrees documented during the next year. research goal and the Tropical Rain- These data will then be archived at to the right of nadir. The surface fall Measuring Mission (TRMM) as resolution of the nadir-viewing foot- those NASA Earth-Observing System part of the NASA Mission to Planet prints ranges in size from 2.8 km for Data and Information System Earth. AMPR data will be pertinent to (EOSDIS) Distributed Active Archive the 10.7 and 19.35 GHz channels, to TRMM objectives related to studies of Centers (DAAC) that maintain cata- 1.5 km for the 37.1 GHz channel, and 0.64 km for the 85.5 GHz chan- tropical oceanic precipitation clima- logs of passive microwave and tology, vertical structure of precipita- TOGA COARE information. nel when collected at a high-altitude aircraft height of 20 km. tion hydrometeors, and physical processes associated with $1_k_or: Office of Mission to Planet precipitation. Earth The AMPR was deployed along with other microwave instrumentation In preparation for TOGA COARE, the aboard the NASA ER-2 during AMPR external calibration loads were January and February 1993, as part upgraded to a design similar to the of the Tropical Ocean Global loads used by the DMSP SSM/I in

36 Research Programs

Multispectral 0.5 to 0.9 K. In 1986, the configura- consists of off-the-shelf components tion was changed to improve the and custom software running on a Atmospheric Mapping NEAT's down to the 0.3- to 0.5-K personal computer. The MAMS Sensor range. This resulted from having a instrument was recently upgraded by larger aperture of 5 mrad that pro- NASA's Ames Research Center to duced a 100-m IFOV at a scan rate of Mark W. James/ES43 allow recording of the data on 8-mm 205-544-5020 6.25 r/s. The slower scan speed and tape cartridges, rather than the larger larger aperture allowed more radiant format 14-track instrumentation tape energy to fall on the detectors and recorder systems used previously. NASA's Multispectral Atmospheric increased the integration period, With this upgrade of the data format, Mapping Sensor (MAMS) is a line improving the NEAT's of the thermal the interface was changed from a scanner with eight visible and three channels. The scan head or primary single-channel bit and frame syn- IR channels. (There are actually four optics used by the MAMS spectrom- chronization card mounted in the IR channels; however, only three are eter is also used by other spectrom- personal computer, to an 8-mm tape available at any one time on the eters such as the Thematic Mapping drive interfaced to the personal com- scanner.) The visible channels range Sensor (TMS), the Advanced Ocean puter by a Small Computer Systems from 0.42 to 1.05 _m, with the IR Color Imager (AOCI), and the Interface (SCSI). This new data input channels varying from 3.47 to MODIS-N Airborne Simulator (MAS). allows all channels to be entered 12.71 !tim. Several changes that directly affect line-by-line with one pass through data quality have been made to the the tape. Added flexibility in selec- Only three of the IR bands are avail- scanner system to accommodate the tion of channels to look at while able during any configuration, and AOCI spectrometer. These changes ingesting data will improve the anal- the 6.54- and 3.73-1am bands cannot have improved data quality in all ysis aspect of the QVS capabilities by be used together (table 2). MAMS scanner applications. The axe-blade providing more data to select from data are being used to determine scan mirror was upgraded to a full- without multiple passes through the atmospheric moisture variability and face mirror. This change increased tape. The system will utilize the its importance for cloud formation the amount of energy falling on the Exabyte tape drive capability of over and storm development at scales not detectors and increased the signal-to- 500mb/s sustained read rate. available from satellites. The MAMS noise ratios in all channels. With instrument is flown aboard NASA's Jedlovec, GO.; Batson, K.B.; Atkinson, the improved dynamic range, the ER-2 high-altitude aircraft where R.J.; Moeller, C.C.; Menzel, W.P.; and digitization resolution was upgraded data are recorded on an Exabyte James, M.W. 1989. Improved Capa- from 8 to 10 b for the IR channels. 8-mm tape cartridge. bilities of the Multispectral Atmos- The averaging electronics for the pheric Mapping Sensor (MAMS). blackbodies were also changed to NASA Technical Memorandum TABLE2.--IR channel information average over more samples of the 100352. (Available from the National blackbodies to reduce the sensitivity Technical Information Society (NTIS) Channel Central Bandwidth(!Lm) of the detectors to noise. With these N-20430.) NASA, MSFC, AL. improvements, sensitivity became Jedlovec, GJ.; James, M.W.; Smith, M.R.; Wavelength (at 50% response] less than 0.1 K, with NEAT less than and Atkinson, RJ. The MAMS Quick 0.2 K. Based on current instrument 9 I 3.73 3.47-3.86 View System-2 (QVS2): A Worksta- performance, minimal changes are I tion for NASA Aircraft Scanner Data 10 I 6.54 6.28-6.98 necessary for collection of high- Evaluation. Preprints: 198-203. I quality data in the future. Seventh International Conference on 11 I 11.12 10.55-12.24 Interactive Information and Process- 12.56 12.32-12.71 When the instrument was taken to ing Systems for Meteorology, 12 the field for deployment, a defi- Hydrology, and Oceanography, ciency in on-site data analysis capa- American Meteorological Society The baseline system flown in 1985, bilities for scientific and engineering (AMS). Boston, MA. consisted of a 5-mrad aperture that evaluation of the MAMS data was Sponsor: Office of Mission to Planet produced a ground instantaneous lacking. The MSFC quick-view sys- Earth field of view (IFOV) of 50 m. With tem (QVS) was developed to provide the scan mirror rotation of 12.5 r/s, a near real-time analysis capability the noise equivalent change in by reading data directly from the temperature (NEAT) ranged from data tape after each flight. The Qvs

37 Research and Technology 1993

Multicenter Airborne wind estimates is obtained within suring global tropospheric wind Coherent Atmospheric the scan plane. Multiple scan planes, fields, is being developed by MSFC. Wind Sensor revealing a 3-D view of the velocity Ground-based lidar studies provide and backscatter structure, are ob- limited insights, thus influencing tained by appropriately directing the LAWS performance simulations. Jeffry Rothermel/ES43 scanner during flight. Aircraft attitude MACAWS will be used to duplicate 205-544-1685 and speed contributions to the radial the LAWS measurement perspective, velocity measurements are elimi- thereby providing unique informa- Development continues for the nated using information provided tion not present in ground-based Multicenter Airborne Coherent Atmos- by a dedicated inertial navigation observations. For example, LAWS pheric Wind Sensor (MACAWS). The system. data will contain a surface return 4-yr project will culminate in 1995, signal useful for calibration, atmos- with an airborne scanning pulsed Following aircraft integration and pheric extinction estimation, and CO 2 Doppler lidar for multidimen- check flights, MACAWS will be de- "ground-truth" velocity estimates. sional wind and calibrated aerosol voted to a series of specialized field This information can be used to backscatter measurement from the measurements designed to improve minimize biases in LAWS measure- NASA DC-8 research aircraft. understanding of atmospheric dy- ments; airborne studies with MACAWS is under joint development namic processes over critical scales MACAWS can provide insight into by the lidar remote sensing groups of motion within the boundary layer developing the necessary LAWS of NASA's MSFC and JPL, and and free troposphere. Specifically, algorithms. Other LAWS performance NOAA's Wave Propagation Labora- MACAWS wind measurements will issues that will be addressed are tory. MSFC has lead responsibility for contribute toward improving param- impact of spatial variability on veloc- overall coordination, science defini- eterization schemes for subgrid scale ity and backscatter sampling, de- tion, and mission planning. To mini- processes represented within climate tailed cloud properties, Doppler mize costs, each organization is and general circulation numerical estimation (particularly near aerosol sharing major hardware components models. Additionally, measurements gradients), and long-term monitoring and subsystems which, in nearly all with MACAWS will also contribute of natural surfaces that may serve as instances, have been used in previ- toward: improved understanding of potential calibration targets for back- ous ground-based or airborne orographic windstorms, generation scatter estimation, as well as for applications. of instability along dry lines, evolu- monitoring instrument health. Of tion of mesoscale circulations in course, an airborne lidar system, that The principal of operation is similar differentially heated boundary layers, can simulate the LAWS perspective to that successfully employed by interaction of thunderstorms with the could be applied to post-launch MSFC in previous airborne lidar environment including generation of performance validation studies as experiments. In operation, a pulsed new convection by thunderstorm well. lidar beam is generated and precisely outflows, regional air quality degra- directed anywhere within a 64-de- dation, and land surface processes. Rothermel, J.; Hardest-y, R.M.; and Menzies, R.T. March 8-12, 1993. gree cone using a scanning device The unique measurement capability Multicenter Airborne Coherent At- mounted on the interior left side of of MACAWS will contribute to the mospheric Wind Sensor. Preprints. the aircraft.The backscattered, Dop- improvement of predictive capabili- Topical Meeting on Optical Remote ties for weather and climate. pler-shifted radiation is measured to Sensing of the Atmosphere. Salt infer the line-of-sight wind velocity, Lake City, UT. assuming the aerosol scattering par- Additionally, MACAWS will be ap- ticles act as passive wind tracers. By plied to reduction of uncertainties in Sponsor: Office of Mission to Planet Earth scanning the lidar beam slightly performance of the Laser Atmos- forward and aft during flight (i.e., pheric Wind Sounder (LAWS). LAWS, "co-planar scanning") a field of 2-D a spaceborne Doppler lidar for mea-

38 Research Programs

Space Shuttle Lightning Research

Otha H. Vaughan, Jr./ES43 205-544-1648

The MSFC space shuttle Mesoscale Lightning Experiment (MLE)--flown on earlier shuttle flights and, most recently, on STS-31, -37, -35, -38, -41, -40, and -48--has continued t{} focus on obtaining additional quantitative measurements of light- ning characteristics and created a data base for use in demonstrating observation simulations for future spaceborne lightning mapping systems.

During the earlier shuttle flights, the MLE concentrated on obtaining a vide{) of lightning that was occurring directly below the spacecraft. A con- siderable amount of data was ob- tained showing large thunderstorm cells with lightning and frontal com- plexes, and the large amount of lightning that was occurring within these complexes. During some of the shuttle flights, a new phenomenon was observed by the low-light-level TV cameras as they monitored thun- derstorms near the limb of the Earth and its airglow. The phenomenon was a shaft-like discharge moving vertically out of the top of a thunder- storm. It had been observed while conducting the MLE as the shuttle FIGURE19.--Various types of vertical lightning as seen by a was orbiting over Africa, Australia, shuttle payload bay low-light-level TV camera. South America, and the United States during the nighttime passes over observation techniques and simula- discharges that could be occurring in active thunderstorms. At the present tions for future satellite missions, other planetary atmospheres such as time, the cause of this type of light- such as the TRMM that is now sched- Venus, Jupiter, Saturn, and Neptune. ning discharge is not known. uled to carry the Lightning Imaging Sensor (LIS) being developed at Vaughan, O.H., Jr.; Blakeslee, R.J., To date, a total of 17 vertical lightning Boeck, W.L.; Vonnegut, B.; Brook, discharge-type events have been MSFC. This type of research can M.; and McKune, J. July 1992. Pic- observed using the shuttle low-light- provide other researchers with a data ture of the Month: A Cloud to Space level TV cameras. Figure 19 shows base for use in understanding terres- Lightning Discharge as Recorded by some of the vertical-type discharges trial lightning processes, as well as the Space Shuttle Payload Bay TV that have been observed. These help in the understanding of light- Cameras. Monthly Weather Ret,iew shuttle video observations are to be ning processes on other planets. The vol. 120, no. 7:145_1. cloud-to-stratospheric lightning-like continued on future flights on a Sponsor= Office of Mission to Planet noninterference basis. These data discharges, or what may be called Earth will continue to provide information vertical lightning, may be more rep- for use in the development of resentative of the type of lightning

39 Research and Technology 1993

Aircraft Investigations Lightning rates, distribution, and coordination was obtained with of Lightning characteristics (i.e., number of aircraft (NASA ER-2 and DC-8, and and Thunderstorms strokes per flash, ratio of intracloud NOAA P-3's) and ship-based multi- to cloud-to-ground lightning, dis- parameter observations. Additional charge energy, etc.) are all factors lightning coverage was provided by Richard J. Blakeslee/ES43 that may prove useful in devising an island-based lightning detection 205-544-1652 quantitative algorithms, and these network. factors can be studied appropriately In recent years, observations of with the ER-2. Earlier (July and August 1991), ER-2 lightning and thunderstorms from science flights were conducted as Lightning instruments have now high-altitude U-2 and ER-2 aircraft part of the Convective and Precipita- have furnished data essential for the been integrated on the NASA ER-2 tiort/Electrification (CAPE) experi- design and development of satellite- and DC-8 aircraft. This lightning ment. CaPE provided extensive instrumentation detects total storm based lightning detectors and have multiparameter data sets referred to supported investigations of light- lightning and differentiates between above. More importantly, two of the intracloud and cloud-to-ground dis- ning relationships. This research is major scientific goals of this experi- charges. The lightning instruments motivated by the desire to develop ment coincide with primary objec- are also flown with other sensor an understanding needed for the tives of the ER-2 investigations and effective utilization and interpreta- systems (e.g., infrared, passive mi- NASA's overall lightning program. tion of data from the Optical Tran- crowave, Doppler radar, etc.) to These goals are: (1) the identification sient Detector (OTD), the Lightning provide new understanding of thun- and investigation of the relationships Imaging Sensor (LIS), the Lightning derstorms and precipitation and among the co-evolving wind, water, Mapper Sensor (LMS), and other support detailed satellite simulations and electrification within the convec- satellite-based lightning detectors of storm measurements through the tive cloud; and (2) rainfall estima- planned for the 1990's and early acquisition and analysis of multipa- tion. A large number of storm 2000's. rameter data sets. By developing and overflights were obtained during maintaining the capability to monitor The emphasis, now, is to quantify CaPE including a number of cases lightning and thunderstorms with the lightning relationships that have of multiple storm passes. In February these aircraft, NASA will also be able been determined. It is hoped that and March 1992, the ER-2 partici- to provide important ground-truth as a result of these kinds of investi- pated in the Storm-scale Operations verifications and calibrations when gations, lightning data alone or in and Research Meteorology-Fronts the OTD, LIS, and other lightning conjunction with other remote sens- Experiments Systems Test (STORM- detectors begin operations. ing techniques will provide quantita- FEST). STORM-FEST provided an tive information about such storm In January and February 1993, sci- opportunity to study wintertime thunderstorms. characteristics as the occurrence ence flights were conducted during and location of embedded convec- the international TOGA COARE Sponsor: Office of Mission to Planet tion, the strengths of updrafts and program to investigate electrical Earth downdrafts, thermodynamic and processes of tropical maritime con- electrical energy budgets, precipita- vection and support multisensor tion amounts and distributions, and precipitation algorithm development. atmospheric chemistry processes. During TOGA COARE, excellent

4O Research Programs

Lightning Imaging Sensor waves to x rays. One of the strongest This signal processor performs real- radiation regions is at visible wave- time discrimination between light- lengths, which accounts for almost ning events and the background, Hugh J. Christian/ES43 compressing the total data rate by 205-544-1649 1 percent of the total energy re- leased: 100 to 1,000 mW of light. almost a factor of one million. These optical emissions result from The Lightning Imaging Sensor (LIS) As part of the Mission to Planet the dissociation, excitation, and sub- is currently under development for Earth, LIS and OTD will provide sequent recombination of atmos- flight on the TRMM, scheduled for unique data leading to a global cli- pheric constituents that are primarily launch in 1997. In addition, an engi- matic lightning data base from which affected by electron b()mbardment neering model of the LIS is being changes in the distribution and fre- and the sudden heating of the chan- assembled, tested, and calibrated quency of lightning can be studied nel. The heating is so intense that for flight. Once qualified, this instru- and related to the physics of the emissions occur primarily at discrete ment-the Optical Transient Detec- atmosphere that are responsible for atomic lines, with some continuum tor-will be integrated onto a these changes. In addition, LIS will at shorter wavelengths. The strongest Microlab-1 spacecraft and launched contribute toward improving the emission lines are produced by neu- by a Pegasus vehicle in 1994. This understanding of the interrelation- tral oxygen and nitrogen, and occur will provide a lightning data set ships between lightning and convec- in the near infrared, from 7,774 A to 3.5 yr earlier than the TRMM, will tive precipitation, clarify the role of 8,683 A. be highly complementary to the lightning in the production and dis- TRMM, and will demonstrate both tribution of trace gases, help investi- the value of global lightning data The LIS is a staring imager that is gate the mechanisms for electrical and the accuracy of LIS-specific optimized to detect and locate light- coupling of lightning with the iono- scientific algorithms. ning events. It images a scene in sphere and magnetosphere, and much the same manner as a televi- provide a mechanism for investiga- The LIS uses an innovative optical sion camera; however, because of ting the Earth's global electric circuit design that has been optimized for the transient nature of lightning, its by quantifying the electrical variables the unique signal produced by light- spectral characteristics, and the diffi- and determining their relationship to ning. Lightning is accompanied by culties of daytime detection, actual the currents that flow within and the sudden release of electrical en- data handling and processing differs near thunderstorms. ergy that is converted into rapid vastly from that required by simple images. The heart of the LIS consists Sponsor: Office of Mission to Planet heating in the vicinity of the channel, Earth the generation of a shock wave, and of a large mosaic-array, focal-plane electromagnetic radiation ranging assembly, tightly coupled to high- from extremely low-frequency radio speed processing electronics.

41 Research and Technology 1993

Sensor Development: Lightning Imaging OpticalFiberBundle.-_ Sensor Calibration ;_LIS FocalflaneAssem_ I Monochromalort Mark W. James/ES43 Real-limeEvent 205 -544-5020 ¢_ Processor F_olPlaneDin, Vi&o Two-AxisGimbal The Earth System Observing Branch {ComputerControlled) of the Earth Science and Applications Division is supporting the develop- ment of electro-optical instrumenta- FIGURE20.--LIS spectral calibration system. tion for space applications. Under the Earth Observing System (EOS) performed on the sensor to verify current (ac) linearity test is designed program, an optical facility is being alignment of the lens assembly to the to allow the entire system to be developed to calibrate the Lightning focal plane, iinearity of each pixel, tested from end-to-end. The tests up Imaging Sensor and to measure its responsitivity of each pixel, and to now are being performed collect- performance through the use of characterization of the narrow-band ing data right off the focal plane and realistic simulations. The LIS will filter. Uniformity and linearity of are considered direct current (dc) image the large-scale distribution each pixel will be accomplished tests. The real-time event processor of lightning from low-Earth orbit using a large integrating sphere illu- (RTEP) will only respond to light- in a 1-nm wide, near-infrared minated with a constant light source. ning events that are ac events from (NIR) wavelength band using a The source's intensity will be ad- the focal plane. The ac linearity test 128- by 128-pixel silicon (Si) charge justed by a controlled aperture to will allow both signal paths to be coupled device (CCD) focal plane ensure constant brightness tempera- tested by building upon the funda- array. The sensor is being designed tures. Spectral calibration using the mental dc linearity test. Also, to en- to detect lightning during both low- Jones Method of near-field small sure that no additional energy will background (nighttime) and difficult, source will allow a determination affect the intensity in each pixel by high-background (daytime) condi- of the narrow band filter width using being out-of-band, a test will be tions, when the background flux a high-resolution (760-800 nm at performed to verify the out-of-band exceeds the signal by many orders of 0.1 nm) monochromator. The instru- rejection of the narrow band filter magnitude. The instrument specifica- ment will be coupled to the mono- since the pixel's response is some- tions also include a 2-ms frametime chromator through a fiber-optical what sensitive at or near the filter and a field of view of approximately bundle with a defocused image to edges of 150-1,500 nm. This will be 80 by 80 degrees. allow entire pixel coverage (fig. 20). accomplished using a board-band The LIS will also be mounted on monochromator to flood a small The calibration facility is currently a two-axis gimbals stage to allow integrating sphere with enough en- supporting two distinct test systems the entire focal plane to be slow ergy to allow an indication of a that can be defined as radiometric scanned. The test will cover approxi- problem in the filter and later using calibration and lightning scene simu- mately 350 to 1,100 nm to ensure the high-resolution monochromator lation. Radiometric calibration will be coverage of the filter. The alternating to characterize, if necessary.

42 Research Programs

The lightning scene simulator will Advanced Technologies temperature ranges from room use a 3-mW NIR diode laser as the for Geostationary Orbit temperature to below 90 K. Scientists at MSFC are developing a 0.5-m source of simulated lightning. Using Remote Sensing a mirror scanner for positioning, the telescope in which all mirrors and laser beam will be pulsed and structural elements are made from scanned across a rear projection Ronald J. Koczor/ES41 silicon carbide. 205-544-3078 screen to simulate a dynamic light- ning scene. A static background Diffractive optics have a variety" image can also be projected onto the The Geostationary Earth Observatory of potential applications within screen and its intensity varied by the will be an important component of spacebome remote-sensing instru- NASA's Mission to Planet Earth. It will ments. While not suitable for the use of neutral density filters. A simple combination of plastic field include several optical instruments to front-end reflective telescopes that monitor the Earth's environment lenses and collimating lens is used are typically used to collect energy to place the lightning scene at the from the perspective of geostationary in multispectral remote sensors, infinite conjugate plane and to ob- orbit and will serve as a complement diffractive optics can be used to tain wide FOV coverage. The antici- to NASA's Earth Observing System in create hybrid diffractive/refractive pated FOV coverage will be 70 by low, polar orbit and other Mission to lens elements (resulting in poten- 70 degrees. Planet Earth flights. tially simpler imaging systems), polarization control elements, and The geostationary orbit imposes a antireflection structure surfaces A 486-based compatible computer is severe thermal environment on any for windows, spectral filters, and being used as the central processor optical instrument that is on a three- detectors. Complex optical elements for image capture and control of the axis-stabilized spacecraft. At the (having aspheric and high-speed laser beam onto the focal plane. same time, optical resolution require- surfaces) can be made physically High-speed data acquisition modules ments are higher in geostationary simpler and with better performance. are being utilized to position the orbit than in low-Earth orbits (for MSFC also is developing a refractive/ mirror scanner through a windows- comparable ground resolution) be- diffractive optic for use in lightning based positioning system. The cap- cause of the orbit's farther distance sensing from geostationary orbit. tured frame received from the LIS from Earth. The Earth's rotation (and will be compared against the image the rotation of the spacecraft over Research is under way to develop map in the computer used to posi- the Earth) allows direct solar flux these advanced optical technologies tion the laser and adjust the intensity onto the optical ports of Earth-view- to the point where they can be used of the beam. The lightning scene ing remote sensors for periods of for the GEO remote-sensing instru- simulator is complete and will test several hours each day. The higher ment complement to provide un- the engineering model of the sensor thermal and optical performance precedented performance under the starting in October 1993. required of instruments in this orbit severe environment of the GEO. can take advantage of research pres- Sponsor: Office of Mission to Planet ently under way in several new tech- Koczor, R.J. April 12, 1993. Technology Earth nology areas, including silicon Needs for Geostationary Remote carbide and composite optics and Sensors. Proceedings, SPIE cbnfer- ence on Sun,eillance Technologies structures, diffractive optics, and and Imaging Cbmponents vol. 1952. chip-scale image motion compensa- tion systems. Sponsors: Office of Commercial Silicon carbide is a serious alternative Programs, Small Business Innovation to beryllium for spacebome, light- Research Program; and Office of Mission to Planet Earth, Radiation weight telescope and mirror applica- tions. It has excellent thermal and Dynamics Branch properties, significantly lower cost, Commercial Involvement: SSG, and simpler, nontoxic fabrication Inc., and Rochester Photonics, Inc. processes. Surface thermal stability of better than 0.25 wave of visible light has been demonstrated over

43 Research and Technology 1993

III I I Space Physics

The Mechanisms of Solar of their magnetic flux, as opposed to is why they are so important to Variability--A Study diffusion, which is critical to further understanding atmospheric chemistry development of dynamo theory. of the Origins of the and have to be observed from space. Observations of the hot upper levels Variability of the Solar These goals may be achieved in a of the solar atmosphere will be ob- Output series of steps, each of which is tained using suborbital flights on expected to provide incremental sounding rockets. This approach advances in the technology and facilitates the rapid incorporation of John M. Davis/ES52 scientific knowledge needed to un- 205-544-7600 new technology into the instrumen- derstand solar variability. The initial tation, and the flights can easily be step will be to develop a large bal- coordinated with the flight of the The goal of the Mechanisms of Solar loon-borne optical telescope operat- balloon observatory. Variability (MSV) program is to im- ing in the visible spectral region. A prove our understanding of the mag- mirror diameter of 1 m will be re- The results from the MSV will indicate netic connection to solar variability. quired to overcome the diffraction the directions for future study, which By following a focused program of limit at the required resolution, and theoretical models are worth pursu- theory and observation, with the it will be carried to balloon altitudes ing, and which observations are latter having ground-based, subor- in excess of 125,000 ft to minimize needed to confirm ideas or to differ- bital, and space flight elements, sci- the atmospheric disturbances--gen- entiate between competing views. entists at MSFC expect to achieve a erally referred to as "seeing"--which The engineering and scientific expe- better understanding of this connec- plague ground-based observations. rience gained in developing and tion. The observational objective is The telescope will be outfitted with applying the needed technologies, to break the spatial resolution barrier advanced focal plane instrumenta- and for operating and analyzing the at a few tenths of an arc second and, tion, including high-resolution spec- scientific data from the meter-class in doing so, resolve and image for trographs, polarimeters, tunable observatory, will form the basis for the first time the individual magnetic filters, and large format CCDcameras. developing a major space mission flux tubes that comprise the solar This approach allows for interchange- (the Advanced Solar Mission) at magnetic field at the photospheric able focal plane instrumentation that lower risk and cost than could level. The images will contain diag- is expected to be developed at dif- otherwise be achieved. nostics of the vector magnetic field ferent institutions, ensuring broad MSV is designed to be broadly based and the plasma velocities and will involvement in the program. As a allow scientists to determine how the and rapidly implemented. Universi- balloon-based observatory, achiev- ties and their students will be fully individual flux tubes evolve, interact, ing shorter instrument development and coalesce, and how energy is cycles than are possible with space- involved in all aspects, from concep- tual design, through development transferred between the surrounding craft programs are expected, thus plasma and the magnetic field. and flight, to analysis of the scientific allowing incorporation of rapidly data. The timeline for these activities developing technology into the is consistent with courses of study The specific scientific objectives to program. be addressed by MSV include testing for advanced degrees. In a wider sense, the images of the immense models of coronal heating by deter- The balloon telescope will provide structures present in the solar atmos- mining how the chromosphere and data on a rather narrow range of phere revealed by scientific observa- corona are magnetically linked to, heights in the solar atmosphere from tion, have a powerful impact on all and driven by, the photosphere on the photosphere, which is the visible the scale of individual magnetic flux surface, to the low chromosphere. who see them, not only because of their inherent beauty, but because tubes; providing a quantitiative This is a result of the rapid increase physical understanding of the Sun's in temperature of the solar atmos- they unveil a view of the physical world that is totally unexpected. The luminosity variation by tightly con- phere with height. At these high fact that the behavior of these struc- straining models of individual photo- temperatures the solar atmosphere tures affects life on Earth provides a spheric flux tubes; testing the belief radiates energy at wavelengths readily understandable insight into that solar flares are releases of an shorter than the visible, ranging from the importance, and relevance to active region's stored magnetic en- the ultraviolet to soft x-ray regions. society, of scientific discovery. ergy; and determining whether active These radiations are absorbed high regions disappear by submergence in the Earth's atmosphere, which $1_nsor: Office of Space Science

44 Research Programs

Solar Magnetic Fields of the light of a magnetic-sensitive and testing camera performance. spectral line. Through proper analy- Furthermore, the accomplishments sis, the polarization measurements include: testing the EXVM Fabry- Gilmer A. Gary/ES52 Perot filter at the National Solar 205-544-7609 yield the magnetic vector field at the photosphere. In connection with this Observatory (Sacramento Peak Ob- The mechanisms that create solar instrumentation, various MSFC solar servatory); design and fabrication of programs have been undertaken in the EXVM solar correlation tracker; variability must be anchored in the support of NASA projects and in completion of extensive tests of physics of the solar magnetic fields and electric currents since the forces support of collaborative observations EXVM polarimeter; completion of (i.e., Skylab, Solar Maximum Mission arising from their interaction domi- optical design and polarization nate over all other forces in the solar (SMM), Spacelab, Flares '91, Max '91, analysis for a balloon-borne 60-cm Yohkoh, Mechanisms of Solar Vari- telescope; study of options for high- atmosphere. The magnetic field plays ability (MSV)). These solar programs density, low-power data storage the most important role in determin- have included: (1) theoretical and devices for a balloon EXVM; and a ing the Sun's changing behavior and observational studies to perform study of a video telemetry system has a direct impact on the Earth's basic research in solar magnetic for a balloon EXVM In basic re- environment. Understanding the fields, (2) instrumentation develop- search, correlations of photospheric physical cause of the UV and x-ray variations in radiation from the solar ment using new polarimeter tech- motions, magnetic field ew_lution, niques, (3) observations with and buildup of magnetic shear in atmosphere (photosphere, chromo- supporting advance data reduction, two major flare-productive active sphere, and corona) is important in and (4) programs to predict the regions have been studied. The mag- that radiation produces effects in the probability of major solar flares. The netic structure for the June 1991 Earth's upper atmosphere, thereby important effort currently is the de_ region has been investigated. Movies producing effects on the Earth. velopment of a breadboard instru- of the vector magnetic fields with Hence, in solar physics, one major mentation to test orbital and coaligned H-alpha images for this aim is to define the solar magnetic suborbital flight components of a region that produced five gigantic field's topology and evolution in state-of-the-art vector magnetograph. X-class flares have been developed. order to understand both the large Various technical details are now Evidence has been produced for and small variability of solar radia- being carried out. changes in the vector magnetic field tion. However, the role of the mag- as a result of solar flares. MSFC sci- netic field is still enigmatic, and Recent accomplishments include: entists have collaborated with the careful study is needed. In this effort, the testing of the complete optical Yohkoh's investigators in under- MSFC solar scientists have developed system of a new Experimental Vector standing the magnetic structures of unique instrumentation that provides Magnetograph (EXVM), installations the Sun. knowledge on the structure of our of electronics in the EXVM CCD Sun. camera system and data system, The mathematical analysis of the The ground-based MSFC Solar Vector completion of mechanical designs extrapolation of the observed mag- Magnetograph is an internationally for the EXVM and a conceptual netic field continues to be an impor- recognized instrument for deriving assembly drawing for the EXVM tant part of the solar studies. The the magnetic structure and electric mounted to a stratospheric balloon modern mathematical technique of currents on the Sun. The Vector Mag- gondola, analysis of the instrumenta- regularization has been investigated netograph is a telescope that has a tion of polarization of the EXVM in order to provide a computation unique focal plane detector. The de- optics, installation of four 1024- by tool to allow MSFC scientists to tector measures the total polarization 1024-CCD chips in the EXVM camera, model the structure of the magnetic

45 Research and Technology 1993

6O

5O

4O

aO

20

10

10 20 a0 40 50 60

AR6555 March24, 199# (TransverseVector Field)

FtGURE2 1.--I-intensity contours. field and the associated electric cur- Research continues on the connec- suborbital magnetographs that are rents in the solar corona. As part of tion between the magnetic field and needed for the advancement of all of the physical and mathematical stud- solar activity through ground-based solar science. The EXVM will permit ies of the Sun, MSFC scientists have observing campaigns and special the measurement of solar magnetic been invited to participate in various research projects in the analysis of fields with the highest accuracy that international conferences. MSFC solar magnetograph data (fig. 21). Daily modern technology and data analysis scientists continue to collaborate observations are being taken and allow. with the international community, analyzed for Yokhok mission plan- participating in a two-way flow of ning and analysis, and for Max '91 Sponsor.- Office of Space Science information on all aspects of solar campaigns. These important studies physics. will define the NASA orbital and

46 Research Programs

Corona and Solar Wind

Ronald L. Moore/ES52 205-544-7613

The Sun's extended outer atmosphere, the corona, is so hot that it radiates predominantly in x rays and continu- ally explodes out past the planets as the solar wind (fig. 22). The persis- tent heating that nmst be present to sustain the hot corona and solar wind is a long-standing premier problem of solar physics. The Sun's coronal luminosity is of the order 1,028 erg/s. X-ray emission of this order or greater, and having the spectral and ternporal character of that from the Sun, has been ob- served to be normal for nearly all stars that, like the Sun, have convec- tive envelopes. From this evidence it is now" accepted that a hot corona similar to the solar corona is a com- mon feature of these stars, and the F,GURE22.--The Sun's corona and solar wind. problem of coronal heating has become a focus of solar-stellar gas pressure alone. An additional the solar wind. This picture requires astrophysics. driver is needed to account for the a dissipation mechanism that works observed speeds and mass fluxes of on the reflected Alfven waves much more than on the unreflected ones. The solar corona is permeated by the solar and stellar winds. This is a magnetic field that is rooted in, another major problenl of solar- During the past year, these scientists generated by, and continually stellar astrophysics. have identified a promising mecha- changed by the convective envelope. nism for selectively dissipating the Over much of the surface of the Sun, During the past year, a group of reflected waves, "intermittent mag- this magnetic field is in the form of solar astrophysicists from MSFC, the netic levitation," which is a conse- closed loops that confine the coronal UniversiW of Alabama in Huntsville, quence of the reflection itself. plasma. But in some areas, the mag- and the University of Chicago have netic field is forced open by the continued to make progress on both These researchers have also consid- pressure of the hot coronal plasma. the coronal heating problem and the ered possible generation mechanisms From these open-field regions the solar/stellar wind problem by consid- for their proposed Alfven waves in coronal plasma expands and empties ering the reflection of Alfven waves coronal holes. One possibility is the out to fill interplanetary space with in a nonuniform medium, such as conversion of the vertical (p-mode) the outflowing solar wind. These in a coronal hole. Their results in oscillations of the Sun's surface (the open-field, relatively empty places in the previous few years suggested: photosphere) into Alfven waves the corona are seen as dark coronal (1) that the 106 K temperature in through interaction of the oscillations holes in x-ray images of the corona. coronal holes is maintained by heat- with feet of the coronal magnetic However, the observed solar wind ing by reflected Alfven waves having field in the upper photosphere and flow, and much more massive but periods of about 5 min or longer, low chromosphere. From a rough cooler winds observed from giant and (2) that AlDen waves with peri- estimate, they found that the energy stars with convective envelopes, ods shorter than about 5 min are not flux of Alfven waves generated in cannot be explained by the coronal reflected, but propagate on out into this way could be no more than of

47 Research and Technology 1993

order 105 erg/cm2/s, an order of an answer to each of these questions. Long-Term Solar Activity magnitude less than the flux needed They proposed that the wind tem- Predictions to heat the corona and drive the perature is set by coronal heating solar wind. During the past year, they by reflected Alfven waves as in solar completed and published measure- coronal holes, and that in evolving David H. Hathaway/ES52 ments (from specially tailored obser- across the dividing line, the domi- 205-544-7610 vations of the Mg I 4571 A line) of nant mode of the dynamo generat- the p-mode energy propagation up ing the magnetic field in these stars The analysis of 250 yr of sunspot through the photosphere. These changes from being globally orga- observations suggests that solar activ- measurements definitely show that nized (as for the field that emerges ity can be represented by a fairly the energy flux in the p-mode oscilla- to form the large solar bipolar sun- simple mathematical function, with tions decreases steeply with height in spot regions) to being local and only two or three parameters for the lower photosphere, to less than chaotic (as for the small solar ephe- each 11-yr sunspot cycle. It has been 105 erg/cm2/s in the upper photo- meral bipolar magnetic regions); the found, in fact, that each cycle can be sphere. This substantiates their previ- reduction in scale of the closed-field characterized by two parameters: the ous estimate and conclusion that the bipoles results in nearly all of the starting time for the cycle and the p-mode oscillations do not feed field on scales of the stellar radius in cycle amplitude. This mathematical enough power into AlDen waves to the stellar corona becoming open. function, then, provides a reliable heat the corona. Thus, they have description of the complete cycle. By found some encouragement for their Fontenla, J.M.; Rabin, D.; Hathaway, analyzing the previous 21 sunspot previously published suggestion that D.H.; and Moore, R.L. 1993. cycles, it has been found that these microflares low in the magnetic field Measurement of p-Mode Energy two parameters can be determined above the photosphere are the main Propagation in the Quiet Solar within about 3 yr of the start of the generators of the required AlDen Photosphere. Astrophysics Journal cycle. This, then, gives a reliable waves. (Ap. J.) 405:787. prediction of the level of activity for the remaining 5 to 12 yr of the cycle The progress of these researchers Moore, R.L.; Hammer, R., Musielak, Z.E.; and an estimate for the start of the over the past few years in gaining Suess, S.T.; and An, C.H. 1992. A next cycle. new understanding of reflection of New Way to Convert Alfven Waves AlDen waves in open-field regions into Heat in Solar Coronal Holes: Solar activity influences the Earth of stellar atmospheres (coronal Intermittent Magnetic Levitation. and near-Earth environment in Ap. J. 397:L55. holes) led them to propose that the many ways. Over the course of cool massive winds from late-type the last 11 yr the total energy out- Rosner, R.; Musielak, Z.E.; Cantaneo, F.; giant and supergiant stars were put of the Sun varied by about Moore, R.L.; and Suess, S.T. 1993. A driven by such reflection, and that, one-tenth of I percent. At the same Dynamo Explanation for the Disap- in the Herzsprung-Russell diagram time, the ultraviolet output varied pearance of Coronal X-Ray Emission by 3-4 percent and emissions at for these stars, the dividing-line tran- in Stars With Cool Massive Winds. higher energies had even larger sition from hot x-ray coronas to cool Nature, in press. massive winds results from a transi- variations. Although the small tion in the topology of the coronal change in the total output should Sponsor- Office of Space Science field from mainly closed to mainly not alter Earth's climate by any ap- open. This suggestion, by itself, of- preciable amount, there is evidence fers no explanation for: (1) the University Involvement- University that in the past the variations might of Alabama in Huntsville and Univer- 104-105 K temperatures of the cool have been larger and more influen- massive winds, or (2) the transition sity of Chicago tial. There is also evidence that other in the field topology. During the stars similar to the Sun exhibit larger past year, these scientists have found variations during their cycles. The more substantial changes observed in the ultraviolet output of the Sun influence the formation of ozone in the stratosphere, while the more energetic emissions influence the Earth's uppermost atmosphere, at spacecraft altitudes.

48 Research Programs

Monitoring and predicting solar 3.0 activity over the course of the solar cycle is important for the space pro- gram because it provides useful information for determining the or- bital decay of satellites and space- 2.0 based platforms such as a space station. A good determination of solar cycle variations is also useful for understanding the changes seen in the Earth's climate and strato- spheric chemistry. A better under- "_ 1.0 ,*a, standing of how the Sun produces a,, these variations should lead to a better understanding of how other stars behave, as well. Unfortunately, there are no good predictive theories I I I I I I for how the solar cycle works. How- t 2 3 4 S 6 ever, looking back at previous be- Years FromCycleStart havior may show what patterns persist from cycle to cycle. FIGURE23.--Solar cycle amplitude determinations.

Sunspot observations associated with to cycle, several characteristics were Fitting this function to the sunspot the Swiss Federal Observatory in found that were similar. For example, number data for each cycle showed Zurich extend back to the mid-18th the rate at which the sunspot nun> that the function could fit the data to century. Although the early observa- bers increase from the time of sun- within the variations given by the tions are somewhat unreliable, this spot minimum is well represented by daily measurements. It was also data set does provide a long, con- a function that increases as the cube found that the values determined for tinuous record of the number of of the time in months from mini- the parameters for each cycle were sunspots present on the Sun. De- mum. Similarly, the rate at which the well determined within 3 yr of the tailed daily observations of sunspots sunspot numbers decrease from the start of the cycle. Within months of were started at the Greenwich Ob- time of sunspot maximum is well the start of a solar cycle, the starting servatory in 1874. Observations of represented by a function that de- date can be determined. When twing other indicators of solar activity-- creases exponentially with time. A to deternline the amplitude param- such as radio flux, x-ray flux, and single function was devised that eter, it was found that it converges to magnetic flux--were started much combines these two different behav- a constant value within about 3 yr. more recently and only cover four to iors, starting with a function con- This is often before reaching the five solar cycles, at best. While these taining four parameters loosely maximum of the cycle. With both newer data contain much more infor- characterized as: starting time, ampli- parameters detemlined this early in mation about the Sun, the sunspot tude, time from minimum to maxi- the cycle, a prediction can then be number data give a better picture of mum, and ratio of rise time to decay made of how the activity will vary the solar cycle and of cycle-to-cycle time. It was found that the last of over the remaining 5 to 12 yr of the variations. these parameters was unchanged cycle. In figure 23, the anlplitude from cycle to cycle. It was also parameter that is determined at dif- Scientists at MSFC analyzed the found that the time interval from ferent times during each cycle is Zurich data in the form of monthly minimum to maximum is related to compared to its value determined at averages of the daily sunspot num- the amplitude of the cycle. Big cycles the end of the cycle. The ratio of ber counts from 1749 to 1993. Al- reach maximum quickly, while small these two numbers is plotted for though the average cycle is 11 yr in cycles take longer. By employing this each of the last 21 cycles as func- length, individual cycles are any- relationship between rise time and tions of the time from the start of the where from 8 to 15 yr long. In addi- amplitude in the function itself, sci- cycle. For the first eight cycles, the tion, the amplitudes of the cycles entists were left with a function con- sunspot data were less reliable be- vary hy factors of four or more. In taining only" two parameters: starting cause of missing data. These cycles spite of these variations from cycle time and amplitude. are represented by the thin lines. 49 Research and Technology 1993

a00 The Effect of Solar Wind Changes on the 250 Heliospheric Termination Shock 200

150 205-544-7611 !Z. Steven T. Suess/ES52 Several spacecraft are now exploring 100 the outer reaches of the solar system. These include Voyagers 1 and 2, Pioneers 10 and 11, and, presently, 50 Ulysses. New discoveries continue to be made, with the most recent being 0 the detection of the presence of the 1940 1960 1980 1990 2000 1950 1970 boundary between the solar wind Dale and the local interstellar medium-- the heliopause (Gurnett et al. 1993). FIGURE24.--Sunspot numbers, 1940-2000. The heliopause is reported to lie near 120 astronomical units (AU) The later, more reliable data are the earlier cycles. Only the last five from the Sun. Inside the heliopause, represented by the thick lines. This have been plotted so that details are there is a standing shock wave in the shows that if we take the parameters more visible. solar wind that is quasi-spherical and determined early in each cycle, we centered on the Sun. The distance can produce the function that repre- Future research will analyze the to this shock--the "heliospheric sents the final form of that cycle. other available measures of solar termination shock"--is 60 to 100 AU, activity to see if this function works well within the reach of the Voyager as well with them. We also intend to As an added bonus, it was also spacecraft within the next few years. found that the time for the start of search for patterns in the variations Planning for the encounter with the of the parameters to see if future the next cycle is related to the rise termination shock is well under way, cycles can be predicted from the past time of the present cycle. This allows using models of the shape of the cycles. While this research does not the prediction to be extended into shock and how it responds to provide a better understanding of the start of the next cycle. Figure 24 changes in the solar wind. shows the sunspot number data for how the solar cycle works, it does the last five cycles along with the provide a tool for predicting future The solar wind is highly time depen- functions that were fit through the activity and it characterizes the cycle dent, with the dynamic pressure data. Figure 24 also includes predic- in a way that allows for better com- often changing by an order of mag- tions for the activity level for the rest parison with future theories of the of this cycle and the start of the next. solar cycle. nitude over a few days. Over a solar The monthly sunspot numbers are rotation of 27 d, there are quasi- Hathaway, D.H.; Wilson, R.M.; and shown with the thin jagged line. periodic changes in the solar wind Reichmann, E.J. 1993. The Shape Our fit through the data is shown associated with the structure of of the Solar Cycle. Solar Physics, with the thick smooth line. The the corona. Taken together, these in press. goodness of fit between the data changes will drive the termination and our function extends to all of Sponsor: Office of Space Science shock inward and outward over several AU on time scales of days to years.

An analysis of the response of the termination shock distance to solar wind fluctuations has recently been made to understand how the shock

50 Research Programs

motion would affect observations of the shock made during its encounter with a spacecraft (Suess 1993). This 12.8 _ Log(SolarWindDynamicPressure) analysis depends on the speed the shock moves, on the speed of the spacecraft, and on the thickness of the shock. Typical spacecraft speeds are in the vicinity of 5 AU/yr, whereas the shock could reasonably 12.0 be expected to move several AU/mo, so that the shock may move very I ' I I I l quickly in comparison to a space- 5OO craft. There is a great deal of data on the thickness of collisionless shocks, SolarWindSpeed all of which suggests that the shock is very thin by spacecraft standards. That is, given the relative speed of the shock and spacecraft just men- ..I tioned, the shock will pass over the 400 spacecraft in a few minutes.

The conclusion is that thetermination shock is very agile in comparison to I I I I I I I I i I I I I I I I I a spacecraft and would pass over a spacecraft very quickly. This makes 600 ShockSpeed it difficult to base an observation program on first detecting the shock and then adapting experiment proce- dures to conditions in the shock. "_" However, the agility of the shock "5' 200 also provides a way to still construct an observing program that would be able to collect a comprehensive set of information on the shock. The -200 I I I I I I I I I I I I I I reason for this is that solar wind fluctuations occur continuously, 104 driving the shock both inward and outward, with the consequence that once the shock is first encountered

by a spacecraft, it will very likely be 102 encountered several more times. A simple calculation demonstrates this ,c result (fig. 25). The top panel of figure 25 shows synthetic, but repre- sentative data for how the solar wind 100 dynamic pressure changes over a I I I I I I l I I I I I I year's time, along with the solar wind speed in the second panel. 0 100 200 300 Time(d) The third panel shows the resulting shock speed, calculated using a plau- sible set of assumptions. The bottom FIGURE25.--Simulated variation of solar wind and termination panel shows the distance to the shock properties for a period of 1 yr.

51 Research and Technology 1993

termination shock over the same location to another. That is, dynamic shock. The known amplitude of year's time. Overlaid onto this bot- pressure fluctuations in one direction solar wind dynamic pressure fluctua- tom panel are two trajectories for from the Sun are not necessarily the tions leads to the suggestion that spacecraft moving at 5 AU/yr. It is same as in another direction. This is the bumps on the termination seen that both spacecraft would particularly true around solar sunspot shock might have an amplitude of encounter the shock several times. maximum, when solar flares and 10 percent of the total distance to coronal transients are ejecting mass the shock. This is shown schemati- Because shock motion depends on into the solar wind several times a cally in figure 26, which is intended solar wind properties, which are day. Consequently, the shock, which to reinforce the suggestion that the measured on Voyager spacecraft, it might otherwise be quasi-spherical, termination shock is not a smooth will probably also be possible to may be driven outward at one loca- surface. make a definite prediction of the tion at the same time it is being timing for the second and subse- driven inwards elsewhere. This Gumett, D.A.; Kurth,W.S.; Kaiser, ML.; quent termination shock encounters would lead to a bumpy termination Desch, M.D.; and Farrell, W.M. 1993. once the shock is first encountered. The 1992-93 Heliospheric Radio This, then provides a concrete basis Emission Event. Earth Observing for planning an observational pro- System vol. 74, no. 16:241. gram to measure the properties of the termination shock, based on Suess, S.T. 1993. Temporal Variations in knowledge of the solar wind from in J SolarRotationAxis the Termination Shock Distance. situ measurements and timing of the Journal of Geophysical Research first shock encounter. 98:15147-156.

A final point is that fluctuations Sl_nSor: Office of Space Science in the solar wind are only weakly correlated from one

FIGURE26.--Representation of the termination shock for a spatially and temporally varying solar wind. In this case, the shock is continually being bumped outward in quasi-random directions. 52 ResearchPrograms

Understanding the Quiet overlying hot corona. It was not until to be the dominant energy drain on the corona. The importance of this Solar Transition Region m UV telescopes on NASA-sponsored result for the terrestrial atmosphere is The Source of Solar spacecraft began to take observations with improved spatial resolution that that it begins to provide a better Ultraviolet Radiation the inadequacy of describing the understanding of the source of solar transition region as a simple steady- UV radiation. James F. Dowdy, Jr./ES52 state layer began to be seen. Despite 205 -544-7604 the realization by many that small- The UV data being examined were scale, variable processes were play- taken by instruments on the Apollo The quiet Sun is all of the solar ing a role in the basic physics of the Telescope Mount (ATM) on Sk1.,lab in atmosphere that is not showing en- transition region, the notion per- 1973. Data from the Harvard Extreme hanced activity or depressed emis- sisted that these small transient events Ultraviolet Spectroheliometer cov- sion, which is most of the Sun for were simply perturbations on a back- ered the 300 to 1,300 A wavelength most of the time. For a long time, ground steady-state atmosphere. range. Ironically, very little data from this condition was thought to be this wavelength range have been produced by a relatively simple The goal of this research is to take a taken since that time, making these background, steady-state solar atmos- careful, detailed look at the available the latest data available for address- phere. The Sun's transition region is data to establish the importance of ing, in particular, the hotter transition a temperature region between 104 the small-scale, variable component region, which is between l0 t and and 106 K, producing most of the of the quiet solar transition region. It 10(' K. Furthermore, the development solar ultraviolet radiation that im- has been found to be variable every- of data analysis techniques and more pinges on the Earth, providing the where, all of the time, on all mea- powerful computers since the initial main energy input to the upper ter- sured spatial scales and, therefore, analysis of the Skylab data was done, restrial atmosphere and, thereby, cannot be the result of a simple has provided many new ways to get having a major influence on such large-scale, steady-state layer. This a better understanding of the Sun. phenomena as atmospheric ozone. research has also helped to establish that the small-scale, variable struc- Is the quiet solar transition region Most of the Sun's ultraviolet radiation ture in the solar ultraviolet is related variable on small scales? Specifically, comes from the transition region of to the small-scale magnetic field. The does it vary too much to be ex- the quiet Sun, which we know is importance of this result for under- plained by a steady-state model? mostly confined to a layer that is standing the solar atmosphere is that Figure 27 shows examples of the 2,000-km thick. It was tempting to it changes the energy budget for the types of variability that are observed. imagine the transition region as a coronal heating mechanism, one of Feature A is a bright and relatively thin layer with a steep temperature the outstanding problems of solar long-lived event. The event is gradient giving rise to strong heat physics, because the back-heating of 1.7. times brighter in raster 6 than conduction downward from the the steady-state models was thought its mean brightness during a 9-raster

53 Research and Technology 1993

sequence from which these samples are taken. Feature B gives rise to an event of even greater maximum-to- minimum contrast (approximately 2.7) that peaks sharply in time at raster 6. Several high-contrast events can be seen to occur in composite feature C, which is always brighter than average, but bright feature D changes relatively little during the time sequence. Thus, there is no obvious preference for high-contrast events to occur in brighter areas. If instrumental fluctuations are re- moved, then the data still show that the quiet solar transition region var- ies from 10 to 30 percent of the mean intensity in all pixels, with no measurable correlation with intensity. For example, feature E is not usually prominent, yet it achieves high con- trast (approximately 2.1) during two separate brightenings. Such brightenings cannot be explained by a simple steady-state model.

The relationship between the transi- tion region and the small-scale mag- netic field also undermines the notion of a steady, back-heated tran- sition region. Figure 28 shows a grey-scaled image of the transition region at 3.5 X 106 K, with superim-

posed contours of the magnetic field OVI with solid lines indicating positive polarity and dashed lines negative FIOURE27.--Variability of the Ovl 1032 ,_, EUV emission line illustrated by six polarity. The basic unit of magnetic consecutive rasters spanning 33 min (each raster taken 5.5 min structure on the Sun is a loop. A apart). The width of these rasters is approximately 0.08 times the loop shows up on a magnetogram as Sun's diameter. The boxed and labeled features are discussed in a pair of adjacent patches of positive the text. and negative polarity. If ultraviolet emission is produced in such a loop, then a bright feature will be seen on 3,000 to 7,000 km in length. The The analysis of this data has only the boundary between the two adja- spatial variation in brightness and its begun. The Harvard data set includes cent patches of opposite polarity. association with the small-scale mag- spectra correlated with images like Figure 28 shows several such fea- netic field argues against a spatially those shown here. These spectra are tures enclosed in boxes. These fea- homogeneous and steady transition now available, and the analysis soft- tures imply loops that are typically region. ware has been developed to allow a

54 Research Programs

Substorm-Generated Impulsive Plasma Flows

Thomas E. Moore/ES53 205-544-7633

The Dynamics Explorer Retarding Ion Mass Spectrometer (DE-I/RIMS) data set has recently been searched for evidence of impulsive plasma flows expected to accompany substoml collapses of the nightside geomagnetic field. The probability of observing such events is low be- cause their duration is only several minutes per day and the Dynamics Explorer spacecraft spends only a small fraction of its time in locations that are potentially affected. A few examples of these impulsive plasma flows have nevertheless been found, in part because the region of space affected is larger than expected. The nature of the flows observed supports an earlier inference from electric field measurements but indicates that the exact behavior of the magnetic field is quite different from that ex- pected. The results provide addi- tional information about how sub- FIGURE28.--An EUV spectroheliogram of the quiet Sun taken in the Ovl 1032 storms occur and illustrate a new ,_ EUV emission line with contours of the underlying magnetic mechanism for accelerating terrestrial field. The width of this raster is approximately O. 16 times the plasma into the magnetosphere. Sun's diameter. The boxed features are discussed in the text.

The essence of a substoml is the detailed look at the physical pro- Mariska, J.T., and Dowdy, J.F., Jr. 1992. abrupt collapse of the magnetic field cesses occuring at interesting sites Solar Doppler-Shift Measurements in the Ne VII 465 A Emission Line. on the nightside of the Earth from a like those in figures 27 and 28. The Ap. J. 401:754. highly stretched state toward a more most promising aspect of this work nearly dipolar configuration, with an is that it will provide much more Rabin, D., and Dowdy, J.R., Jr. 1992. associated release of potential energy stringent constraints on models of Pervasive Variability in the Quiet stored in the initially stretched field. the quiet solar transition region. Solar Transition Region. Ap.J. Such dipolarization events are gener- 398:665. Dowdy, JR., Jr. 1992. Observational ally accompanied by the detachment Evidence for Hotter Transition of a large volume of the stretched Region Loops Within the Super- Sponsor: Office of Space Science, field region, which is then carried off granular Network. Ap. J. 411:406. Solar Science Branch downstream by the solar wind in the form of an independent magnetic structure called a "plasmoid." Associ- ated with the collapse, the polar aurora brightens and expands poleward dramatically, defining the

55 Research and Technology 1993

expansion phase of the auroral sub- the RIMS instrument. These flows o vii (H+) • VII (He+) +VII (0+) storm. An isolated substorm dipolar- evolved in time or space into cross- *,v.L(H +) •v.L(He +) *v.L(o+) I00 , , , , , , 2400 ization event occurs in 1 to 2 min, winds away from the Earth, along BnT with the auroral expansion continu- the local magnetic field. The varia- ing for a period of up to an hour. tion of the measured velocities 2200 When substorms recur frequently for three ion species is shown in enough that they become difficult figure 30. The time scale over which 130 to distinguish, we speak of a full- the event was observed was approxi- fledged "magnetic storm," which mately 1-2 min, in agreement with produces a characteristic reduction other observations of strong sub- i of the ground-level geomagnetic storm plasma flows, but the motion field, owing to a global-scale current of the spacecraft during the measure- that encircles the Earth, known as ment precludes a purely temporal 0 -10 13h44min46s the "ring current." interpretation. TimeIs) 13h47mJnO6s

Substorm-related flow bursts have A basic theorem of magnetohydrody- FIGURE30.--Plasma flow velocities been found in the DE-I/RIMS data namics (due to H. AlDen) states that during an impulsive set during orbits like that schemati- the plasma along a magnetic field substorm flow event. cally illustrated in figure 29. As DE-1 line must move as a unit with that Also shown is the moved equatorward across field lines field line during the magnetic field magnitude of the that intercept the Earth's surface near changes. The naive expectation, measured magnetic 60 degrees latitude, large headwind based upon the behavior of empiri- field and inferred flows were seen in all ion species cal models of the disturbed geomag- electric field. sampled, exceeding 50 km/s, or netic field (Delcourt et al. 1991), was more than 10 times the speed of the that plasma flows during a collapse spacecraft. The flows were so strong would be inward toward the Earth local magnetic field can be under- that the heavier ion species energies and/or equatorial plane. The change stood to result from centrifugal ef- as seen in the spacecraft frame were of field-line shape would then be fects of the motions driven by the briefly beyond the energy range of as illustrated in the lower half of changing magnetic field. figure 29. The observed flows are in the direction exactly opposite to that These results force a reevaluation of grbil _,, _ Spacecraft and of larger magnitude. The magni- expectations of the geomagnetic field _" _ tude and duration of the flows behavior during substorms. In fact, f _ indicate an outward field-line they corroborate an earlier observa- j/ displacement during the tion of electric fields from which an / _ rv event of approximately / A_ar_tlrue Ba_.._vi_ _ 0.5 Earth radii. The outward substorm motion was in- ferred (Aggson et al. 1977). The '_ observed motion upper half of figure 29 shows how parallel to the field lines could move in a way con- sistent with observations, expanding at high latitudes as they collapse inward at low latitudes. The actual behavior is determined by the global distribution of electrical currents within the plasma medium of the magnetosphere. Motion such as we observe is consistent with magnetic T87Behavior field lines that are in tension owing to a current in the tail, rather than FIGURE29.--Geometry and interpretation of DE observations being inflated by a current system of impulsive substorm plasma flows. within the inner magnetosphere.

56 Research Programs

The results are consistent with the Mass Spectrometer The design process begins with a overall dipolarization of the geomag- Resolution Enhancement digital CAD description of a pro- posed instrument mechanical layout. netic field known to occur during Using an Electrostatic A finite-element mesh is adapted substorms, if the field line shape Lens when stretched is as shown in the to the design, on which Laplace's upper half of figure 29. The intense equation is solved R)r the electric impulsive flows of all species of low- Thomas E. Moore/ES53 potential distribution within the in- 205-544-7633 energy ionospheric ions severely strument. Similarly, the magnetic disturb this high extension of the field intensity and direction are de- ionosphere at the observation points, Modern space plasma ion mass termined and incorporated into a accelerating the ions to many times spectrometry seeks measurement of complete description of the control- their normal thermal energies and the densi W, temperature, and flow ling fields. This permits the calcu- freeing them from gravitational equi- for each ion species sampled, as well lation of trajectories of charged librium. The resulting strong plasma as identification of anisotropies and particles traveling through the device, flows are a significant mechanism for other abnormal features in the spe- usually termed "ray tracing." The accelerating low-energy plasma into cies velocity distributions, under low transmission properties of the pro- Mach number conditions where the low-latitude magnetosphere. posed design can thus be deter- particle arrival directions span the mined, and iterations of the design Aggson, T.L., and Heppner, J.P. 1977. entire sky. To do this at time resolu- can be performed with the objec- Observations of Large Transient tion commensurate with the phe- tive of optimizing itsdesirable Magnetospheric Electric Fields. nomena being observed (often a characteristics. Journal of Geophysical Research fraction of a second) is a feat that 82:5155. essentially requires the simultaneous Electric potentials are generally used operation of an ensemble of identical to select the energy/charge of par- Delcourt, D.C., and Sauvaud, J.A. 1991. instruments, arranged so that their ticles passed through the analyzer to Generation of Energic Proton Shells several fields of view form a fan and a detector. Spaceborne mass analysis During Substorms. Journal of Geo- has, in contrast, been performed by physical Research 96:1585. sweep out the full sky during each spin of a spacecraft. The design of deflection of the particles in a mag- Liu, C.; Perez, J.D.; Moore, T.E.; and a compact and lightweight instru- netic field. Designs capable of re- Chappell, C.R. 1993. Low Energy ment meeting this requirement has solving elements with adjacent mass Particle Signature of Substorm required significant compromise in numbers have been based upon Dipolarization. Geophysical Research specifications for mass resolution, focusing 90-degree deflection mag- Letters, submitted for publication. owing to the impossibility of imple- netic sector geometries using perma- menting conventional magnetic nent magnets (Moore 1977). Such Sponsor: Office of Space Science focusing techniques in such a geom- designs form a sharply resolved mass etry. Through the use of an electro- spectrum by bringing initially diver- static immersion lens, a technique gent particles together along a focal has been developed for achieving plane. Achievement of such focusing sharp mass spectral resolution in this places significant constraints on the design. This technique is being in- overall geometry of an instrument, corporated into an existing design which are incompatible with cluster- for flight on upcoming sounding ing multiple sectors in a cylindrically rocket flights. symmetric arrangement.

57 Research and Technology 1993

In order to overcome this problem, a hybrid design has been adopted AMU=I in which an electrostatic lens is used AMU=4 in conjunction with a simple toroidal AMU= 32 permanent magnet design (in place of a special magnetic geometry) to RegionalPotentiols: achieve the desired convergence of Reg.1: OV initially divergent rays. The design Reg.2:-2,970 V provides for focal length adjustment Reg.3:-2,975 V Reg.4:-2,970 V of the lens by simply varying the n Reg.5:-2,970 V potential applied to one of the lens Reg.6: 0V elements. In contrast, the standard magnetic sector designs must be set for optimal focus by means of mechanical adjustments. Figure 31 shows the analyzer design in a cross- section view. The upper half is an energy/angle analyzer based upon the conventional hemispherical ana- lyzer or "top hat" with a 90-degree deflection (Pollock et al. 1987). The lower half of the analyzer is a toroi- dal yokeless permanent magnet design consisting of wedge-shaped FIGURE31.---Atomic mass units (AMU's) 1,4,32, with no lens, magnetized elements separated by air gaps through which the particles particle ray traces. are deflected (Lynch 1992). The magnetic field is oriented azimuthally around the cylindrical symmetry axis :m AMU=I in a sense so as to deflect positively AMU=4 charged ions radially inward.

Particles within the energy and angular passbands of the hemispheri- cal analyzer are passed on to the 0.6 _-_ RegionalPotentials: magnetic analyzer. Between the exit of the former and the entrance to the I I I I Reg.2:-2,9701: O_ latter, they encounter the new ele- O.4 Reg.3:-2,975 V ment of this design, an electrostatic I Reg.4:-2,985 V immersion lens. In figure 31 the Reg.5: OV Reg.6: 0V immersion lens is absent, and the ion Reg.7: OV rays exhibit significant angular dis- Reg.8: OV persion exiting from the energy ana- Reg.9: 0 V 0.2 lyzer, which grows larger as they traverse the magnetic analyzer, re- suiting in poor separation of the ion species at the detector plane located at the bottom of the figure. 0 I I I ,'%. -0.5 -0.4 -0.3 In figure 32 the immersion lens has -0.2 -0.t been added and activated. The lens In has been biased in such a way that the rays are nearly focused by the FIGURE32.--AMU 1,4,32, with lens, particle ray traces. 58 ResearchPrograms

time they arrive at the detector Application of Focusing Figure 33 shows a computer model plane. The bundle widths for each Electrostatic Mirrors to a cross section of one of seven identi- species are reduced significantly, and cal sectors in the TIDE instrument. Spaceborne Ion Mass this translates into a capability to This figure demonstrates the result separate much more closely spaced Spectrometer of end-to-end computerized elec- masses than in the case without the trostatic ray tracing of ion paths lens. An irreducible (with this de- Craig J. Pollock/ES53 through the TIDE instrument. Such sign) blurring of the bundles remains 205-544-7638 ray tracing was used extensively in because of the finite range of ener- various phases of instrument devel- gies being passed by the energy Several years ago, a report was given opment. Particles enter from the right analyzer. Reduction of this residual on the concept of a focusing electro- within the collimated field of view bundle width could produce even static mirror for use in charged and are selected based on energy greater improvements in mass reso- par-ticle spectrometers in space per charge by the combined action lution, especially at larger masses (Research and Technology 1989.. of the focusing mirror and the RPA. where total deflection, and therefore Annual Report of the Marshall Space The mirror/RPA system rejects par- mass dispersion, are weaker. Flight Center, NASA TM-100369). ticles that are outside a prescribed Such mirrors offer the potential for energy bandpass. More energetic The improvement in mass resolution large apertures and concomitant particles are not reflected toward already realized by this technique is increases in sensitivity in instruments the RPA, but pass through the mirror significant for future instrument de- that have traditionally been charac- and are lost. Less energetic particles signs and well worth the modest terized by small apertures. Large are electrostatically rejected by the added complexity. It will permit ac- enhancements in sensitivity resulting RPA and not permitted to enter the curate analysis of the plasma compo- from the application of this technol- time of flight (TOF) mass analysis sition at very high time resolution ogy will lead to new discoveries chamber below. in situations where the plasma is when instruments using it are de- not cold or dense enough to be ployed into the near-Earth space Since the mirror is not oriented per- monitored with a single aperture, environment. This report describes pendicular to the incoming ion flight conventional mass spectrometer. the application of focusing electro- path, mirror voltages less than the static mirrors, in combination with incoming ion energy per charge are Lynch, K.A. 1992. Fine Structure of Au- retarding potential analyzers (RPA), sufficient to reflect the ion toward roral Particle Acceleration. Disserta- in the MSFC Thermal Ion Dynamics the RPA. For an idealized fiat 45- tion, University of New Hampshire. Durham, NH. Experiment (TIDE), which has been degree orientation, a mirror voltage developed to fly on the Polar space- of 0.5 E/q is sufficient to reflect ions Moore, T.E. 1977. Spectrograph Suitable craft, part of the International Solar toward the RPA. An applied RPA for the Mass and Energy Analysis of Terrestrial Physics Program. A voltage larger than E/q, however, is Space Plasmas Over the Energy unique feature of this combination is sufficient to reject particles from the Range 0.1-10 keV. Review of Scien- the ability to electrostatically control RPA. For this idealized case, then, tific Instrumentation 48:221. the instrument sensitivity, using and for the applied mirror voltage Pollock, C.J. 1987. Rocket-Borne-Low- uplinked instrument commanding or (VM) equal to the applied RPA volt- Energy Ion Measurements in Space. onboard microprocessor algorithms. age (VR=VM), ions are selected in Dissertation, University of New The result is a much more flexible the energy range between VR and Hampshire. Durham, NH. and capable instrument offering a 2VR. As another example, if VM very large sensitivity and an auto- is only 75 percent as large as VR, Sponsor.- Office of Space Science matic gain control (AGC) function (VR=4 VM/3) then, again for the idealized case of a fiat mirror ori- University Involvement: Auburn that provides a large increase in University dynamic range. ented at 45 degrees to the incoming

59 Research and Technology 1993

Mirror

RPA

N Immersi_nLens

I m

Deflector/ UVRejector StartMCP

StartFoil U

StopMCP I 00 2 4 6 In (Y Axis)

FIGURE33.nTIDE flight version particle ray traces. ion flight path, ions are selected in in the MSFC Low Energy Ion Facility of figure 34, the value of VM is fixed the energy range between VR and (LEIF) in 1993. An example of the equal to the value of Vm, A, whereas 1.5 VR. By varying the ratio of the calibration data, illustrating the AGC in the bottom panel, VM is only mirror voltage to the RPA voltage, function of the mirror/RPA system, is 60 percent of VRPA. The effect of the the width of the energy bandpass shown in figure 34. Here, the en- more limited energy bandpass is can be controlled. ergy/angle response of one of the clearly illustrated in this figure. For seven TIDE sectors to an incident the VM=VRp A case, the energy band- We have recently performed exten- 25 eV/q monodirectional ion beam is pass extends from near VRPA=10 V to sive calibration measurements on the shown. The instrument count rate is VRPA=25 V, while for the VM=0.6 VRPA flight version of the TIDE instrument, contoured as a function of sector case, significant transmission doesn't prior to delivery to the Polar space- look direction along the vertical axis occur until VRPA is approximately craft contractor for integration and and the applied VRPA and VM along equal to 17 V and the upper end test. This calibration was performed the horizontal axes. In the top panel of the bandpass remains near 25 V.

60 Research Programs

RPAVoltage 0 5 10 IS 20 25 30 35 40 15 Is,._, ". av...s%_-.'-l;_l o_._:z.N'.. _ I'o". ' •.._U'.-" "" t.5 _ -" " ". :.._ _)_._ ._ 10

o ...

N -lO VM,,/V,,A=10I -15 I k I I _I I I I 0 5 10 15 20 25 30 35 40 Mirror Voltage

RPA Voltage 0 10 20 30 40 50 60 15 I I I I . . I I 0 ... I0

5 • ° -° 0

l_ -10 VMteA/eeA= 0.6 /

-15 J , _ I "1 I i i i 5 I0 15 20 25 30 35 40 Miner Voltage

FIGURE34.--TIDE count rate (Hz).

With careful calibration of instrument spectrometer for flight on a polar the instrument sensitivity on orbit, energy bandpass as a function of orbiting scientific satellite. The through voltage power supply control. both VM and VRPA, which has been increased sensitivity resulting from Thus, an AGC capability has been conducted, the sensitivity of the this technology will result in new achieved that will significantly en- instrument may be reliably and discoveries relevant to the nature of hance the scientific value of the data quantitatively varied by more than the near-Earth plasma environment. returned from the TIDE instrument. 3 orders of magnitude. The mirror/RPA combination used in this spectrometer yields differential Sponsor: Office of Space Science The concept, described previously, energy measurements and allows for of a focusing electrostatic mirror has the ability to quantitatively adjust the been incorporated into an ion mass width of the energy bandpass and

61 Research and Technology 1993

The Ionosphere as an Similarly, because alpha particles evidence concerning the relative Alpha Particle Source make up on average 4.0 percent of contributions of the internal and the solar wind plasma, the presence external sources to magnetospheric of doubly ionized helium (He**) plasma content. Barbara L. Giles/ES53 (alpha particles) in the absence of 205-544-7637 He* has been used as a signature of Recent work investigated RIMS ion ThomasE. Moore/ES53 a solar wind contribution. However, pitch angle measurements with re- 205-544-7633 the application of these indicators is spect to geomagnetic disturbance not straightforward. Magnetospheric level, invariant latitude, magnetic At one time, it was thought that the plasma does contain He** (although local time, and altitude for M/z=2 solar wind was the principal source less than expected from a solar wind ions that are believed to be alpha of the plasma particles populating source) and it contains appreciable particles. Included are outflow the Earth's magnetosphere. However, quantities of He*. Does this suggest events in the auroral zone, polar cap, subsequent studies have confirmed that the magnetosphere is dominated and cusp, separated into altitude the presence of energized ions from by ionospheric ions with a weak regions below and above 3 Earth the Earth's own ionosphere to be mixture of solar wind particles even radii. In addition to a customary present throughout the magneto- when alpha particles are detected? division into beam, conic, and up- sphere. This has turned the debate The ionosphere can generate higher welling distributions, the high-lati- from whether the ionosphere con- charge-state ions, such as He** or tude observations fall into three tributes significantly at all, to a ques- other M/z=2 ions through charge categories corresponding to ion bulk tion of relative contribution. To what exchange interactions through direct speeds that are: (1) less than, (2) degree are the ionospheric and solar ionization by auroral electrons. The comparable to, or (3) faster than that wind sources able to supply the real implication here is that the mere of the spacecraft. This separation, magnetospheric plasma content? presence of He** cannot be consid- along with the altitude partition, ered as an indicator of one source or serves to identify conditions under Because the solar wind and the the other. which these ionospheric source ions thermal plasma escaping from the are gravitationally bound and when ionosphere have the same major The RIMS experiment on the DE-1 they are more energetic and able to compositional element, singly ion- satellite resulted from a major effort escape to the outer magnetosphere. ized hydrogen (H*), it is difficult to to thoroughly characterize the inner unambiguously determine which is magnetosphere's low-energy plasma Figure 35 shows low altitude (_< 3.0 the source of these particles. There component by measuring ions rang- Earth radii) invariant latitude versus is an abundant amount of O ÷in the ing from 0 to 50 eV. The RIMS magnetic local time (MLT) occurrence ionosphere, but little in the solar effort has, in its lifetime, revealed probabilities (2.5 degrees by 1 h wind so that the presence of O ÷ previously unobserved ionospheric bins) for He** field-aligned outflow is viewed as an accepted indicator plasma sources to the magnetosphere, distributions. The scale at the side of of an ionospheric contribution. and provides good observational this plot represents the occurrence

62 Research Programs

12 Two-Dimensional Motion of Oxygen Ions in Earth's High-Latitude Ionosphere

Michael O. Chandler/ES53 205-544-7645

ThomasE. Moore/ES53 >20% 205-544-7633

15% The high-latitude regions of Earth's 10% ionosphere and magnetosphere are 18 sites of interplay between influences S% of the Sun and Earth. This interplay results in veW dynamic behavior of <5% the ions that reside in or traverse these regions. The motions of these ions are studied in detail in an effort to understand where they originated (their source), where they ultimately go to (their sink), and how they affect or are affected by the region through which they travel.

0 MLT Recent studies of the major ion species H ÷, He +, and O* that are FIGURE35.--He ++ field-aligned outflow occurrences. present at high latitudes have shown complex patterns of motion. These probability as a percentage--the Chappell, C.R; Moore, T.E.; and WaRe, motions have revealed new sources J.H., Jr. 1987. The kmosphere as a number of samples fitting the distri- and sinks for these ions and have Fully Adequate Source of Plasma for bution criteria divided by the total the Earth's Magnetosphere. Journal suggested ways in which they may number of samples. These field- of Geophysical Research 92:5896. influence the overall behavior of aligned outflows occur with 10-20 Earth's plasma environment. In percent probability in an oval pattern particular, O* is known to move that covers nearly all local times and Giles, B.L.; Chappell, C.R; Moore, T.E.; Comfort, R.H; and Waite, J.H., Jr. upward from the cusp and auroral appears to be roughly coincident ionosphere in large quantities. In with the auroral oval. There is an 1993. Statistical Survey of Pitch Angle Distributions in Core(0-50 eV) addition, O* has been observed at expansion of this oval to lower lati- Ions from Dynamics Explorer-l: high altitudes over the polar iono- tudes at higher geomagnetic activity Outflow in the Auroral Zone, Polar sphere. Thus it is clear that at least levels and evidence of an increase in Cap, and Cusp. Submitted to the some of the up-flowing O* reaches maximum probabilities. Bulk velocity Jou real of Geophysical Research. escape velocity, with respect to calculations have determined that Earth's gravitational field, and is free these measurements represent out- Moore, T.E. 1991. Origins of Magneto- to traverse the magnetosphere under flows of sufficient velocity to escape spheric Plasma. Review of Geophysics the influence of electric and mag- Earth's gravitational potential. From 1039. netic fields only. However, is it true this, it is suggested that the auroral that all of this outwardly moving O" oval as a whole appears to be a escapes or does some portion--that Sponsor: Office of Space Science consistent source of alpha particles which does not possess escape with sufficient velocity to populate energy--return to the ionosphere? outer magnetosphere regions. If so, where does it return and how does it influence the plasma that already resides there?

63 Research and Technology 1993

FIGURE36.--Two-dimensional 0 + velocity field in the polar ionosphere/magnetosphere.

These questions are being addressed The upward motion is readily appar- escapes the ionosphere and how through the statistical analysis of ent from the dayside cusp/auroral much returns under different geo- more than 4 yr of observations of O ÷ zone (62.5 degrees72.5 degrees the result is beyond the 4,000-km limit set in lite. Although the DE-1 satellite has a poleward transport of O ÷. But no- this study--will show where the ceased operations, the wealth of data tice that as the ions move more escaping O ÷ultimately goes. that it produced is still providing poleward, the velocity turns down- new and exciting information on the ward at the higher altitudes before The goal of this type of research is to behavior of the lowest energy ions becoming predominantly upward on provide a clear understanding of the within the magnetosphere. By statis- the nightside (A <72.5 degrees) in nature of the near-Earth plasma envi- tical analysis it has been possible to what corresponds again to the au- ronment-how it evolves, how it put together a 2-D picture of the roral zone. These downward veloci- interacts with the interplanetary envi- motion of O+ from its sources in ties in the polar cap are indicative of ronment, how it affects the Earth-- the cusp and auroral ionospheres, the ions that were accelerated out of to improve the understanding of the anti-sunward across the polar cap the dayside ionosphere with insuffi- total Earth-space system. The search (fig. 36). The motion of O + along cient energy (or upward speed) to for answers to questions regarding magnetic field lines (the dotted lines escape gravity and, thus, ultimately the fundamental workings of nature in fig. 36) was derived from the RIMS fell back into the ionosphere. The is the heart of scientific inquiry, and data, while the motion perpendicular apparent ballistic trajectories hinted scientific inquiry is an integral part to the magnetic field {which results at by the velocity vectors result from of NASA. from electric fields present in the the horizontal transport of the ions, ionosphere) was taken from aver- under the influence of electric fields, Sponsor: Office of Space Science ages derived by a separate instru- which occurs simultaneously with ment. Combining these two velocity the upward and downward motions. fields gives the average motion in Further analysis of this Wpe can be two dimensions, as shown. used to determine how much O+

64 Research Programs

A Cleft Ion Fountain 1.2 Model 1.0

Dennis L. Galtagher/ES53 205-544-7587 0.0

In recent years, the ionosphere has become recognized as a major source of plasma in the magnet()- sphere (Chappell et al. 1987). The _ 0.4 dominant sources of outflowing z plasma are at high latitudes in the 0.2 auroral zone and in the polar cap. One of these sources has been found in the dayside ionosphere in the 0 vicinity of the northern magnetic cusp and is referred to as the cleft -0.2 I I I I I ion fountain. The cleft ion fountain is -15 -I0 -5 0 5 10 15 estimated to supply over 102t hydro- RelativeCleft InvariantLatitude(degrees) gen and oxygen ions per second, as well as lower fluxes of helium, FIGURE37.--Typical latitude profile of O + flux in the cleft ion fountain. nitrogen, and molecular ions. North magnetic pole is to the right. These ions are thought to be ener- gized perpendicular to the magnetic electric fields. Although a relatively density as a function of position field at a relatively low altitude and clear picture of the properties and over the polar cap. The modeling is then driven outward by the mag- dynamics of cleft ion outflow has based on RIMS measurements of the netic mirror force. At 2 Earth radii, been developed, the global structure, cleft fountain from the DE-lspace- craft and on kinetic simulations of the outflowing ions are found to be interrelationship to other polar cap flowing up magnetic field lines and magnetospheric processes, and outflowing ion trajectories. Although with mass-dependent velocities; the responses to changing geophysi- kinetic simulations could be directly i.e., lighter ions move with greater cal conditions remain to be under- used to predict ion flux as a function upward velocities. As the ions move stood. Due to recent advances in of position, the intensive computa- upward, they are convected anti- imaging instrument design, it has tional requirements make this alter- sunward by an electric field imposed become possible to remotely observe native impractical. on the polar cap by the motion of magnetospheric structures like the A typical latitudinal profile of cleft the solar wind through the Earth's cleft ion fountain on a global scale. oxygen ion outflow is shown in magnetic field. Due to their slower Whether imaging in scattered light figure 37. In this figure, upflowing upward velocities, heavier ions are from the Sun or low-energy neutral oxygen flux is plotted (solid line) convected more strongly anti- atoms, instrument design depends against invariant latitude relative sunward than are the lighter ions. upon estimates of the luminocities to the latitude of the peak in the The resulting anti-sunward "spray," of the source plasmas. flux at about 73 degrees. Flux is or spatial dispersion of ions from the Recent efforts have focused on the normalized to the peak flux of about cleft region of the polar cap, is the 2 X 10 _ per cm'/s. The flux is also originof the name "cleft ion fountain." development of a model of the cleft ion fountain that may be efficiently normalized using a factor of (Ri2) _ to An understanding of the cleft ion used in computer simulations of compensate for the relatively small fountain has developed from a num- global images of this ionospheric variation in spacecraft radial distance ber of point measurements and plasma source. The goal of this (R) during this polar cap pass. Rela- through the computer simulation of modeling is to obtain an analytical, tive latitude is shown increasing ions flowing out of the ionosphere continuous global description of toward the northern pole to the through convective and accelerating outflowing oxygen flux and perhaps right. As shown, the low latitude

65 Research and Technology 1993

boundary of the cleft ion fountain is initial ion energies in order to as- usually sharp, with a more slowly semble an approximate picture of 5 falling profile at high latitudes. The what would be observed in particle dotted line in the figure represents velocity phase space at arbitrary loca- 4 an analytical approximation to the tions over the polar cap. Figure 38 is observed flux profile. an example of the early work in N developing this model of the cleft By using observations from many ion fountain. The figure shows con- orbital passes like that shown in tours of oxygen flux superimposed figure 37, the local time profile of the on the polar wind over the polar cleft ion fountain has been obtained cap, for a source limited in latitude on a statistical basis. On average and 0 and initial energy. Solar magnetic during conditions of low geophysical -2 --1 0 1 2 3 4 coordinates are used in the figure. activity, the cleft ion fountain is ap- X Axis When complete, the modeling of the proximately 2-h wide in magnetic cleft ion fountain will provide an local time and centered at prenoon FtGURE38.--Logarithmic contours of analytical description of fountain local times. For the purpose of this 0 + flux and polar wind. characteristics that can be used to model development, the local time simulate plasma imager observations profile is assumed to be Gaussian becomes possible to relate outflow over the polar cap and, thereby, with a width of 2 h in local time and from a given latitude and at a given contribute to imager design and centered at noon. initial energy to the polar cap loca- mission planning. tions where those outflowing ions Outflowing oxygen trajectories are can be observed. Chappell, C.R.; Moore, T.E.; and WaRe, taken from Lockwood et al. (1983). J.H., Jr. 1987. The Ionosphere as a Fully Adequate Source of Plasma for The trajectories are for a perpendicu- Observed low altitude fluxes, ener- the Earth's Magnetosphere. Journal lar electric field strength of 35 mV/m gies, and densities can be mapped to of Geophysical Research 92:5896- at 90 degrees latitude and no paral- the locations of interest once the 910. lel electric field. In their figure 6, originating ionospheric locations for Lockwood, M.; Chandler, M.O.; Horwitz, oxygen trajectories are shown for various initial energy oxygen ions J.L.; Waite, J.H. Jr.; Moore, T.E.; and initial ionospheric parallel energies are determined. This mapping re- Chappell, C.R. 1985. The Cleft Ion ranging from 1 to 20 eV. Although quires that the influence of the di- Fountain. Journal of Geophysical not strictly correct, these trajectories verging magnetic field, convective Research 90:9736--48. are taken to generally represent the electric potential, and spatial energy paths that oxygen ions would take dispersion of these quantities be Sponsor: Office of Space Science when rotated to the latitude where taken into account. This is performed the outflow occurs. In this way it incrementally over the spectrum of

66 Research Programs

Minor Ion Contributions Ratio(Percentage) to the Ionosphere -1 5 11 17 23 30 36 42 48 54 60 I ...... and Magnetosphere Day Night 90 9O Paul D. Craven/ES53 205-544-7639 6O 60

Reported observations of singly 30 ionized nitrogen (N*) from both °B rockets and satellites have covered 0 the last 30 yr. Measurements in the ionosphere from satellites started in i -30° -30 1958 with Sputnik 3 (Chandra et al. 1970). The reported measurements -6O -60 of N ÷ range in altitude from 140 km to several Earth radii. Most of the -90 -90 early measurements are in the iono- S 4 3 2 1 2 3 S sphere below 1,000 kin. Interest in GeocentricDistance(Re) the ion composition in the outer ionosphere and magnetosphere FIGURE39.--Average N+/O + ratio for all conditions. started with the measurements of O ÷ and He* reported by Shelley et al., in 1972. Subsequent measurements of all of them in some way. The objec- effects. Further out in the magne- ion composition in the magneto- tive is to compare the predictions of totail, the contribution of hea_ T ions sphere resulted in the discovery of computerized physical models that other than oxygen to the total den- low-energy N* and doubly ionized fully simulate the plasmasphere/ sity is something of an unknown. nitrogen (N ÷+)by Chappell et al., in ionosphere with the data to confirm Until relatively recently, few of the 1982. The ambient conditions (i.e., our understanding of ionospheric/ high-altitude (above the topsMe local time, solar activity, geomagnetic plasmaspheric processes and iono- ionosphere) instruments have been activity, and season), over which all sphere/plasmasphere interactions, or capable of separating low energy N* these measurements (covering the determine where the weaknesses and O + and because of this, some of ionosphere and magnetosphere) are. The physical model used is the the O + that has been reported may were made, cover a wide range. The Field Line lnterhemispheric Plasma contain some N*. This study relies reported N ÷number densities range model that contains all the necessaw heavily on measurements made with from a low of 0.001 percent to more ion-neutral and ion-ion interactions, RIMS on the DE-1 satellite. These than 100 percent of the O ÷ number pholochemistry, and diffusion pro- observations were taken from 1981 density. The great range relative to cesses (Richards and Torr 1985). though 1984 and cover altitudes from O ÷is due to the large range in the about 600 km to about 24,250 km. locations and ambient conditions of Relatively little has been done with This instrument is capable of separat- the measurements. N* even though it is the second ing the nitrogen and oxygen ions. most abundant ion in the ionosphere When this study was started, the at the F 2 peak (O ÷ is the most abun- Figure 39 shows a global view of the challenge was to concentrate on and dant), and ionospheric/plasma- ratio of N ÷ to O + as a percentage, in model the plasmaspheric N ÷ and to spheric models show it to be a grey-scale R)rmat, averaged over all compare the model with the mea- constant companion of O ÷. Because seasons, geomagnetic and solar con- surements to determine how well the N* has a mass near that of O*, it ditions, and 12 h in local time. The plasmaspheric processes are under- should follow the O +, but with a dayside and nightside are juxtaposed stood. In order to do this, the major lower density. Its concentration rela- at the center. Dayside local time is ions (those with the highest density, tive to O* can be used as a test of on the left and night on the right. H*, He +, and O +) had to be included the importance of transport relative The geocentric altitudes run to the because ionic nitrogen interacts with to chemical production and loss left and right from the center.

67 Research and Technology 1993

Dipole field lines centered on the The studies will also indicate how The Tethered Satellite Earth and corresponding to McIlwain well we understand the physical System-1 Research on L values of 2 to 11 are shown as the processes that govern the interac- Orbital Plasma solid lines with those for 2 to 5 la- tions between different regions of beled. The darkest grey scale repre- Earth-space, in particular the thermo- Electrodynamics sents ratios that are greater than or sphere, ionosphere, and magneto- Investigation equal to 60 percent, while the white sphere. An understanding of these areas represent no data. One of the regions and the processes that take Nobie H. Stone/ES53 most apparent features in this plot is place in them, particularly the 205-544-7642 the fact that on the dayside, the ratio interactions between different is largest between geomagnetic constituents and the connections In 1985, the MSFC Research on field lines that represent the outer between different regions, is an Orbital Plasma Electrodynamics plasmasphere and the equatorward important part of understanding the (ROPE) investigation was selected side of the auroral zone. On the Earth's total environment and for the first TSS mission. ROPE flew nightside, the ratio is greatest in changes to it. on TSS-1 in August 1992 (Stone the southern hemisphere in the 1992, and Dobrowolny and Stone equatorward region of the outer Chandra, S.; Troy, B.E.; Donety, J.L., Jr.; 1993). The investigation consisted plasmasphere. The nightside auroral and Bourdeux, R.E 1970. OGO 4 of two banks of instruments to mea- zone field lines (the outermost of the Observations of lon Composition sure the characteristics and distribu- field lines shown) have a reduced and Temperatures in the Topside tions of charged particles around the Ionosphere. NASA/Goddard Space amount of N* relative to the day side. tethered Italian Space Agency-built The data in this figure indicate that Flight Center Document No. X4515- 70-1. satellite--one bank mounted on the the ratio is generally greater than 30 satellite's surface and the other on percent in the regions just men- Chappell, C.R.; Olsen, R.C.; Green, J.L.; the end of the satellite's fixed boom tioned. In the inner plasmasphere Johnson, J.F.E.; and Waite, J.H., Jr. (Stone et al. 1993). Three Soft Par- 1982. The Discovery of Nitrogen the ratio is roughly 10 to 30 percent, ticle Energy Spectrometers (SPES) Ions in the Earth's Magnetosphere. with a peak around 2 Re geocentric were mounted on the satellite's sur- distance on the night side between Geophysical Research Letters 9:937. face-one at the equator, one at +60 degrees geomagnetic latitude. Richards, P.G., and Torr, D.G. 1985. 45 degrees, and one on the spin Seasonal, Diurnal, and Solar Cyclical axis. It was intended that these Overall it is shown that, on average, Variations of the Limiting H + Flux in body-mounted sensors, in conjunc- N* is present practically everywhere the Earth's Topside Ionosphere. tion with satellite spin, map the in the magnetosphere and, in Journal of Geophysical Research distribution of electron flux to 91:5261. general, its density is a significant the satellite's surface. The boom- fraction of the O ÷ density. Studies Shelly, E.G., Johnson, R.G., and Sharp, mounted sensor package consisted presently in progress that compare R.D. 1972. Satellite Observations of of two SPES---one facing the satellite the measurements with the physical Energetic Heavy Ions During a and the other facing radially away-- model will indicate how well we Geomagnetic Storm. Journal of and one Differential Ion Flux Probe understand all the processes that Geophysical Research 77:6104. (DIFP) facing the satellite (fig. 40). affect the terrestrial ions including The purpose of the boom-mounted their production, loss, and transport. Sponsor: Office of Space Science sensors was to measure the ion and electron flux into and out of the plasma sheath surrounding the satellite.

68 Research Programs

The objective of the ROPE investiga- affected by the geomagnetic field, the potential of the boom-mounted tion was to study the complex phe- and the magnitude of such a current sensor package, exhibited a minor nomena and processes expected as a function of the ambient iono- problem in its low-potential range. to exist around a satellite traveling spheric parameters and the magni- This problem, which resulted from a at mesothermal speeds (supersonic tude of the w)ltage developed across mismatch between the measurement with respect to the ions and neutrals, the tether. The ionization of neutral and commanding rates in the feed- but highly subsonic for electrons), gas within the sheath and the effect back loop, is easily corrected. of ionization on the tether current that is highly biased and extracts In addition, the data obtained by electrons from the ionospheric could also be investigated. ROPE indicate several interesting plasma. For example, it was ex- events in the behavior of the tether pected that for tether lengths greater The prime ROPE objectives could at low voltages and short deploy- than 10 km, the satellite would be- not be met because the system de- ments. For example, it was deter- come biased to a potential of several ployed to only 256 m, rather than mined that the charge carriers for the kilovolts. In this case, measurements the planned 20 km. However, in tether current are suprathermal elec- from the ROPE sensors would pro- spite of this, the ROPE investigation trons in the 40 to 50 eV energy vide a unique opportunity to investi- had several accomplishments and range--not the thermal electrons gate the resulting high-voltage will contribute to the understanding (0.1 eV range) as had been expected. plasma sheath, the way in which of the physics of short electrody- current would flow through the namic tethers in space. This conclusion was arrived at from sheath to the satellite, two approaches. First, the flux den- how this current would The instrument design and its opera- sity of the suprathermal electrons be distributed and tion and control were validated. The detected by the SPES-3 sensor on SPES-5 two types of sensors, DIFP and SPES, the surface of the satellite (fig. 41(a)) both performed as expected. The was integrated over the area of SPES-4 floating supply, which controls the satellite's surface to arrive at a total electron flux to the satellite (Winningham et a]. 1992). If these FixedBoom electrons were the charge carriers, the total electron flux sh()uld be in 45° accord with the measured tether current. This was found to be the case. Secondly, these data represent SPES-2 an event where the satellite poten- SPE$-3 tial increased over a period of time (fig. 41(c)). As the satellite's poten- S-Band tial increased, the energy and current Antenna ROPEBoom-Mounted density of the thermal electr(ms als() SensorPackage increased (fig. 41(b)). If these elec- i trons were the current carriers, the total tether current shoukl have also i increased--but the current did not TSS-1 Satellite respond to the increased thermal electron flux and, in fact, decreased FIGURE40.--ROPE sensor location. slightly. This is interpreted to mean

69 Research and Technology 1993

ionization and charge-transport processes that could account for suprathermal electronics, created at the orbiter, being observed at the satellite 256 m away.

Dobrowolny, M., and Stone, N.H. 1993. A Technical Overview of TSS-1: The First Tethered Satellite System Mission. In press, Nuovo Cirnento.

Stone, N.H. 1992. An Early Assessment of the TSS-1 Mission. Invited paper, EOS Transactions, American Geophysical Union (AGU) 73 (42), 424.

Stone, N.H.; Wright, K.H., Jr.; Winningham, J.D.; Biard, J.; and Gurgiolo, C. 1993. A Technical Description of the TSS-1 ROPE Investigation. In press, Nuovo Cimento.

Winningham, J.D.; Baird, J.; Stone, N.H.; ,,_qcl 0.00_ and Wright, K.H., Jr. Tethered 1992/218:02 19:01 19:46 20:31 21:16 22:01 22:46 23:31 Satellite Current Collection System-- How Well Do We Understand It? EOS Transactions, AGU 73 (42), 422. FIGURE41 .--(a} Suprathermal particles measured by SPES-3, (b) thermal particles measured by SPES-3, (c) satellite potential, Wright, K.H., Jr.; Stone, N.H.; and (d) tether current. Winningham, J.D.; and Samir, U. 1992. Preliminary Observations of that the bulk of the current is carried correct, it will carry some interesting the ROPE Experiment During the by the suprathermal electrons (fig. implications. For example, thermal First Tethered Satellite Mission. EOS 41(a)), and that the slight increase in electrons exist in the natural geo- Transactions, AGU 73 (42), 424. flux due to the enhanced number of plasma environment. But the 40 to thermal electrons being collected 50 eV electrons do not. They must Sponsor: Office of Space Science was insignificant (Wright et al. 1992). be created somewhere, and the best theory is that the orbiter, with its University Involvement: University If the conclusion that the current is cloud of water and other gaseous of Alabama in Huntsville carried by suprathermal electrons emissions, is involved. The next step rather than thermal electrons is will be to identify the appropriate

7O Research Programs

Application of Automated Functiou FilamentCurrent El.Repeller AcceleratorBias Data Acquisition to the N-n N--n N-n Low-Energy Ion Facility AdjustFilament 4- 12o- I 120- 90- Victoria N. Coffey/ES53 2 60-90- 60- 205-544-7635 150-30- _ O-l- aoo- 0- The MSFC Magnetospheric Physics ExtradorRate ShieldPlate UpperMu LowerMu Branch laboratory focuses on the development and testing of low- N--n N--n N--a N--n energy ion mass spectrometers and " ,so-; so- electron detectors. The new genera- CurrentReadFrom 1_o-I 12o-I 90 - 90- 90- tion of detectors requires large FaradayCup 60 - 60- 60- w)lumes of data-taking, which led toward the efforts of automating the i-;l testing and data-collecting sequences. This report describes the application 1E-9 of the automated laboratory toward a !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! recent intense test and calibration 1E-10 that was done for the TIDE to be !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!___!!!!!!!!!! flown for the Global Geospace Sci- ence (GGS) Mission. 1E-11

The automation of the LEIF is based 1E-12 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! on a Macintosh IIfx TM multi-tasking

computer and the LabView TM soft- 1E-13 ware and hardware from National !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!_!!!!!!!!!!!!____!!!!!!!!!!!!____!!!!!!!!!!!_!_!_!!!!! Instrument. This software is a graphi- cal, object-oriented language that ...... 1E-14 allows the development of a virtual instrument (VI) that can define a ...... 1E-15 measurement of an instrument or emulate an instrument. These VI's, in turn, can become a subprocess to a larger VI or procedure. FIOURF42.--Ion source front panel.

There are several types of instrument The interfaces used were eighter small voltage changes to the source devices and controllers in the digital, analog, or the general pur- elements. After interfacing LabView TM LEIF lab to be interfaced with the pose interface bus (GPIB). and the computer with the power

LabView TM software and hardware supplies, the particle beams were for the basic "handshaking" require- For example, the ion source in the easier and quicker to obtain with ment. VI's were developed to control laboratory is controlled by 12 sepa- small controlled voltage changes the 12-ion-source power supplies, rate power supplies that are used to (40 mV). As shown in figure 42, the the motion of the two-axis instru- optimize the particle beam. Manu- controls of the ion source are listed ment fixture, the motion of a Faraday ally, it was not easy to tune the across the top on the front panel. To cup, an electrometer that measures source for a particulate beam energy obtain a desired particle energy, the the current from the Faraday cup, a and was time consuming to obtain filament current is slowly brought up pulse height analyzer, a chamber low-energy particle beams due to the to the nominal value. Then the non- pressure controller, and so forth. sensitivity of the source to even varying power supplies are set to 71 Research and Technology 1993

their values: an electron repeller, the that have to be typed in by the user Do i= Minimum azimuth angle, anode potential, and the five mag- before starting the program. The maximum azimuth angle netic coils (not shown in the figure). right side of the front panel shows 1. Move rotation axis to next The shield plate, extractor plate, and the output data parameters that are upper and lower mu metals are then being obtained in real time from the angle input. slowly swept while watching the different devices during the test. The 2. Write angle to computer output of the electrometer measuring bottom figure contains the inner screen and to file. the current from the Faraday cup. loop of the VI. The script to this VI The current to the Faraday cup is is listed below: Do i= Minimum polar angle, maxi- plotted as a function of time to view mum polar angle the response of the beam to the Do i= 1, Number of data uploads 1. Move rotation axis to next settings. to instrument angle input. After the basic handshaking VI's 1. Move Faraday cup into 2. Write current angle to com- were developed, they could be built beam path, read electrome- puter screen and to file. into larger VI's that make up control- ter, move out cup, write electrometer current to com- and-data-taking sequences. A front 3. Move Faraday cup into panel and partial code of a VI that puter screen and to file. beam path, command power was used to test TIDE is shown in supply sweep for retarding 2. Read particle energy of ion figure 43. The left side of the front source and write to file. potential curve, plot to panel shows the control parameters screen, and then print.

InputControls PresentValues 4. Inquire over Ethernet line to a UNIX machine to verify status of data upload to FileName instument. BeamEnergy enddo [I 04102346.dntII 101 2s.ol enddo enddo PCTimeStomp

II43s14:s6:o3II The development of this automated system has resulted in significant NumberofTransferControls BeamEnergy increases in the efficiency and value of the LEIF laboratory. It would not have been possible to meet the strin- gent requirements of the TIDE test- FaradayCupCurrent ing and calibration without the use of this automation system for such MinimumliltAngle MinimumRotateAngle lengthy tests. It has proven to be TransferControlCounter versatile for new applications, and procedures are easy to implement with the hardware boards and the MaximumTiltAngle MaximumRotateAngle 1iltAngle modular, icon-based software. In the future, more work will be done on completely automating the ion NumberofSteps NumberofSteps RotateAnqle source. inliltSweep inRotateSweep

Sponsor.- Marshall Space Flight Center Director's Discretionary Fund

FIGURE43.--Ion source front panel of VI.

72 Research Programs

Enhanced Capabilities of there have been many efforts to simulation and miniaturization tech- an Electrostatic Deflection design scientific instrumentation nology and the future applicati(m of capable of characterizing the lower these improvements to a nev,,' genera- and Collimation System ionosphere ion plasma. In that re- tion of space instruments. gard, the Differential Ion Flux (DIF) Nelson G. Martinez/ES53 Probe (Stone et al. 1985) has proven The main feature of the EDCS is an 205-544-7653 to be highly successful after having electro-optical system consisting of been flown on two sounding rocket a set of 45-degree beveled slits. Each The description of the lower iono- and three space shuttle missions. side of the slits becomes an elec- sphere populations of multiple ion One of the most important reasons trode with a shape of an inverted plasma streams differing in flow for this achievement is the design isosceles triangle, being plated thor- direction is fundamental to the un- of an Electrostatic Deflection and oughly with copper and with the derstanding of the mechanisms of Collimation System (EDCS) as part two slanted sides electrically insu- the ionosphere/atmosphere cou- of the DIF sensor head. This article lated from each other. Each of these pling. After the launching of the first briefly describes modifications to the sides has an applied voltage swept artificial satellite in the late 1950's, EDCS design by using ray tracing through a range from 0 to _+15 V,

t 0.133 1.197 3.4mm 30.4mm

i \\ I I I I I Slits I ToRPAandEledronics

)

) :I i N 000-120x 0.125Unf.Screw

Scale12:1

FIGURE44.--Cross sections of EDCS on DIF.

73 Research and Technology 1993

properties, by cutting the profile using a specially designed mill PartideEnergy:6.300eV cutter. The electrodes' external conducting surfaces are made 1.5 EntryAngles:Iheia= 90 by vacuum deposition. Phi= 90 The modified EDCS will be integrated RegionalPotentials: into the prototype of the Cometary Reg.1: OV Rendezvous Ion Mass Spectrometer Reg.2: OV (CRIMS) instrument. This instru- . 1.0 Reg.3: 0 V Reg.4: 0 V ment has been thoroughly tested J Reg.5: OV in the Low Energy Ion Facility; con- Reg.6: 0 V sequently, the results of testing Reg.l: 0 V Reg.8: 0 V the modified version can be fully Reg.9: 0 V assessed by comparison with the 0.5 Reg.10: OV existing data. The CRIMS modifica- Reg.11: IOV Reg.12: -IOV tion is shown in figure 45. Five sets Reg.13: IOV of slits, each flanked by a set of Reg.14:-10 V electrodes, make up the new instru- Reg.15: lOV Reg.16: -IOV ment aperture. Each slit is 3.4 by 0 Reg.17: OV 44.5 mm, providing a total aperture 0 03 1.0 1.5 area of 7.5 cm 2. The electrode set Inches covers the 3.4 mm interslit space and is permanently fastened to the FIGURE45.--CRIMS deflectors particle ray tracers. aluminum substrate. The bias voltage is supplied via two buses with respectively, in a 400-ms period. The shape, as in the DIF, to a much spring contacts running along the electrodes' lateral sides. interelectrode electric field makes it better performance with electrodes possible to increase the polar angle of pentagonal contour. The simula- Space plasma instrumentation fitted resolution from 5 degrees with tions lead to semicircular electrodes with the larger apertures permitted simple slits, to about 60 degrees, with a radial electric field configura- by the new electrode design will allowing the increase of sensitivity tion and eventually to the cross allow a better description of the distinctive to the DIF probe. sections shown in figure 44. densely populated multiple plasma ions streams typical in the lower The application of a computer Although the electrode cross section terrestrial ionosphere. simulation using a 2-D ray tracing seems relatively simple, the design program was the first step needed requires highly miniaturized com- Stone, N.H.; Leveler, B.J.; Chisholm, W.L; to improve the EDCS. The perfor- ponents that must be capable of and Wright, K.H. October 1985. Instrument for Differential Ion Flux mance of several electrode cross withstanding the severe launch envi- Vector Measurements on Spacelab 2. sections was computer simulated. ronment typical of the sounding Review of Scientific Instrumentation The results range from poor sensitiv- rockets payloads. The electrodes 56(10). ity with electrodes consisting of two shown in figure 44 are constructed Sponsor: Office of Space Science parallel plates, to a better sensitivity from Noryl TM, a commercially avail- by using plates with the triangular able plastic with good machining

74 Research Programs

Infrared Spectroscopy of 4 the Earth's Upper C2H7 Atmosphere and (_N2 Planetary Atmospheres

____ '_ 3 Mion M. Abbas/ES55 H(N 205-544-7680 _ HC3N

Infrared thermal emission observa- ._ 2 tions from ground-based, airborne, I and spacecraft platforms provide a powerful tool for studies of the w C3H4 thermal structure and constituent i distributions of the atmospheres of _ 1 the Earth and the planets. Many " atmospheric gases exhibit vibra- tional-rotational transitions in the 10-3,000 cm -1 spectral region, which may be observed with high sensitiv- 0 i I 200 400 600 800 ity and high spectral resolution spec- 0 trometers. The observed spectrum of Wave Number(cm-I) the Earth's atmosphere, for example, includes spectral features of the trace FtGURE46.--Titan synthetic limb tangent spectrum Av=0.5 cm -1 .

gases CO2, H20, HO v H202, OH, N20, NO, NO a, HNO 3, N20 s, CIO, infrared observations with instruments the Vol,ager data. These calculations CIONO2, HF, HC1, and HCN. A syn- with a finite field of view. An analy- provide a basis for comparison with thetic infrared spectrum of Saturn's sis of a large amount of data ob- the Kuiper Airborne Observatory moon Titan, calculated for a model tained from spacecraft measurements (KAO) observations of the two atmosphere with a limb tangent becomes a very time-consuming sources in order to develop infrared viewing geometry, exhibits some process when the instrumental and photometric standards for in-flight very prominent features of a number physical processes in the atmosphere calibration of the Infrared Space of trace gases in Titan's atmosphere are fully accounted for in order to Observatory (ISO) Photopolarimeter (fig. 46). A detailed analysis of the minimize the retrieval errors. Instrument (ISOPHOT). KAO flux observed infrared spectra provides observations of Uranus and Neptune information about the temperature The second focus area was develop- made on March 7, March 16, and and gas concentration profiles, and ment of infrared radiative transfer July 17, 1992, are found to be in physical and chemical processes in models and inversion techniques for agreement with the model flux calcu- the atmospheres. studies of Saturn and Titan, in sup- lations to within the uncertainty in port of the Composite Infrared Spec- the model temperature profiles. Infrared radiative transfer models trometer (CIRS) on the Cassini and spectral inversion techniques for orbiter mission. Preliminary studies Sponsors: Office of Space Science studies of the thermal structure and of radiative transfer models and and Marshall Space Flight Center constituent distributions of the Earth suitable methods for analysis of syn- Director's Discretionary Fund and planetary atmospheres have thetic data generated for the two been developed at MSFC. The three sources to be observed with the CIRS main focus areas concentrated on instrument are in progress. during 1992 are described in this article. Thirdly, radiative transfer models have been developed for calculation The first focus area was development of planetary-averaged broadband of rapid inversion techniques for thermal emission flux of Uranus and accurate retrieval of thermal structure Neptune, with the atmospheric tem- and gas concentration profiles from perature profiles determined from 75 Research and Technology 1993

Imaging the Auroral Oval at Vacuum Ultraviolet Wavelengths

Jerry K. Owens/ES55 205-544-7678

The emissions of light known as auroras result from the collisions between energetic particles (such as protons and electrons) and atmos- pheric gases in the lower thermo- sphere (altitudes between approxi- mately 100 and 150 km). These are solar wind particles that are swept up by the Earth's magnetic field and accelerated by the various electro- magnetic processes operative within the magnetosphere. Large fluxes of these particles (equivalent to 100-million kW during the almost daily events known as magnetic substorms) are channeled down into the atmosphere at high latitudes. The auroras occur around a magnetic FIOURE47.--The UVI in a clean room in the Space Science Laboratory. field line footprint corresponding roughly to a geomagnetic latitude of 70 degrees, but are displaced to This orbit will allow the UVI to view different regions of the magneto- lower latitudes at local midnight. the entire auroral oval for approxi- sphere, the UVI will also provide a The band of emissions thus formed mately 9 h per orbit, and it will be frame of reference that will allow around the geomagnetic poles is able to perform studies at higher auroral features to be related to known as the auroral oval. The ener- spatial resolution of smaller regions events monitored in remote regions getic particle collisions produce for the remaining 9 h. Operating in of the Earth's magnetosphere. emissions throughout the spectrum the vacuum ultraviolet, UVI can from the vacuum ultraviolet to the provide information on both the The UVI comprises a fast optical infrared but, to date, almost all of sunlit and dark auroras, vastly in- system (f/2.8) with good image qual- the work has been done in the vis- creasing the scope and value of the ity over its full 8-degree field of ible wavelengths observable from data for global studies that are now view, a passively cooled intensified the ground. The observations have needed. Using images from UVI CCD focal plane detector that repre- also been restricted to nightside acquired in different spectral bands, sents an evolution of systems devel- aurora due to the severe limitations researchers will be able to determine oped by this research group for imposed by the bright scattered sun- the characteristic energy of the par- other programs, and a set of narrow light on the dayside of the Earth. ticles incident on the atmosphere as bandpass interference filters. To well as the total energy deposited make quantitative measurements in The Ultraviolet Imager (UVI) (fig. 47) (Germany et al. 1990). Since the the 120- to 220-nm wavelength re- was constructed and delivered in instrument is an imager, the spatial gion, new filters had to be devel- July 1993 for integration as part of the and temporal morphology of the oped (Zukic et al. 1990a and 1990b) Polar spacecraft of the GGS program. aurora will also be studied. Since with bandpasses as narrow as 5 nm The Polar spacecraft is scheduled to images of the auroral oval obtained (fig. 48), which is a major advance in be launched in 1994 into a highly from space provide spatial/temporal filter technology over previously eccentric orbit (9 × 2 Earth radii). information that maps back to attainable bandpasses in this spectral

76 Research Programs

1356 emission spectrum of the meso- 0.35 Spectroscopy of the Mesosphere and sphere, thermosphere, and iono- 0.30 sphere under both sunlit and dark Thermosphere From conditions over a broad wavelength 0.25 the Space Shuttle range (30 to 830 nm). 0.20

0.15 Jerry K. Owens/ES55 The ISO is an array of five state-of- 205-544-7678 0.10 the-an imaging spectrometers, each of which has an intensified CCD 0.05 Spectroscopy is a powerful means focal plane detector that allows for remote sensing of the composi- 0 10's of nm of spectral information 1,200 1,400 1,600 1,800 2,000 tion and temperature of the atmos- to be acquired simultaneously, while Wavelength phere, and these measurements acquiring spatial information along allow a determination of the physical the length of the spectrometers' slits. and chemical processes occurring in As a result, ISO was able to measure FIGURE48.--An example of the the region of the atmosphere being emissions from almost all the species wavelength response of observed. The mesosphere (about of interest in mesosphere and a narrow bandpass 60 to 100 km) and thermosphere vacuum ultraviolet filter thermosphere. (100 km to approximately 500 km) developed for the UVI. are regions that have extensive emis- Among the most interesting and sion spectra in the UV, visible, and important topics in the study of region. Thus, UVI represents techno- NIR spectral regions. Much of the the MLT region is the chemistry of logical advances in the state of the spectroscopy of this region of the ozone. The production of ozone in art in optics, detectors, and vacuum atmosphere has been done from the the mesosphere is the result of a ultraviolet filters. ground, where it is limited to night- chemical reaction inw_lving atomic time observations of visible wave- oxygen, molecular oxygen, and a Germany, G.A.; Torr, M.R.; Richards, lengths, or by small instruments third body resulting in the creation P.G.; and Torr, D.G. 1990. The flown on sounding rockets or satel- of ozone and leaving the third body Dependence of Mode|ed Ol 1356 lites, which have covered limited unchanged. Thus, the concentrations and N 2 Lyman Birge Hopfield Au- portions of the wavelength range at roral Emissions on the Neutral Atmo- of atomic and molecular oxygen any one time. The mesosphere/lower must be determined, which makes sphere. Journal of Geoph)_ical thermosphere (MLT) region (about the study of oxygen emissions and Research 95:7725. 60 to 150 km) is too low for direct chemistry necessary. Owens et al. measurements from satellites and Zukic, M., Torr, D.G.; Spann, J.F.; and (1993) have begun a study of these too high to use high-altitude aircraft emissions and the associated chemis- Torr, M.R. 1990a. Vacuum Ultraviolet or balloons. Measurements of this Thin Films. 1: Optical Constants of try using data obtained by ISO on region have, until now, been limited the ATLAS--1 mission. The dominant BaF 2 , CaF., , LaF_, MgF, , AI_,O_, to occasional sounding rocket flights. destruction mechanism for ozone in HfO e , and SiO e Thin Films. Applied Thus, the term "ignorosphere" has Optics 29:4284. often been used in connection with the mesosphere is chemical reac- tion with atomic hydrogen, which this region. Remote sensing tech- Zukic, M.D.; Torr, D.G.; Spann, J.F.; and produces molecular oxygen and niques are now being developed Torr, MR. 1990b. Vacuum Ultravio- vibrationally excited hydroxyl radi- for the study of the MLT region. let Thin Films. 2: Vacuum Ultraviolet cals. Destruction of hydroxyl then All-Dielectric Narrowband Filters. The Imaging Spectrometric Observa- occurs by reaction with atomic oxy- Applied Optics 29:4293. tory (ISO) flew on the first mission gen to form molecular oxygen and of the Atmospheric Laboratory for atomic hydrogen, so there is a natu- Sponsor: Office of Space Science Applications and Science (ATLAS,-1). rally occurring catalytic destruction This was a Spacelab mission that of ozone by atomic hydrogen. As was launched on March 24, 1992, shown in figure 49, ISO measured and landed April 2, 1992. From the hydroxyl (OH) at night, as well as space shuttle, the ISO was able to the oxygen emissions needed to measure, for the first time, the study oxwgen chemistry.

77 Research and Technology 1993

Because of its importance in the 2O destruction of ozone, it is also very (7-1} (6-1)(8-2) (5-1) {7-2) {6-2} (5-2) (7-3}{4-2)(6-3) (S-3) (7-4) desirable to measure hydroxyl in the •_ 15 daytime. However, bright dayglow I emissions, such as the first positive system of molecular nitrogen, ob- " S scure the hydroxyl emissions seen at night. ISO made the first measure- 0 2,600 2,700 2,800 2,900 3,000 ments from orbit of electronically Wavebngth (A) excited hydroxyl in the dayglow SO (Morgan et al. 1993), which emits (6-4)(3-3) (4-4)(3.-4) (4-5) (3-5) (2-5) {3-6} (4-7) (54) (4-0) light of wavelengths around 309 nm. 4O ' ' '(5-4).... '(6-7}"(s-7) This unique measurement of the 0z HzbI ,(s-i) (6-2) {5-2} (4-2) (5-3) 3O i i , -- altitude profile of hydroxyl in the dayglow required very careful de- sign, construction, and execution of Clg 10 the instrument, the observation tech- 0 nique, and the analysis technique to 3,000 3,200 3,400 3,600 3,800 4,000 extract this weak emission from the Wavelength(l) bright scattered-light background of 1,000 the dayglow. Oi _, z r,_7 Ih[.O_tlm(O-O) 8OO OI Another electronically excited mo- ._ 600 lecular emission resulting primarily Pq_ t Q r'2 from resonance fluorescence scatter- '0' ',e', D ing of sunlight is the first negative 20O ' g,lllldtllLl system of ionized molecular nitro- , L_ ,L.....,1.,,,,,._ m:41 Jm t. .,j 0 gen. The peak concentration of ion- 4,000 5,000 6,000 7,000 8,000 9,000 ized molecular nitrogen is in the Waveleqth (A) thermosphere at an altitude of about 160 km. The photochemical scheme FIGURE49.--Spectrum of mesospheric nightglow over New Guinea measured for this species has been the subject by the ISO on ATLAS-1 at about GMT 18:05 on day 88, 1992, of much debate over the past de- at an altitude of approximately 80 km. cade, and a test of the model has been problematic due to the intense Morgan, M.F.; Ton., D.G.; and Torr, M.R. Taken by the ISO Spectral Spatial scattered sunlight background 1993. Preliminary Measurements of lmager on ATLAS-1. Geophysical against which the measurements Mesospheric OH X2II by ISO on Research Letters 20:515-18. must be made. Since a determination ATLAS-1. Geophysical Research of the relative populations of vibra- Letters 20:511-14. Torr, M.R.; Ton., D.G.; Chang, T.; tional levels higher than two require Richards, P.G.; Baldridge, T.W.; information on vibrational progres- Owens, JK.; Dougani, H.; Fellows, C.; sions that cannot be observed from Owens, J.K.; Ton', D.G.; Ton', M.R.; Swift, W.; Yung, S.; and Hladky, J. Chang, T.; Fennelly, J.A.; Richards, the ground, the high-quality mea- 1993. The First Negative Bands of P.G.; Morgan, M.F.; Baldridge, T.W.; surements made by ISO on the Na÷in the Dayglow from the ATLAS- Fellows, C.W.; Dougani, H.; Swift, ATLAS-1 mission (Torr et al. 1993) 1 Shuttle Mission. Geophysical W.; Tejada, A.; Orme, T.; Germany, Research Letters 20:523-26. provide the first information on this G.A.; and Yung, S. 1993. Meso- issue. spheric Nightglow Spectral Survey Sponsor: Office of Space Science

78 Research Programs Astrophysics III I II

Burst and Transient 12 TriggerNo.160 TriggerNo.404 Source Experiment Observations of Gamma-Ray Bursts - 8 x x Gerald J. Fishman/ES66 205-544-7691

In spite of two decades of study, the :4 4- origin of gamma-ray bursts remains I 1 I I I I I I I I I 1 I A I i I I I I I I an enigma. The bursts last from a 0 4 8 12 16 2O -10 0 I0 20 30 4O few milliseconds to several hundred $ s seconds, often exhibiting complex temporal structure on many time- 20 scales. Their spectra are nonthermal, TriggerNo.761 TriggerNo.109 with almost all of the luminosity in the low-energy gamma-ray band. No 20 unambiguous counterparts have been found at any other wavelength. Some gamma-ray burst emission has been seen at photon energies above x IS 2 GeV. _.12 g-

The Burst and Transient Source Experiment was designed primarily 8- I0 to investigate gamma-ray bursts, with J i i I I I I i i i t t t unprecedented sensitivity. BATSE is -20 0 20 40 60 80 I00 0 100 200 300 400 one of four instruments on the $ s Compton Gamma Ray Observatory (CGRO), launched into Earth orbit by FIGURE51.--Examples of four intense gamma-ray bursts observed by BATSE. the space shuttle on April 5, 1991. BATSE consists of eight detector ever the spacecraft is within one of The first catalog of gamma-ray bursts modules, placed at the corners of the several high-latitude regions identi- observed with BATSE has recently CGRO spacecraft. The CGRO is in a fied as having a high probability of been submitted for publication circular orbit, with an inclination of triggers caused by particle precipita- (Fishman et al. 1993). This catalog 28.5 degrees. The initial altitude was tion. On April 19, 1991, the burst contains the 260 bursts that satisfied 450 kin, and decreased to approxi- trigger was enabled, and BATSE the onboard trigger criteria from mately 350 km by June 5, 1993. Burst began to record gamma-ray bursts at April 21, 1991, until March 5, 1992. triggering is disabled whenever the a rate of about 0.8/d. An early and Figure 51, from the burst catalog spacecraft passes through the South quite unexpected finding was that illustrates the extremely complex Atlantic Anomaly (SAA), and when- the distribution of burst sources is temporal structure found in some isotropic (fig. 50), but there is a gamma-ray bursts. +90 deficiency of weak sources, presumably at larger dis- Meegan, C.A.; Fishman, G.J.; Wilson, tances (Meegan et al. R.B.; Pacicsas, W.S.; Pendleton, 1992). No known galac- G.N.; Horack, JM.; Brock, M.N.; tic population has and Kouveliotou, C. 1992. Nature 355:143. +180 _-180 such a distribution, leading to speculation that the sources either Sponsor: Office of Space Science reside in a previously unknown very large -90 galactic corona or they are at cosmological FIGURE50.--The celestial distribution of 447 distances. gamma-ray bursts. 79 Research and Technology 1993

X-Ray Astronomy A second instrument under develop- The group continues the develop- Research ment is a hard x-ray imaging polar- ment program in hard x-ray optics imeter. This device utilizes an and has recently x-ray tested a intensified CCD camera to image Kirkpatrick-Baez mirror assembly Brian D. Ramsey/ES65 the photoelectron tracks produced fabricated from high-quality silicon 205-544-7743 by x-rays interacting in the detector wafers. The intention is to increase Martin C. Weisskopf/ES01 gas. The imaging is made possible the high energy response of this as- 205 -544-7740 through the development of a spe- sembly through the in-house applica- cial kind of gas counterIan optical tion of muttilayer technology and The laboratory work of the x-ray avalanche chamber--that produces software has been developed to aid astronomy group has focused prima- extremely large quantities of light in defining the necessary coating rily on the development of new photons (>107 ) under x-ray irradia- materials, thicknesses, and number detectors for x-ray astronomy. Three tion. Analysis of the initial ejection of layers. instruments are currently under de- direction of the photoelectron per- velopment, all based on variants of mits a measure of the polarization of The MSFC x-ray astronomy group is the gas-filled proportional counter. the incident x-ray photon. A large- continuing to collaborate on the The first of these is a large-area im- area (30 by 30 cm) flight version is Stellar X-Ray Polarimeter experiment, aging proportional counter that is currently under construction for scheduled to fly aboard the Spec- flown on a high-altitude balloon as flight on a high-altitude balloon in part of a collaboration with Harvard 1994-95. trum-X-Gamma spacecraft in 1995. Monte Carlo simulations have been College Observatory and serves as performed that detail the instru- a test-bed for new techniques devel- oped in-house to improve energy ment's sensitivity for various cosmic The third instrument under develop- sources of interest. These simulations resolution, spatial resolution, and ment is a hybrid detector that com- background rejection. These tech- bines a sodium iodide/cesium iodide have recently been used to predict, for example, the effects of changes niques include advanced body phoswich detector with an optical in the composition of the detector materials for lower instrument back- avalanche chamber. The chamber is fill gases. ground, special gas mixtures (Pen- optically coupled to the front of the ning mixtures) to improve energy phoswich and provides response at resolution, fluorescence gating to low energies, while the sodium io- Under the auspices of the MSFC reduce background, and lately, the dide takes over at energies where Center Director's Discretionary Fund, use of microstrip technology to pro- the gas becomes transparent. Both the group has built four microwave vide high-uniformity electrode read- sections of the hybrid are read out receivers, together with associated out and fine electrode structure by a common set of photomultiplier optics and electronics, to measure for enhanced performance. This tubes under the phoswich. The net the magnitude of the Sunyaev- latter technology is being developed result is a broad band instrument Zel'dovich effect. This effect, a spec- both in-house to investigate and with high sensitivity for hard x-ray tral distortion of the primordial develop new readout techniques, imaging from 25 to 600 keV. This background radiation, offers a pow- and out-of-house for the production instrument, also a collaboration with erful probe of the cosmic distance of a large-area flight version, cur- Harvard College Observatory, is scale and provides a measure of the rently scheduled for delivery in 1993. scheduled for flight in 1995. size and age of the universe. The

8O Research Programs

instrument under development com- The Observation of Direct This was the dominant background bines recent advances in microwave Electron-Positron Pairs source that satisfied the microscope technology with existing interferom- scanning criteria for a "candidate" eters and provides a novel approach by Relativistic Heavy Ions direct electron-positron pair event. to an exceptionally difficult measure- in Nuclear Emulsion The 200 GeV/n oxygen data, which ment. The first observations are sche- are the least contaminated by the KO duled for 1993 at the Owens Valley James H. Derrickson/ES64 electron background (approximately interferometric telescope array. 205-544-7698 15 percent), that are presented in figures 52 and 53 show the total The group built an x-ray detector The direct Coulomb electron- direct-pair energy distribution and system to test the replicated optics pair-member emission angle distribu- positron pairs produced along the currently under fabrication by the tion, respectively. The broken line is tracks of heavy ions in nuclear emul- optics group at MSFC. The detector the theoretical prediction without the sion have been the subject of recent has better than 500 t.t spatial resolu- KO electron contamination and is theoretical and experimental studies. tion at 8 keV, which corresponds to based solely on the total oxygen ion The European Center for Nuclear 20 arc seconds for the replicated path length scanned. In the near Research (CERN) exposures of emul- optic's focal length. The tests, con- future, the KO electron contamina- ducted by the X-ray Astronomy sion plates to oxygen ions at 60 and tion will be included in the Monte 200 GeV/n and sulfur ions at 200 Branch, were scheduled to be com- Carlo simulation of the energy and pleted in 1993. This work has led to GeV/n have been analyzed to yield emission angle distributions for all the development of a very large set the direct-pair cross section, energy, the pair data sets. Because the of software tools that have wide- and emission angle distributions. The chance KO-KO electron background spread application in, for example, measurements at 200 GeV/n compare is not a serious problem for the the design of x-ray optics or the well with recent theoretical calcula- 200 GeV/n oxygen case, the direct- design and evaluation of x-ray tions, when corrected for the back- pair energy distribution and the pair- instrumentation. ground due to the chance association member emission angle distribution of two knock-on (KO) electrons. satisfactorily match the theoretical Austin, R.A., and Ramsey, B.D. 1993. Optical Imaging Chamber for X-ray 16

Astronomy. Optical Engineering I"! w)l. 32, no. 8. I I 14 Ramsey, B.D. 1992. The Microstrip Pro- portional Counter. SPIE 1743: 12 96-10.7. '1 I Ramsey, B.D., Austin, R.A.; Minamitani, I 10 I 1".; Weisskopf, MC.; Lum, K.H.S.; i I and Manadhar, R.P. 1993. A Hybrid Gas Detector for Hard X-ray 8 Astronomy. SPIE 2006, in press. .i i B _ 6 Sponsor: Office of Space Science

University Involvement: Harvard 4 University

2

0 0 S0 100 150 200 250 Total Pair Energy (MeV)

FIGURE52.--Comparison of the measured direct pair energy distribution with theory (broken line) for oxygen ions at 200 GeVn. 81 Research and Technology 1993

7O cosmic ray ions has been proposed by the Japanese-American Coopera- tive Emulsion Experiment (JACEE) 6O collaboration. This collaboration includes scientists from MSFC, and from the United States, Japanese, and SO Polish universities. The JACEE "pair- meter" consists of a multilayer stack of thin (50-200/.tm) lead plates, low- | 40 - I I density spacers (thickness to be de- i,m _a termined), emulsion plates (50 btm), and CR39 tracking layers. The detec- | ao tor is designed to produce more z direct pairs per mass thickness. For cosmic ray energies above 1013 eV/n, 2O the direct pairs will be emitted pre- dominately in the forward direction and will be preferentially detected in 10 the emulsion layers. A Monte Carlo simulation of the pair-meter is in progress to evaluate its practical 0 _ I"'1 0 10 20 30 40 SO 60 70 energy resolution. The pair-meter will be part of the target of a large Electron(positron)/Emissio.Angle(deg) area emulsion chamber to be flown

FIGURE53.--Comparison of the measured emission angle distribution for on a long duration balloon flight in Antarctica in the 1993-94 austral the pair members with theory (broken line) for oxygen ions summer season. The data collected at 200 GeVn. on this JACEE balloon flight and the simulation will be used to assess the TABLE3 .-- Measurements and theoretical calculation of the interation mean performance of the pair-meter. free path for producing direct pairs from oxygen ions at 200 GeV/n where the total pair energy is greater than 4 and 10 MeV. The Asakimori, K et al. 1993. Twenty-third length of oxygen ion track scanned was 565 cm International Cosmic Ray Conference (ICRC), Calgary, Canada.

Derrickson, J. et al. 1993. Twenty-third ICRC, Calgary, Canada, 1992. Sub- mitted to Physical Review A.

Eby, P.B. 1991. Physical Review A 43:2258. 1992. Submitted to Nuclear InstrT_ments and Methods, Sec. B. calculations. The measured and An objective of this study has been theoretical direct pair yield for to evaluate the possibility of measur- 200 GeV/n oxygen is listed in table 3 ing the primary energy of extremely Sponsors: Office of Space Science for two pair energy thresholds, relativistic cosmic rays (E>1013 eV/n) and Marshall Space Flight Center 4 and 10 MeV. The theoretical pair utilizing the direct-pair method. A Director's Discretionary Fund. yield includes the chance double-KO detector for measuring the direct electron background. pairs along the tracks of heavy

82 Research Programs

PrimaryCosmicRay--_ Cosmic Ray Proton Z_>I Spectrum Changes at E_>1012eV\ 4 x | 0 TM Electronvolts Double-Cooled MeasureZ by ' tChoroo 8 RayCountingin Thomas A. Parnell/ES64 EmulsionCR39ElchoblePlates Emulsionsand 205-544-7690 TrackDetectors Detedor EtchPil SizeinCR39

The cosmic-ray group at MSFC performs balloon-borne experiments to study the composition, energy spectra, and interactions of cosmic InteractionProbability Emulsion -0.2 for Protons ray nuclei above 10'e eV (1 TeV). Target PlasticPlates_,, -0.9 for IronNuclei This research is performed with and/or colleagues in the United States, MetalPlates Japan, and Poland, who form the JACEE collaboration that has flown 11 experiments since 1979. These Pdmory Fragments, instruments consist of large passive detector assemblies (emulsion cham- Prodwcod_±, GanmmRays From_o DecaySpread bers). Because of the steep energy Honeycomb._ Out so1heyMay beMeasured spectra of cosmic rays (approxi- Individually_)(Typical) mately proportional toE-'V), the in- Spacer =2 x ! 0-3 Radions vestigation of cosmic rays above LeadPlates at I0 t2eV/Norleon 1 TeV requires large exposure factors (area × solid angle × time). The JACEE balloon-borne experiments Emulsions have achieved nearly 1.0 m2/sr/h X-royfilm"_ GammaRaysProduce above 38 km in 11 balloon flights Copiouse± y's inLead.No. of from the United States, Japan, Austra- Calodmetere± Countedin Emisionsor lia, and the Antarctic. The typical X-ray FilmOpticalDensity emulsion chamber is 0.8 m 2 in area, Measured= £ Ey approximately 20-cm thick, and con- tains 600 kg of material. It includes multiple layers of photographic emulsion, acrylic plates, x-ray film, passive nuclear track detectors EmulsionChambers (CR39), and lead plates. FIGURE54.--A schematic of an emulsion chamber of Following the flights, the photo- the type flown by the JACEE collaboration. graphic materials and other passive track detectors are developed and, either the end of confinement of after initial analysis of the x-ray film from hydrogen (H) through iron (Fe) with microdensitometers at MSFC, have been analyzed. The JACEE cosmic ray nuclei by the weak galac- are divided among the collaborators group has produced the highest tic magnetic fields, or due to the for microscope measurements of energy direct data on the composi- inability of the processes that accel- particle tracks in the emulsions and tion and spectra, extending by a erate cosmic rays to push them to other passive detectors. The analysis factor 10 in energy above other ex- higher energies, or perhaps contribu- determines the atomic number of periments. It has been known from tions from both. These uncertainties each incident nucleus (above a cosmic ray air shower experiments have motivated measurements of the threshold of approximately 10 Je eV), (large arrays of detectors on the composition and spectra of cosmic rays to increasingly higher energies. the energy it deposits in the chamber ground), that the cosmic-ray spec- following a nuclear interaction, and trum extends to -102° eV, but the the characteristics of the mesons and spectrum has a bend (intensity de- The JACEE collaboration has for the other particles produced in the inter- crease) around 3x10 _seV. This bend first time produced data that show a action. Approximately 1,000 nuclei has been speculated to be due to clear spectral bend for an individual

83 Research and Technology 1993

103 element, the H nucleus (fig. 54). m Discovery of X-Ray This surprisingly sharp bend occurs Nova Persei 1992 at approximately 4x101_ eV (40 TeV). An additional surprise is that the (GRO J0422+32) With helium spectrum (fig. 55) shows the Burst and Transient ',_ 10_ no evidence of change to beyond Source Experiment 40 TeV. If the spectral bend in the f I air shower experiments is due to the end of galactic confinement or B. Alan Harmon/ES66 z acceleration, the protons should 205- 544-4924 I I I I I I J 101 bend around 100 TeV, with ion I0 100 nuclei bending at around 260 TeV In August 1992, a very bright x-ray X Energy(TeV/n) (-3 10 Is eV). nova (GRO J0422+32) appeared in the constellation of Perseus. It was The JACEE observation of the proton discovered about 3 d into its out- Protons(JACEE1-8) spectral bend is unambiguous in the burst, using the BATSE on the CGRO. data, but its implication is uncertain. E_2.74±0.06" ,. ,, The JACEE collaboration plans fur- Large occultation steps were ob- served in the raw data, and also 103 ther experiments with larger cham- bers and longer duration balloon intense flickering of the source flights. Further measurement and caused frequent triggering of the exposures approximately 30 times instrument into the burst mode. The that already achieved would extend intensity of GRO J0422+32 was 10_ I I I I I I I I the composition and spectra data 10 100 monitored with the Earth occultation above 10_s eV and would confirm the Energy{l'eV/n) technique. (A description of the acceleration processes and the galac- method applied to BATSE can found tic containment models. Figure 55.--Comparison of in Research and Technology 1992.) The integrated daily flux between 20 {a) helium and Asakirnori, K. et al. 1993. Twenty-third and 300 showed the source rising in b} proton spectrum ICRC. Calgary, Canada. rom JACEE experiments. intensity to its primary maximum in Parnell et al. 1989. Advances in Space about 5 to 6 d, which then decayed Research vol. 9, no. 12:45-54. exponentially with a characteristic time of 41 d. At its peak, the source Sponsor: Office of Space Science was about 3 times brighter than the brightest persistent hard x-ray sources in the sky--the Crab Nebula and Cygnus X-1. In December 1992, about 120 d after the initial outburst, a second maximum appeared in the GRO light curve, followed by a de- crease in intensity at the same rate observed after the primary maximum (fig. 56). The source was no longer visible to BATSE after April 1993.

The light curve of GRO J0422+32 is typical in shape (fast rise, exponen- tial decay, secondary maximum) of x-ray novae because they resemble the optical light curves of classical novae. The objects that produce the outbursts are thought to consist of

84 Research Programs

1.000 ...-.'...... ,

""'"'.. BA1SEOccultationAnalysis

"""''".v..., 20-300 keV l

iii i oI olllll ° IIII

I %' " k II i I Ill iiI diIIIi "il Ill I I

"""ii'I IPW 'I'III'lilI_II ",llti illlinj

0.100

i O.OlO ' 11

0.001 1 I I I I 8,850 8,900 8,950 9,000 9,050 9,100 Truncated Julian Date (JD 2,440,000.5)

FIGURE56.--Hard x-ray light curve for GRO JO422+32.

two stars (a binary system), one of added to our knowledge of x-ray is flickering in x-rays on short tin]e- which is a normal hydrogen/helium- novae in binary systems. Specifically, scales (milliseconds to seconds) that burning star and the other a compact the spectral and temporal character- appears as low-frequency noise in a object, which can be a neutron star istics that are considered indicators power density spectrum. The flicker- or black hole. The cause of the out- of potential black holes have been ing and very hard spectrum above bursts is not well understood, but identified in x-ray novae. One char- 20 keV were both observed in the suggested explanations inw)lve ei- acteristic is a bimodal spectral behav- outburst of GRO J0422+32. The soft ther a large mass transfer from the ior, where, at times, the source component below 10 keV, however, normal star or perhaps an accretion spectrum is dominated by a hard if present, is outside the energy range of the BATSE instrument. disk instability (Chan et al. 1993). power law component in the x-ray Both scenarios result in a sudden regime (few" keV to 100 keV, spectral increase in matter accreted onto the index approximately -2), usually The spectral behavior of the x-ray compact object. steepening in the gamma-ray regime novae can vary from source to sourc(. _. (fig. 57). At other times the spectrum The spectrum of GRO J0422+32 can All-sky monitoring in recent years by is dominated by a very soft, black- be described reasonably well with an several spacecraft such as Ginga, body component in the 1-10 keV optically thin bremsstmhlung model Granat, and now the CGRO, has energy band. Another characteristic or a Comptonization model. Except

85 Research and Technology 1993

10-1 for a softening of the spectrum near Infrared Space the primary maximum, the spectrum IGROJ0422+32II Astronomy and was extremely stable in shape during the long decay period and showed Space Research 10-2 no strong changes in the spectrum ! during the onset and decay of the Charles M. Telesco/ES63 I December secondary maximum 205-544-7723 ._ 10-3 (Paciesas 1993). This is in contrast to GRS 1124-68 (X-ray Nova Muscae 1991) where BATSE detected a dis- In 1993, infrared (IR) astronomy at MSFC has focused on three research tinct hardening of the spectrum dur- areas: (1) scientific and technical 10-4 ing a secondary maximum in the participation in the European Space light curve of this source 150 to 200 d X Agency's (ESA's) Infrared Space after the initial outburst in January 1991 (Paciesas 1993). Observatory (ISO) program, (2) the 10-5 extensive observation of star-forming regions in other galaxies and of The spectral and temporal character- protoplanetary disks around other istics observed by BATSE represent stars using the previously developed clues, although not proof, that the 10-6 MSFC mid-IR camera, and (3) the SO 100 200 SO0 compact object in the GRO J0422+32 development of a new advanced IR system may be a black hole. More Energy(keV) camera for astronomical and shuttle- observations of x-ray novae, both in related observations. the hard x-ray/gamma-ray regime, 10-2 and at other wavelengths, are The MSFC IR astronomy program INovaMuscaeI needed. has continued to contribute to the development of the ISOPHOT, an IR Chan, W.A.; Livio, M.; Gehrels, N. 1993. spectrophotometer that will be one of the four IR instruments to be _. t0-3 The Secondary Maxima in Black flown aboard ESA's ISO, scheduled i Hole X-ray Nova Light Curves: Clues for launch in 1995 (fig. 58). ISO will I Toward a Complete Picture. Ap. J. >. 408:L5. be the next major IR space experi- i ment and the only one scheduled to be launched this decade. Negotia- 10-4 Paciesas, W.S. et al. February 1993. tions between NASA and ESA are BATSE Observations of Black-Hole nearing completion, which will make X-ray Binaries. Presentation at Inte- NASA a full partner in ISO. .i gral Workshop, Les Diabterets, t. 10-5 Switzerland. The MSFC ISO responsibilities have included the definition and coordina- Stinson, H., ed. Research and Technology tion of a broad range of astronomical Report 1992: Annual Report of the observations to be carried out by the Marshall Space Flight Center, NASA international ISOPHOT team of 10-6 scientists during their guaranteed SO 100 200 500 TM-103599, p. 29. observing time. Those planned Energy(keV) observations include the search for Sponsor:. Office of Space Science the illusive substellar brown dwarfs FIGURE57.--Photon spectra of and the determination of the energy two x-ray novae: output of some of the most distant GRO J0422+32 galaxies in the universe. A major and Nova Muscae. MSFC task is to establish the set of celestial objects that will serve as far-IR photometric standards for ISOPHOT during the mission. This task has required that MSFC astrono- mers carry out an extensive pro- gram of airborne and ground-based IR observations using the NASA Infrared Telescope Facility (IRTF) 86 Research Programs

this feature around the star Beta Pictoris is opening the way to a better understanding of the evolution Sunshade Cover of disks that may be in the process (ReleasedAfterLaunch) of forming planets. As part of a broad survey of stars like Beta Pictoris, the He-FInsh OpticalWindows andFilters silicate feature has recently been dis- covered around another star, 51 Secondar Ophiuci, which demonstrates that He-FlushInlet the silicate feature may be ubiqui- tous enough to permit statistical Tanks,Telescope,and HeITank(60I) analyses of the feature in the context Instruments of evolution of planetary systems. Cassegroin hields Significant progress has been made in the development of an advanced, Vessel high-speed mid-lR camera and spec- trometer. This cryogenically cooled detector system, which will be an extremely versatile instrument using HeIITank(2300I) a state-of-the-art arsenic-doped sili- PrimaryMirror con detector array containing 10,000 SupportStruduresfor pixels, will permit rapid imaging with very high spatial resolution, as Tanks,Telescope,and Instruments well as multiresolution spectroscopy. In addition to its use for astronomi- cal observations, this new' camera ScientificInstruments OpticalSupport will provide ground-based imaging Strudure of the orbiting space shuttle in order to better understand the environment Ught-Tight PyramidMirro_ QuadrantStarSensor of the shuttle during its missions. The Shield system fabrication is nearing comple- ISO PayloadModule tion, with the first field operation scheduled at the IRTF in 1993. FIGURE58.--The ISO, to be launched in 1995. Hawarden, T.G.; Cummings, R.O.; on Mauna Kea, HI, and the NASA intense episodes of star formation in Telesco, C.M.; and Thronson, H.A. Kuiper Airborne Observatory to de- the cores of many galaxies. In collab- 1992. Optimized Radiative Cooling termine the spectral energy distribu- oration with BATSE scientists at of Infrared Space Telescopes and tions of potential candidates. In early MSFC, the first mid-IR detection of a Applications to Possible Missions. 1993, extensive theoretical analysis transient gamma-ray source, GRO Space Science Review 61:113-44. and modeling of the data obtained J0422+32, was made with the MSFC so far indicated for the first time that IR array at the NASA IRTF. These Telesco, C.M.; Dressel, L.L.; and selected asteroids will be suitable long-wavelength observations will Wolstencroft, R.D. 1993. The Genesis of Starbursts and Infrared primary photometric standards for constrain the structure of the outer ISO. region of the accretion disk which Emission in the Centers of Galaxies. may surround a black hole and emit 40. I. The MSFC mid-IR camera, with 20 the gamma radiation. extremely sensitive bolometer de- Telesco, C.M.; Pina, R.; Fajardo, S.; tectors, has been operational since This year the MSFC mid-IR camera Fishman, G.; Kouveliotou, C.; and 1985. This camera has permitted a extended the discovery, made with Van Paradijs, J. 1992. GRO .10422+32. broad range of astronomical observa- the same camera at the IRTF, of the International Astronomical Union tions at major observatories, includ- "silicate feature" from a protoplane- ([AU), circular no. 8613. ing the only extensive program to tary disk. This broad spectral feature in the mid-IR is a signature of silicate map regi(ms of star formation in Sponsor: Office of Space Science other galaxies. Analysis of these dust grains, and is an important unique IR images has led to a recog- diagnostic of particle sizes and evo- nition of the causes of extremely lutionary histories. The detection of 87 Research and Technology 1993

III I I Microgravity Science and Applications

Electromagnetic Field Real-Time X-Ray To date, interfacial morphologies and Effects in Semiconductor Microscopy of particle-interface interactions in the respective metallic, optically opaque Crystal Growth Solidification Processes systems have been deduced from postprocess metallographic analyses Martin P. Volz/ES75 Peter A. Curreri/£S75 of specimens. Thus, little information 205-544-5078 205-544-7763 is obtained about the detailed dy- namics of the processes. These in- The quality of all bulk-grown crystals Physical processes that occur at, or vestigations have been considerably depends on mass and heat transfer near, interphase boundaries during augmented by real-time observations processes present in the crystal solidification or other phase transfor- of transparent materials; yet, since growth system. In particular, gravity- mations, play a major role in the some of the interfacial and transport driven convective flows in the melt determination of many of the tech- properties of these materials differ affect the uniformity of the grown nologically important properties of greatly from those of metals and semiconductor and the distribution solids. In this advanced technology semiconductors, the results are not of defects and impurities. In most development program, MSFC will necessarily representative of these instances, the force of gravity has develop a high-resolution x-ray mi- opaque systems. proven to be detrimental to the qual- croscope to view, in situ and in real ity of the grown crystals, and thus time, interfacial processes in metallic The XTM to be developed will there have been numerous studies systems either during freezing or achieve magnification through pro- of semiconductor materials in low- solid-solid transformations. The jection. Figure 59 schematically indi- gravity environments. The purpose X-Ray Transmission Microscope cates the major components of the of this investigation is to examine the (XTM) will operate in the hard x-ray system and their placement. A metal effects that an additional force has range (10 to 100 keV) and achieve sample (thickness on the order of on gravity-driven fluid flow pro- magnification through projection. 1 mm) is contained in a specially cesses. This additional force is the Lorentz force and is the result of combined electric and magnetic Mkr0f0cusX-raySource fields. RadiationShielding Work has begun on developing a growth cell that can accommodate large current densities and that will be placed in a transverse electromag- net. Current research efforts are fo- SampleinCrucible cused on examining the criteria for Furnaceand the onset of thermal instability as a I I DivergingBeam _ TranslationStage function of electric, magnetic, and / gravitational field strength in electri- I I

cally conducting liquids. Also, the i I possibility of using externally applied i I electromagnetic fields to influence I fluid motion in the meh, the rate of solid phase accrual, and the shape of the solid/liquid interface is being assessed. Indium antimonide (In-Sb) and gallium indium antimonide (Ga- CameraController In-Sb) are the semiconductor alloys and that are being used in the initial ImageComputer studies.

Sponsor: Marshall Space Flight FIGURE59.--Schematic of XTM prototype showing configuration Center Director's Discretionary Fund of the various components.

88 ResearchPrograms

designed, high-transmittance cru- influences of convection and sedi- The Effects of mentation on solute distributions, cible. A high-temperature furnace on Temperature on a translation stage imposes a tem- interface morphologies, particle- perature gradient onto the sample. interface interactions, segregation, Tetragonal Lysozyme The solid-liquid interface is posi- droplet formation, and coalescence. Face Growth Rates tioned in proximity to the focal spot In opaque materials, the interpreta- of a microfocus x-ray source. The Marc L. Pusey/ES76 diverging x-ray beam permeates the tion of solidification phenomena has 205-544-7823 sample and the resulting shadow been restricted to metallurgical or falls on an x-ray image converter. radiographic analysis after solidifica- Protein crystals are typically grown tion. Thus, little information is ob- The resulting visible image is con- by methods that involve an uncon- vetted to a digital image by a CCD tained about the detailed dynamics trolled increase in the concentrations of the processes. This shortcoming camera and stored in a computer. of both the protein molecule and the impedes fundamental research and This image is displayed on a high- agent(s) used to precipitate it from resolution monitor, either in real important technology developments, solution. Recently, however, the use since the phenomena that occur at time or after further processing (con- of temperature as a more control- interphase boundaries during solidifi- trast enhancement, filtering, etc.). lable means of effecting nucleation cation determine many of the impor- Hard copies of the images are ob- and controlling the crystal growth tant properties of solids. Similar tained either photographically from process has attracted attention. How- impediments arise in studies of solid- the high-resolution monitor or, with ever, what is not known is precisely solid processes. some loss of quality, from a video how protein crystal growth rates printer. Sponsor= Office of Life and Micro- change with temperature or any of the other variables that may be em- NASA's Materials Science and Appli- gravity Sciences and Applications cations Division (MSAD) currently ployed. Scientists at the biophysics University Involvement: [ In iversity laboratory at MSFC have initiated a supports a large number of research of Alabama in Huntsville projects that are concerned with long-term study of these parameters. gravity-induced phenomena in mate- rials processing. These include the Because protein crystal growth is typically a slow process (maximum growth rates of approximately 10-2 !am/s), detailed studies of the face growch rates required that a microscopy system be devised that

89 Research and Technology 1993

-1 Kinetics of Diffusional Droplet Growth in a -2 >K x X Liquid/Liquid Two-Phase _xAX_o • e"_ C_) 0 0 ,..,, aso- System _.-3 x ,

• Xx XX X Barbara R. Facemire/ES74 205-544-7810

0 0 The objectives of this work are: -6- 0 0 (1) to improve understanding of -7 l I I I I I the influence of diffusional droplet 0 10 20 30 S 10 15 2O coarsening, or Ostwald ripening, on Concentration,mg/ml Supersaturation,C/Cs phase-separation processes and mi- crostructure evolution; (2) to ascer- FIGURE60.--Effects of temperature on the (1 1O) face growth rate (fgr) of tain the effect of gravity on this coarsening; and (3) to perform mod- tetragonal lysozyme at pH 4.0, 5% sodium chloride (NaCI). eling studies to ser_,e as predictive tools. A transparent metal model allowed us to follow multiple crystal the growth rates become essentially system, succinonitrile/water (SCN/ growth rates during one experimen- independent of temperature and H20), allows direct observation of tal run. We have recently completed only become a function of the pro- the phase-separation events of inter- such an apparatus (Pusey 1993) and tein concentration. Thus, control of est. The SCN/H20 system has an have been successfully using it for growth rates by temperatures can isopycnic point (temperature where the past year. The system consists of only be achieved at low-protein the densities of the two fluid phases a horizontally mounted video micro- concentrations. are equal) near 42 °C and offers the scope, with the growth cell being a opportunity to perform experiments thermostatted block that hangs down The right panel shows the same data on the ground where gravity-driven into the microscope's focal plane. except that they are plotted using a The thermostatted block is mounted supersaturation ratio axis. In this sedimentation and buoyancy can be case note that the positions of the greatly reduced. Using holography to on a pair of computer-controlled record the entire test-cell volume at translation stages to adjust its posi- lines have been reversed. We have tion in the vertical and transverse found that for tetragonal lysozyme selected times during the coarsening process makes it possible to obtain planes (x and y axes). The micro- conditions that result in a reduction data on droplet size distributions for scope system is also mounted on a of the proteins, saturation concentra- a large number of droplets at any translation stage that is used for tions also result in a shift of this plot given point during the coarsening focus control. Positions of crystals to to the right; i.e., higher relative process. The holograms serve as an be measured are preloaded into the supersaturations are required to archive "storing the experiment" at controlling PC. Measurement consists achieve equivalent face-growth rates specific instances in time. of the system focusing on each crys- when one goes to conditions that tal in turn and measuring the dis- give lower solubilities. Whether this tance across the parallel faces of is a general rule for proteins, or even A quench experiment was perfommd interest. other forms of lysozyme, remains to in a narrow path-length test cell. The be determined. path length of the cell was 100 lam Figure 60 shows the results of 110 (fig. 61). (The large number of drop- face-growth rates obtained from Pusey, M.L. 1993. A Computer Controlled lets produced in a quench and the tetragonal lysozyme as a function of Microscopy System for Following requirements of the holographic Protein Crystal Face Growth. Revi_v temperature. The left panel shows technique dictate the narrow cell so of Scientifi'c In._truments, in press. the data plotted as a function of that the sample will be transparent.) absolute protein concentration. As ex- Due to the test-cell geometry and the pected, lower temperatures required Sponsor: Office of Life and Micro- method of quenching, the droplets lower protein concentrations to gravity Sciences and Applications nucleated on or near one wall and achieve equivalent growthrates. Note, were attached there for the duration however, that at about 20 mg/mL,

90 Research Programs

accurately predicting the scaling laws, does not perform as well in predicting individual droplet lifetimes (R versus t). A dipolar approximation correction to the monopole calcula- tion better models local effects.

This experiment, while designed to reduce the influence of gravity, is not entirely free of gravity's effects. As droplets grow and shrink, con- centration gradients (and thus den- sity gradients) form, which can lead to gravity-driven convective flows. Additionally, most materials of com- mercial or technical interest are not quenched to an isopycnic point. One goal of this investigation is to design a flight experinaent to perform a similar study in microgravity far from the isopycnic temperature. The diffu- sional process is slow, and king times are required to obtain data from quench experiments. This sug- FIGURE6 1 .--This series of photographs, spanning an experiment time of gests that quench experiments would about 4 mo, shows diffusional growth of droplets in a 1O0 _n be best performed on the space path-length test cell. The smaller succinonitrile-rich droplets lose station or a retrievable satellite. For mass through diffusion to the larger droplets. Droplet number Spacelab missions, an experiment decreases with time as t -3/4 and the average droplet radius consisting of tethered droplets is increases as t TM. under consideration that will require the deployment of nl droplets. Such of the experiment. This situation cellent agreement with the scaling small w)lumes are required R_r a further reduced any possibility of laws accompanying ripening of 3-D measurable change in diameter to gravity-induced droplet movement. droplets located on a 2-D substrate. occur within the time limitations of a The 152 holograms taken during the This result agrees with mixed dimen- Spacelab mission. During the past experiment follow the ripening pro- sionality scaling predictions from the year, several methods of deploying cess for 1 X 107 seconds (approxi- literature and match well the geom- nl droplets have been evaluated. mately 4 too). Preliminary analyses etry of the experiment. The litera- These technologies were developed of this experiment are currently be- ture also reveals agreement with for biological applications, such as ing prepared for publication. For mixed dimensionality in modeling cell injection, and appear promising tractability, these results are based the development of thin films of for droplet fornaation. Methods of iso- on measurements of droplet size semiconductor materials. lating these droplets from the injec- distributions for about 5 percent of tion volume are under investigation. the volume available for study in Most modeling schemes are based each of the 14 selected holograms. on global averages; however, the Fradkov, V.E; Mani, S.; and Glicksman, Results indicate the number of drop- local environment around any given M.E. November 1993. Mixed Dimen- lets of discrete phase decrease with droplet can significantly influence sional Coarsening of 3-I) Droplets time according to N(t)=At -°'-_-_and the resulting microstructure in that by 2-D Diffusion. To be presented that the average droplet radius location. An estimate of the field sur- increases with time according to rounding each droplet based on a at Materials Research Society meet- R(t)=Bt '_2'_. These results are in ex- monopole approximation, while ing, Boston, MA.

91 Research and Technology 1993

Frazier, D.O., and Facemire, B.R. 1989. Separation of Large DNA and make their migration velocity a Non-Ideality Near the Monotectic Molecules in Free Fluids function of their length in order to Composition of a Miscibility-Gap achieve separation. Type System: Succinonitrile-Water. Thermochimica Acta 145:301-29. Percy H. Rhodes/ES76 The objective of this research is to 205-544-7807 Frazier, D.O.; Facemire, B.R.; Loo, B.H.; investigate the orientation in free Burns, D.; and Thiessen, D.B. 1990. fluid of long-chained DNA molecules The current challenge for biological Solidification Behavior of Impurity- in the presence of high-strength Doped Succinonitrile Solutions in separation processes is the isolation electric fields (in excess of 100 V/cm). High-Surface Area, Low-Bulk Vol- of the intact DNA molecule from The goals are to quantitatively deter- ume Containers. Journal of C_,stal individual eukaryotic chromosomes. Growth 106:101-15. mine the relationship between elec- The process of mapping and se- trophoretic mobility, the applied field quencing the entire human genome Rogers, J.R.; Downey, J.P.; Witherow, strength, and the length of the indi- W.K.; Facemire, B.R.; Frazier, D.O.; requires the separation by electro- vidual linear DNA molecules subject Fradkov, V.E.; Mani, S.; and phoresis of large (long-chained) to imposed electric fields. This re- Glicksman, M.E. A Study of Diffusive DNA molecules and their fragments. search will determine if electro- Droplet Growth in a Narrow Test Since the total sequence is essentially Cell Using Holography. To be sub- phoretic separation of DNA in a free in a three-billion-base "message," it mitted to J. Colloid Interface Sci. fluid is possible and, thus, access the is of vital importance to execute the potential of space-based separation Rogers, JR; Downey, J.P.; Witherow, separations involved with great of large DNA molecules. W.K.; Facemire, B.R.; Frazier, D.O.; speed. Fradkov, E.V.; Mani, S.; and Grossman, P.D., and Soane, D.S. 1990. Glicksman, M.E. July 1993. A Study Electrophoretic separation is en- Orientation Effects on the Electro- of Diffusional Growth in a Liquid- phoretic Mobility of Rod-Shaped Liquid Miscibility-Gap System Using hanced in low gravity by virtue of Molecules in Free Solution. Analyti- Holographic Techniques. A poster the absence of thermal convection cal Chemistry 62. presentation at the Gordon Confer- (Rhodes and Snyder 1982). On Earth, ence. DNA molecules up to a few mega- Oliverd, B.M.; Baine, P.; and Davidson, N. base pairs are currently being sepa- Rogers, J.R. et al. October 1993. A Study 1964. Electrophoresis of Nucleic of Diffusional Growth in a Liquid- rated using gel electrophoresis. The Acids. Biopolymers 2:245-57. Liquid Miscibility-Gap System Using gel structure is sufficiently rigid to l tolographic Techniques. To be overcome the detrimental effects of Rhodes, P.H., and Synder, R.S. 1982. The Effect of Small Temperature Gradi- presented at the 45th Southeast gravity-induced thermal convection. ents and Flow in a Continuous Flow Regional Meeting of the American However, this process is tedious and Chemical Society, Johnson City, TN. Electrophoresis Chamber. Materials requires runs that take about a week Processing in Reduced Gravity Envi- Rogers, J.R. et al. Septemtxer 1993. Difl"u- to complete (Smith et al. 1987). By ronment of Space.'Elsevier Science Pub. Co. sional Growth of Succinonitrile-Rich processing in low gravity and using a Droplets on a 2-D Surface in a free fluid, the time required for sepa- Succinonitrile-Water Miscibility Gap Smith, C.L.; Matsumoto, T.; Niwa, O.; ration can be reduced many orders System. To be presented at the 7th Kico, S.; Fan, J.D.; Yanagida, M.; Annual Alabama Materials Research of magnitude. A significant problem and Cantor, C.R. 1987. Nucleic Conference, Normal, AL. in processing large DNA molecules Acids Research 15:4481439. in a free fluid, however, is that Sponsor: Office of Life and Micro- all molecules migrate at the same Sponsor.- Office of Life and Micro- gravity Sciences and Applications speed, regardless of their length gravity Sciences and Applications (Oliverd et al. 1964). Some way must be found to orient these molecules

92 Research Programs

Highly Rarefied Solids in Microgravity: Toward the Limits for a Solid With Zero Volume and Infinite Surface Area

David A. Noever/ES76 205-544-7783

Since tile discovery of aerogels in the 1980's, many investigators have spec- ulated on gravity limits to producing new varieties of highly porous mate- rials. In biology and chemistry, such large porosity can aid otherwise im- possible enzymatic and catalytic aims. The mathematical ideal (-called FIGURE62.--Cross-sectional view FlouRE63.--Three-dimensional Menger's Sponge) is a solid with of low-gravity solid cutaway of highly infinite surface area and zero vol- produced in a highly rarefied silica solid rarefied form. ume-in essence, a new kind of produced in low gravity. matter (a gelled aerosol) much akin to frozen smoke. If realizable, an such tenuous, taffy-like fibers can solid objects while retaining their essential feature of such a remark- increase markedly in reduced gravity essential vohtme and globular shape. able object would be its highly (-fig. 62). As measured by fractal For other model materials, future textured or spongelike (fractal) prop- dimension, effective surface area flights will investigate further the erties. This roughness on all scales and roughness increased by 40 per- highly textured and fractal nature of gives its mesh of intertwined fibers cent in low gravity. This finding low-gravity assembly. many unusual features: large catalytic supports the conclusion that reliev- activity; low sound and heat conduc- ing internal weight stresses on deli- A detailed mathematical analysis of fractal fibers has been undertaken tance; and, most spectacularly, an cate aggregates can enhance their equivalent surface tension in a solid. overall size (by 2 orders of magni- including predictions for their en- Such fluid-like surface tension alk)ws tude) and internal surface area hanced reactivity, sound and heat the solid to pass reversibly through (fig. 63). damping, surface tension, and pros- tiny orifices while recovering its pects for achieving solid densities less than air. The evidence accullltl- original shape. On Earth, however, That such aggregates can damp heat and sound makes them the large single blocks of such low- lated on tile last flight would indicate highest rated insulators ever pro- density materials collapse, compress, quantitatively that microgravity offers or sag under their own weight duced. Their large surface area a stable prospective environment for makes them uniquely reactive for into condensed pancakes. producing unique examples of such cata[ysis and enzymatic uses. In frozen smoke. On recent KC-135 flights, we sought principle, their density can be re- to demonstrate a key component duced to less than 10 ' parts of solids Noever. DA.. and Nikora,V.l. 1993. of producing higher surface area and hence their intertwined matrix Physics Review Lt,ttetx, submitted _br fractals. Flight paths were selected can exist as a solid that weighs less publication. to give a range of gravity (g) levels: than air. The fluid-like surface ten- Sponsor: Marshall Space Flight Cen- 0.01 g (-low), 0.16 g (lunar), 0.33 g sion of tile material has yet to he ter 1)irector's Discretiona D, Fund (-Martian), 1 g (Earth), and 1.8 g practically applied, but offers one (-high). Results, using the model explanation for how ball lightning [] material of hydrophobic silica, indi- and glow discharges can distort cated that stable agglomeration of around (and seemingly through)

93

Research and Technology 1993 II I I II Avionics

Mass Data Storage Unit board, electrical backplane, built-in Modular Software test function, power supply, and all for Engine Control memory modules have been com- Scott L. Bridge/EB35 pleted for a prototype SSR. Fairchild 205-544-8572 Charles t. Cozelos/EB42 Space Company designed a rugged 205-544-3730 A contract for a solid-state recorder multichip module proven in the Air Force F15 fighter program. Each (SSR) project was started in March The purpose of this project is to module has 50 one-Mb memory 1991. The objective of this project is develop a viable approach, using devices. Design and fabrication of to advance technology to improve Ada TM computer language, to rocket the memory controller and the input/ the availability of space shuttle main engine control software and software output interface circuit boards have engine (SSME) performance data tools that allow the incorporation of been completed, and testing of the acquired during launch and to en- technology developments in sensors, prototype engineering model was hance the data storage capabilities of actuators, connectors, communica- completed Augt, st 1993. NASA for monitoring engine data in tions (i.e., optical bus), and engine high-vibration environments. Tech- A solid-state technology study report control health monitoring techniques. nology used previously does not has been delivered to NASA, and a Also, the project will allow insertion support the data storage require- preliminary design review of the of emerging technologies in the com- ments of future engine health and project was successfully completed puter and electronics fields. This performance monitoring systems and in April 1992. Although the memory design will permit a delta software does not support operation in a capacity of the prototype is 800 Mb verification and elimination of the harsh environment near the SSME. (large enough to fully test and verify periodic end-to-end verification of Unlike a magnetic tape recorder, an the desired design for a space-quali- the SSME, which usually requires SSR is ideal for space flight applica- fied unit), the selected architecture is 5 or 6 mo of labor-intensive effort. tions because it incorporates no readily expandable to 10 Gb. The The design will support flexible and moving parts. prototype has a standard RS-422 modular interfaces. data interface, a Military Standard MSFC has required the SSR developed 1553 data bus, and a high-speed IBM was selected as the implementing under this program to be an all- channel input and output. Users will contractor. In February 1993, at the digital unit in order to interface more be able to play back data faster be- formal kick-off meeting, the Software readily with differing systems on cause the SSR, unlike magnetic tape Management Plan and Development various projects. A widely used Mil- recorders, has the capability to play Plan were reviewed. In June 1993, a itary Standard 1553B data bus has back and record data simultaneously. software architecture review was been incorporated into the design completed. The architecture ap- Sponsor: Office of Advanced to control the recorder, and an ad- proach was accepted, and IBM was Concepts and Technology ditional 1553B bus in the SSR re- given authorization to proceed. ceives data from an engine health Commercial Involvement: monitoring system or another source. Fairchild Space and Defense Co. Sponsor: Office of Advanced Hardware design, fabrication, and Concepts and Technology integration of the microprocessor Commercial Involvement: IBM

96 Technology Programs

Diagnosing the Data I Environmental Control

andMonitoringLife Supportand System I s,0,_ I _ C0mpore ' r Predictionsof NormalOperations Amy N. Cardno/EB43 DiscrepanciesNote I 205-544-3039 i_odel Brandon S. Dewberry/EB43 205-544-4247 Predictionsof Hypotheses The Environmental Control and Life I Generate I Support System (ECLSS) Advanced Automation Project (AAP) is in its Fau_Operations fifth year of developing an intelligent RefuteHypothesis Compare system to monitor and diagnose the Confirmor I space station ECLSS. Model-based diagnosis is the technology chosen FfGURE64.--ECLSS AAP logic flow. by this project to provide fault de- tection and diagnosis of the ECLSS (fig. 64). The model-based reasoning between subsystem and model sen- year, the ECLSS AAP has worked sor values. A fault candidate list is algorithm requires a model of the closely with JSC's Space Station Con- system. It then analyzes this model generated by fault diagnosis proce- trol Center Complex to provide this and automatically detects and diag- dures. Various operations are per- technology. Currently, models of the noses faults. For monitoring the formed on the fault candidate list, carbon dioxide removal assembly system, a graphical user interface is including model inversion, to re- and the temperature and humidity provided that consists of a schematic move suspected components from control system have been developed the candidate list. A candidate list of of the system and critical sensor and are ready to be assessed by the information. one component is declared to be the control center engineers. faulty component. Sponsor: The model consists of complex struc- Space Station Engineering tural and behavioral relationships of The ECLSS AAP is targeting the tech- the subsystem's components. Faults nology toward the space station are detected by noting discrepancies ground support centers. This past

97 Research and Technology 1993

Solid-State Coherent the light's intensity. In addition to rocket launches, shuttle landings, Doppler Udar target range, reflectance, depolariza- advanced warning to airline pilots of tion, vibration spectrum, and other dangerous wind shear and micro- measurements, coherent Doppler bursts, pollution research and source Michael J. Kavaya/EB54 lidar can measure the velocity of the identification, improved targeting for 205-544-8453 target that scattered the detected military ordnance and parachuted light. This is due to the wavelength personnel and supplies, and auto- Most of the scientific measurements shift (Doppler shift) experienced by mobile speed monitoring. The most made by NASA involve remote sens- the reflected light arising from the exciting application of the wind ing. The use of lasers for remote relative motion between the lidar profiling capability is the concept sensing is often the optimum ap- and the target. When the target is of global measurements of wind proach and sometimes the only tech- either air molecules or aerosol par- throughout the troposphere from nique for certain measurements. ticles floating in the air, the lidar an Earth-orbiting lidar (fig. 65). As Light detection and ranging (lidar) measures the wind velocity. These stated in the NASA report referenced will likely progress to become as two targets have sufficient reflec- below, "knowledge of the global useful and beneficial as microwave tance only for the short wavelengths wind field is widely recognized as radio detection and ranging (radar) produced by lasers (versus micro- fundamental to advancing our under- has proven to be. Coherent Doppler wave radar wavelengths). standing and prediction of the total lidar is a subset of lidar that simulta- Earth system," and "the increased use neously provides high sensitivity-- Potential applications of this wind of global wind vector fields in nu- leading to large signal-to-noise velocity profiling capability include merical prediction models offers ratios--and the ability to record and wind profiling for perhaps the greatest potential for utilize the spectral position and shuttle and increased accuracy in operational shape of the returning light, forecasts." and the light's polar- ization properties, as well as

\ SurfaceReturn

aoudReturn

AerosolReturn t"

lm Roundtrip 200Microseconds lime- 3-5 ms

FPGURE65.--Laser Atmospheric Wind Sounder. 98 Technology Programs

OigildSIorogeOs(dloscopeI Cmtinms Wave(CW)Only i osoLO LocalOscifloscope I BolhCWandPulsed Polarization m Mirror Analyzer Beamspl_er o _m I

Helernd_e

Freq.Stability* TemporalProfile Freq._irp* ONPulsed Loser

I PowerEnergyMeter I i,pSpatialProfile) I1w...-.,.,,Analyzer C_puter I

FIGURe66.--Laser characterization facility.

The "heart" of all lidar systems is the This effort is part of a multi-Center and others. The information learned laser. Solid-state lasers are an emerg- program to develop the technology will be shared with the laser devel- ing technology with tremendous and knowledge to enable many opers to allow efficient and optimum potential to eliminate consumables highly desired and long awaited laser development paths, and will be used and to improve the compactness and remote sensing missions. During this at MSFC to permit interpretation of lifetime of lidar systems. These quali- first year, MSFC has defined prelimi- laser performance in a coherent ties are all particularly desirable for nary mission requirements for the Doppler lidar system. In future years, space missions. The goals of this laser and receiver; communicated MSFC plans to develop a companion program are to develop a laser trans- these requirements to Langley Re- detector characterization facility, a search Center (LaRC), where the lidar test-bed facility, a lidar target mitter and receiver for an eyesafe solid-state lasers and one type of calibration facility, and a lidar cali- solid-state coherent Doppler lidar lidar receiver are being developed; bration range. system satisfying the mission require- teamed with JPL in the development ments of an Earth-orbiting wind of a different type of lidar receiver; Curran, RJ., Chair. January 1987. Earth profiler, to develop facilities to test contracted with TRW to more thor- Observing System Instrument Panel candidate lasers and receivers for Report for the Laser Atmospheric oughly define the mission require- Wind Sounder (LAWS), vol. IIg. performance and suitability, to de- ments for the lidar system; and velop a solid-state coherent Doppler begun development of a solid-state Sponsor: Office of Advanced lidar test-bed, to demonstrate laser laser characterization facility at MSFC and receiver performance in the test- (fig. 66). Concepts and Technology bed, to develop a lidar calibration Commercial Involvement: TRW range, and to apply the developed The laser characterization facility will technologies to other missions. be used to test and characterize candidate lasers developed by LaRC

99 Research and Technology 1993

Space Station Module late 1970's. In recognition of the high Currently these agents consist of Power Management and cost of personnel required to operate Maestro that creates and maintains the master schedule from activities Distribution Automated Skylab, the MSFC Astrionics Labora- tory began looking at techniques to created by the user; the front end Subsystem automate power systems. In 1987, load enabler schedule (FELES) that funding became available to take divides the master schedule up into a Bryan K. WalIs/EB72 what had already been learned and form usable by each LLP; the Load 205-544-3311 to push the state of the art in bread- Priority List Management System that board modeling of the electrical creates the load-shed lists for each Norrna DugaI-Whitehead/EB72 205-544-3304 power system in the habitation and LLP; the fault recovery and manage- laboratory modules of the space ment expert system (FRAMES) that The space station module power station. Two contracts for the effort monitors and actively diagnoses management and distribution system were awarded to the Martin Marietta faults in the system, notifying Mae- breadboard is a test-bed demonstrat- Corporation, through whom the stro of the results so rescheduling ing advanced automation techniques current SSM/PMAD system has been can occur; knowledge and negotia- based on a space station module developed. tion tool (KANT), a planner that electrical distribution system. By allows a human user to interact with appropriately distributing computing The power distribution system in the the system as an agent; and the user breadboard consists of two 120-V power from the switch-gear in the interface that apprises the user of the dc buses. They are configured radi- power system up to a central work- system state. These systems all work ally, with power flowing from power station, the system can react immedi- together through the knowledge distribution control units (PDCU's) ately to guarantee safety, while still management and design (KNOMAD) on each bus into three load centers. effectively coordinating actions on a tool. Each load center is powered by each system-wide basis. PMAD functions This highly integrated autonomous such as scheduling/rescheduling, bus so that redundant switching system is a protoWpe for future fault detection and isolation, creation within a load center is possible. The lowest level of switches func- space missions that require low-cost of load-shedding lists, and display of operation of complex systems. The system status are handled by inde- tion as both remotely-controlled switches and as circuit breakers. RPC's and LLP's will have to be de- pendent autonomous agents--sepa- Besides opening due to high current signed into the systems to take full rate programs that work together to like normal circuit breakers, these advantage of the possible benefits, get the job done. A human operator, remote power controllers (RPC's) are but significant savings are possible working with the user interface and also capable of opening due to a by using just those techniques that its associated planner, acts as an- high current over time (I2t), under apply for the system at hand. Current other autonomous agent and is work on the SSM/PMAD breadboard smoothly inte- grated into the whole low voltage, or high temperature. Each RPC also has a built-in current is focused on applying the tech- system. This high level of integration sensor. niques that have been developed and capability makes the SSM/PMAD into the EPS console of JSC's Con- system breadboard a world-class In each load center and PDCU is a solidated Control Center, which will example of cutting-edge automation lowest level processor (LLP). The LLP operate both the space station and techniques. monitors the switches and adminis- shuttle. The approaches and techniques ters the local portions of the master proved in the SSM/PMAD system are schedule. It opens or closes switches Sponsor: Office of Advanced now being integrated into the electri- according to the schedule, monitors Concepts and Technology switch currents to make sure they cal power system console software Commercial Involvement: Martin for the JSC Consolidated Control are within scheduled limits, and Marietta Corporation; Synbiotics, Center. Developed in cooperation sheds loads that are not. In case of a Inc.; and Micon Engineering with the LeRC, as well as controllers fault, the LLP will handle redundant at KSC, an EPS console using these switching, if necessary, and can shed University Involvement: University technologies is expected to enable loads, starting with the least impor- of Alabama in Huntsville, University better, less expensive operations tant loads, by using its load-shed list. of Central Florida, Florida Institute of than current techniques. The other segments of control and Technology, and University of Ten- nessee Space Institute The SSM/PMAD system is an out- protection in the SSM/PMAD system growth of work begun back in the are called autonomous agents.

1O0 Technology Programs

Materials and Manufacturing Processes IIII I II

Hybrid Capacitive- • CoatingS(0.023inaverage) Inductive Microsensor [] Coating4 (0.018inaverage) [] Coating3 (0.014inaverage) Arrays for Evaluating I_1 CoGfing2 (0.011inaverage) the Integrity of Thermal [] Coating1(0.010inaverage) Barrier Coatings

SamuelS. Russell/EH13 205-544-4411 800-

ShakeelS. Razvi/CQ05 760- 205-544-7377 120-

The consistency of thermal coatings "_ 680- on turbine blades and other gas £ turbine components is important in 640- the prevention of oxidation, corro- sion, and erosion of these compo- 600- nents. This SBIR effort seeks the simultaneous detection of coating bond, porosity, and thickness through hybrid electrical test meth- ods. A novel hybrid sensor array was FIGURE67.--Three-dimensional column chart showing inductance measured designed and built using thin film over coatings varying in thickness between 0.025-0.050 in. technologies that fuse the capacitive and inductive sensing methodologies 6.3 into a single sensor design. The sensors were sputtered on dielectric 6.2 substrates and may be miniaturized c_Estimate 6.1 l' o:o0'o'nl for application. The design was opti- mized by using a finite element L 6.0 model of the electrical response due e, to anomalies in thermal protective .m 5.9 coatings. K ,5 5.8

5.7 A series of tests were conducted to Eli % [] optimize the use of this sensor with 5.6 standard eddy current instrumenta- tion over a frequency range of 100 Hz 5.5 I I I 1 I I I I 0 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0,045 to 10 MHz. Inconel plates were coated with zirconium oxide, 8 per- Thinckness/Permittivity cent yttrium oxide, of differing thick- nesses and porosities to simulate F_GURE68.--Measured capacitance plotted against thickness/permittivity coating variations on high-tempera- of thermal barrier coatings at locations shown above. Sensor ture turbomachine W. Figures 67 and lift-off (LO)--O.010 in. 68 show changes in the inductance and capacitance of the sensor ele- Further development of these sensors Sponsor: Office of Advanced ments plotted against different coat- and sensor arrays, and their subse- Concepts and Technology. Small ing thicknesses and permittivities. quent integration into an automated Business Innovation Research Experiments revealed that the sensor inspection system for therma[ barrier Program is sensitive to changes in coating coating characterization, is under thickness of 0.001 in or smaller and consideration. An SBIR Phase II con- porosities on the order of S percent. tract for this effort is anticipated.

101 Research and Technology 1993

Formability Study 3.38in of Aerospace Aluminum Alloys

George E. Wertz/EH 15 205-544-2663

The space station module walls are being fabricated of 2219 aluminum. Early tests performed to evaluate the performance of 2219-T87 versus 2.00in 5456-H116 aluminum relative to micrometeoroid and orbital debris impact damage were inconclusive, in that no significant difference was measured from hypervelocity impact tests. Therefore, the aluminum alloy 2219-T87 was selected for the mod- OriginalDesign Modified Design ule walls based on other criteria. In order to gain a better understanding FIGURE69.--Formability test fixture. of the relationship between hyper- velocity impact damage and different The specimens are photographically plots the two principal surface strains in the sheet over those combinations alloys of aluminum, additional stud- printed with a circle-grid pattern ies were initiated incorporating hy- using a photosensitive-resist method. of strain where thinning occurs. Any combination of the two surface pervelocity penetration mechanics The circle diameter is important in models. These models use material measuring the deformations accu- strains falling below the forming- forming-limit data to help establish rately and must be small in relation limit curve is considered acceptable. the material fracture criteria. to the strain gradient in the speci- Any combination falling above it will men. Once the material is deformed, produce a failure. the original circles will appear ellipti- The technique used to investigate The attached experimental data have cal near the fracture point. The per- the forming-limits of materials in- been obtained for aluminum alloys cent change in shape on the long volves biaxial punch stretch testing 2219-T87 and 5456-Hl16 using a side is major strain (always positive of sheet metal specimens clamped standard technique, but with a modi- and larger than the original circle) securely between two die plates at fied test fixture. Since the alloys and the percent change on the short the periphery. In this test, the strains side is minor strain (can be either under investigation are tempered for in a specimen vary over the stretched ultimate strength, the standard holder larger or smaller and, therefore, dome from a strain state near plane caused premature failure at the hold- positive or negative). strain near the flange to one approxi- down bead. In order to prevent this mating balanced biaxial tension at The material under examination is premature failure, the fixture (fig. 69) the pole. The use of lubrication made to thin over a range of strain was prepared along with appropriate makes the strain ratio at fracture ratios to its failure point. Failure is material specimens. Successful tests more biaxial as the flow localization defined as the appearance of local- are being performed using this modi- and failure occur near the flange ized thinning or necking, and not fied test fixture. The experimental when poorly lubricated and at the necessarily final separation of the data for 2219-T87 and 5456-Hl16 pole when good lubrication is uti- material. These failure/nonfailure are plotted as a forming-limit dia- lized. The strain paths and failure data can be represented graphically gram (fig. 70) for indicating a strains are measured through the as forming-limit diagrams against material's forming strain. At any prior application of grids onto the which forming strains can be com- single point on the material, the test specimens. pared. This forming-limit diagram forming strain equals the metal's

102 Technology Programs

30

.--. 25 .B e FrodureEffeded J o AcceptableFradure ._ 2o • # o _ e_ _4"- g

•_ 15 o _ _ e o o _/ Q o • o • _o _ eeP/ E ]0

0 e o e I a. 5 e o o o_ S_8 o o o o o o 0 I I l I -I0 -5 0 5 10 15 20 Percentageof Minor Strain

3O # # #

.Ii 25 I e FractureEffeded # # e # #J m #o FractureAcceptable # # # e # .. e e . e: @e/_e _ 2a e ' . # . ee o_ "_ 15 e ee@_ e # e# o o_ ,,'_ o o% oo oeo o o 0

_' ego 0 _ 0 o m. 5

0 I I I I -10 -5 O S 10 15 20 Percentageof Minor Strain

F_GURE70.--Forming limit curve 2219-T87 (top) and forming limit curve 5456-H 116 (bottom).

ultimate capacity to be worked or will produce failure. Forming-limit hypervelocity impacts from micro- deformed. This point is said to be data may characterize the potential meteoroids and orbital debris on the metal's forming limits. Exceeding performance of aluminum alloys space structures. this limit will tear the material. proposed as space station module wall materials. These strain-based Spoaso_ Space Stadon Pmiects Office The concept of this forming-limit failure criteria will be imposed in the diagram is useful in predicting development of hydrocodes to simu- when given strains in a material late the deformation processes of

103 Research and Technology 1993

Long Duration Exposure thermal vacuum, and meteoroid/ measurements of the surfaces of Facility Experiments and orbital debris impact. Atomic oxygen flight samples are being analyzed. attack of bulk metals is being evalu- Trend analysis based on spectral Space Environment ated through various techniques, band dependence is in progress and Effects on Materials including ellipsometry, changes in will be completed for presentation Studies optical properties, and electron scan- at the LDEF Third Post-Retrieval ning analysis (ESCA). Effects of the Symposium in November 1993. Miria M. Finckenor/EH 15 space environment on polymeric 205-544-9244 material performance are also being studied. Analysis includes differential MSFC, in cooperation with the Roger C. Linton/EH15 University of Alabama in Huntsville, 205-544-2526 scanning calorimetry, differential thermal analysis, and thermogravi- the Alabama Space Grant Consor- Ann F. Whitaker/EH41 metric analysis on polymeric flight tium, and the Socie W for Manu- 205-544-2510 and control samples. facturing and Process Engineering (SAMPE), held the LDEF Materials The Long Duration Exposure Facility Results for Spacecraft Applications Experiment A0034 consisted of two data base of space environmental Conference on October 27-28, 1993. effects on materials continues to modules, exposing selected thermal More than 250 attendees toured the control materials to LDEF leading provide valuable information for MSFC facilities and heard presenta- and trailing edge conditions. Current designing long-term mission space- tions on the spacecraft environment, studies include laboratory exposure craft. The three LDEF experiments atomic oxygen erosion and ultravio- testing of thermal control coatings, currently being analyzed are the let radiation damage, composites and including selected flight samples, to Solar Array Material Passive LDEF other structural materials, thermal determine specific effects and influ- Experiment A0171, the Atomic control materials, and optical materi- ences of atomic oxygen and ultravio- Oxygen Stimulated Outgassing Ex- als, as well as plenary sessions on let radiation. Optical witness samples periment A0034, and the Thermal future space exploration. are being evaluated for deposition of Control Surfaces Experiment S0069. outgassing products, with results Materials being evaluated include correlated to the performance of the polymers, metals, composites, ther- Sponsor: Office of Advanced adjacent coating. mal control coatings, dielectric films, Concepts and Technology and solar cells. Experiment S0069 studies have in- Experiment A0171 passively exposed cluded remeasuring optical proper- University Involvement: University of Alabama in Huntsville a variety of materials to the ram ties of flight samples to study the (leading edge) environment of effect of long-term ground storage. atomic oxygen, ultraviolet radiation, Fourier Transform Infrared (FTIR)

104 Technology Programs

Novel Material Concepts evaluation of advanced material shield applications. The analysis for Spacecraft Debris concepts for a wide range of impact model resulting from the Phase I conditions. research effort has established the engineering design guidelines and Angela M. Nolen/EH 15 Technology Development Associa- 205-544-9245 techniques for developing optimal tion, Inc. (TDA) has addressed these fabric material systems that provide James M. Zwiener/EH 15 issues this year in a Phase 1 SBIR improved spacecraft protection for a 205-544-2528 program. The primary objective of wide range of particle sizes, impact this program is the development of angles, and velocities. The design and operation of space- novel fabric material concepts that craft must give serious consideration offer lightweight and improved de- to the space debris environment and bris protection compared with the This research program offers signifi- its effect on mission performance. conventional dual-plate aluminum cant benefits for future spacecraft Hypervelocity impacts by orbital shielding. The debris shielding con- that must be designed to operate debris particles can cause severe cepts identified by TDA as a result in an orbital debris environment. damage to vital spacecraft systems of the Phase I program include a The Phase I program has laid the and components, resulting in com- multilayer, functionally gradient necessary groundwork for further ponent degradation, catastrophic fabric and a 3-D flexible sandwich development and experimentation in structural failure, or injury to crew core fabric geometry. These concepts Phase II. Several candidate function- members. Conventional dual-plate are unique in that they combine the ally gradient fabric material configu- aluminum bumper/pressure wall beneficial shield material properties rations, as well as a 3-I) sandwich shields, originally developed to pro- and geometry in order to achieve the core fabric concept, have been rec- vide spacecraft protection against the desired functionality, while offering ommended for t\lrther development and evaluation. natural micrometeoroid hazard, will improved weight and volume efti- result in significant weight penalties ciency. These concepts also provide when designed to protect spacecraft the abili W to tailor the constituent Sponsor: Office of Advanced against a continuously increasing materials and geometry in order to Concepts and Technology, Small orbital debris environment. More provide protection against a wide Business Innovation Research efficient orbital debris shield designs range of debris impact conditions Program are urgently needed to provide im- (i.e., projectile density, size, and proved protection and lower weight impact velocity). A significant feature for future spacecraft missions. Im- of the program is the development Commercial Involvement: Tech- provements in analytical modeling of a numerical analysis model for the nology Development Association, Inc. capability are also required to allow design, evaluation, and optimization for more cost-effective design and of flexible fabric materials or debris

105 Research and Technology 1993

Approximation ISO,O00_R Techniques to Determine the Increase in Surface I00,000 Area Due to Surface 50,000 Roughness 0 David L. Edwards/EH 15 205 -544 -4081 -50,OOO

The soluble core of future large solid -I00,000 rocket motors may utilize a conduc- tive/waterproof barrier to form the -150,000 initial propellant surface. Techniques SpraySurface m for applying the conductive/water- I I I I I I I I I 0 2 4 6 8 10 12 14 16 18 20 proof barrier to the soluble core are brush, spray, and molded applica- tions. The increased surface area 30,000 created by some of these applica- 20,000 tions may have a potentially adverse 10,000 effect on the initial pressure spike during ignition of the solid rocket 0 motor. This technique provides a -20,000 method to approximate the increase ._ -30,OOO in surface area due to surface roughness. -40,OOO -50,000 Three samples--identified as brush, -60,000 spray, and molded--are measured using a Dektak II surface profiler. -70,000 This instrument utilizes a stylus that measures surface structure over a 0 2 4 6 8 I0 12 14 16 IB 20 preset length. Figure 71 shows the scans obtained from the Dektak II. R Although these scans indicate a ran- 300,000 dom surface roughness, approxima- tions can be made to make the 200,000 roughness a periodic function. The approximations utilized were the tri- 100,000 angular wave approximation (TWA), conic section wave approximation 0 (CSWA), and the rectangular wave approximation (RWA). The investi- -100,000 gator must examine the scans and -200,000 ) approximate the average amplitude and period of the funtion. These -3OO,000 BrushSurface values will be used in the TWA, CSWA, and RWA approximation L I I I J I I I I 0 2 4 6 8 10 12 14 16 18 20 techniques. ScanDistance(pro)

FIGURE71.--Dektak II scan of spray, molded, and brush surfaces.

106 Technology Programs

TABLE4.--Percentage increase in surface area for coatings

Coatinc TWA CSWA RWA

0.009999% 0.045500% 1.97% I : Period -_l Spray RWA Molded 0.005625% 0.001295% 1.48%

Brush 2.164700% 2.870000% 24.22%

Amplitude_[__

get an area, then comparing to a Application of this technique for tile perfectly flat surface, will yield a soluble core coatings shows that the CSWA change in surface area. molded coating application is the smoothest surface, with the spray The CSWA technique uses the period coating providing a slightly rougher as the chord of a circle and the am- surface. The brush coating is 2 and 3 plitude as the distance from the cen- orders of magnitude rougher than Amplitude ter of the chord to the circle. Using the spray and molded coatings, re- _L these values, the arc length ( { ) can spectively. Table 4 summarizes the Period be determined. As with the TWA, percentage increase in surface area the area _ X _ is calculated and for the various coatings using these TWA compared to a fiat surface to deter- techniques. mine the change in surface area. FIGURE 72.--Wave approximation The RWA uses the period as one Sponsor: Office of Space Systems techniques. side of a rectangle and the ampli- Development tude as the other side. The equation Figure 72 shows the various wave for determining the length ( _ ) is: approximation techniques used in =2 (amplitude)+period. Once this work. The TWA utilizes the has been determined, the area can Pythagorean theorem given by be calculated as in the TWA and Q =(x 2 + y2) _'_2for the increased CSWA, then compared to a fiat sur- length over one-half of the period in face to determine the change in one direction. Multiplying Q × _ to surface area.

107 Research and Technology 1993

Optical Effects Facility Three solar-blind photomultiplier Beam Processing of detectors positioned at specular and NARIoy-Z for Improved forward- and back-scattering angles Roger C. Linton/EH 15 Microstructure, 205-544-2526 from the optical collectors provide a measure of the bidirectional reflec- Properties, and Life Enhancement of Main Molecular film contamination depos- tance distribution function (BRDF) Combustion Chamber ited on and degrading the perfor- from molecularly contaminated op- mance of critical optical surfaces, tics at vacuum UV wavelengths. For Liner whether in space or in ground-based purposes of normalization of signal, the intensity of the krypton micro- testing, can be sensitive to the effects Biliyar N. Bhat/EH23 of repressurization, atmospheric wave-excited resonance lamp used 205-544-2596 as the illumination source is moni- exposure, and subsequent depressur- tored by a fourth detector at the ization (when required). Therefore, Efforts are under way to improve the vacuum chamber entrance aperture. for the most accurate analysis of the space shuttle main engine life of the effects of contamination deposited in The principal emission of this kryp- main combustion chamber (MCC). ton source includes the characteristic a vacuum on optical surfaces, mea- The MCC life is limited by the life of krypton resonance lines at 116.5 and surements of the thickness and the its liner, currently made from a cop- 123.6 nm. optical effects should be performed per (Cu)-based alloy, wrought in situ, that is, in the environment in NARIoy-Z (Cu, 3 weight percent This facility provides a more compre- which it will be used. The in situ silver (Ag), 0.5 weight percent zirco- hensive investigation of the effects contamination effects facility in the nium (Zr)), which is degraded in the of contamination on optical sur- MSFC Materials and Processes Labo- engine operating environment. The faces by experimentally relating the ratory provides this capability for microstructure is changed with grain observed optical degradation to optical witness samples exposed in boundary precipitations and migra- molecular contamination growth kin- vacuum to heated materials with tion of vacancies to grain bound- etics for correlation with analytical actively monitored data from tem- aries, forming voids that often result modeling. Recent testing with candi- perature-controlled quartz crystal in grain boundary separation. These date silicone seal materials (SSF) and microbalances (TQCM's) and four microstructural changes result in Hysol TM adhesive have indicated a vacuum ultraviolet (UV) wavelength lower mechanical properties, espe- significant difference in effects de- optical signal detectors. This facility cially lower ductility at operating pendent on the inherent optical is providing data for candidate space temperatures (-550 °C). This has led materials, relating the optical effects constants of the optical witness to formation of cracks in the MCC samples. of deposited contamination on opti- liner. Additionally, vacuum plasma cal witness samples as a function of spraying (VPS) of NARIoy-Z has time, source material temperature, Sponsor: Office of Advanced been used to form MCC liners as and witness sample temperature; Concepts and Technology a low-cost alternative to the cur- correlating the measured thickness rent process. Unfortunately, VPS growth in real time with TQCM's; Unive_lty Involvement= University NARIoy-Z also tends to have a non- of Alabama in Huntsville and analyzing the evolved molecular uniform microstructure containing species with a residual gas analyzer voids and grain boundary precipi- (RGA). tates similar to the degraded wrought NARIoy-Z. The present research effort is directed toward

108 Technology Programs

restoration of NARloy-Z microstruc- of Tennessee Space Institute (UTSI). ture through beam processing that The preliminary laser glazing work will enhance the life of the liner. was done at U of I. Laser glazing of This process is applicable to both NAPdoy-Z test specimens is being wrought (degraded) and VPS MCC done at Penn State; these specimens . , I' liners and is expected to produce will be used to generate a mechani- microstructure, mechanical, and .' .. ."..., _;_ ..., .... ., ;., cal property data base. Electron thermal properties equivalent to or beam glazing and material character- better than conventional wrought ization are being done in-house by NARIoy-Z. Dr. J. Singh, a senior National Re- search Council Fellow working in the Materials and Processes Labora- Initially, the feasibility of beam pro- I_lLg ? tory. UTSI will assist in developing cessing was demonstrated with VPS laser glazing parameters for the NARloy-Z specimens that had non- SSME MCC liner. uniform microstructures containing cavities, voids, and grain boundary In summary, laser and electron precipitates similar to the microstruc- ,. . • -'i ture of the SSME MCC liner after hot beam processing has been used successfully to restore and improve firing. Both electron and laser beams NARIoy-Z microstructure. These were used for the feasibility study, processes look promising for en- which consisted of glazing the sur- hancing the life of the SSME MCC face of NARIoy-Z to a depth of 0.25 F_ur_ 73.--Optical la) and scan- liner. Periodic laser glazing of the to 1.25 mm and examining the mi- ning electron (b) micro hot wall of the wrought NARIoy-Z crostructure optically and in a scan- graphs of VPS NARIoy-Z liner will restore the original micro- ning electron microscope. The showing dramatic miers- structure, prevent crack formation, glazed areas showed a very uni- structural improvement in and, hence, could extend the life of form distribution of fine precipitates a laser-glazed surface the liner indefinitely. throughout the matrix (fig. 73). The ILGS). grain size was much finer, which enhances mechanical properties, Sponsors: Office of Advanced generated for the laser-glazed especially ductility. No grain bound- Concepts and Technology, and NARIoy-Z. A patent application has ary precipitation was observed. Cavi- Office of Space Flight also been made on this process. ties and voids were eliminated. Both Commercial Involvement: laser and electron beam glazing produced similar, uniform micro- It is planned to use the beam pro- Rocketdyne, A Division of Rockwell International structures in the wrought alloy. Due cesses to enhance the life of the to inherent rapid melting and solidi- SSME MCC liner. This is a joint pro- University Involvement: University fication that occur during glazing, gram with Rockwell International, of Illinois, Pennsylvania State Univer- solid solubility of the solute atoms Rocketdyne Division, with participa- sity, and University of Tennessee Ag and Zr in the matrix is extended tion from three universities: the Uni- and, hence, hardness and strength versity of Illinois, Urbana-Champaign Space Institute of the alloy are improved. A me- (U of I); Pennsylvania State Univer- chanical property data base is being sity (Penn State); and the University

109 Research and Technology 1993

Vacuum Welding and welding technique has been devel- Brazing for Space oped in which argon gas is supplied through a hollow electrode. Welding Applications torches and electrode designs have been developed for vacuum welding. Richard M. Poorman/EH25 With these tools, numerous vacuum 205-544-1986 welds and weld overlays have been made in vacuum chambers at MSFC. Interest in vacuum welding at MSFC is related to development of space The vacuum welds show some welding fabrication and repair capa- unique characteristics. Fluidity and bilities. Expanding these welding and wetting action of the weld pool are brazing capabilities is essential to greatly enhanced. Welding pools of meet NASA's space exploration goals. Inconel 718 TM and Incoloy 903 TM are The primary developments described noted for their sluggish flow and FIGURE74.--Manual welding in low here are oriented to processes and lack of wetting. However, weld pools gravity on the KC-135 materials. of these alloys in a vacuum are very aircraft. fluid and blend smoothly at the Initial welding and brazing experi- weld's liquid/solid surface. This en- Processes other than GTAW are also ments by MSFC were done on hances the performance of the weld. being evaluated for space welding Skylab in 1973. These were electron Pool fluidity and blend of weld nug- applications. They include plasma beam (EB) welds on aluminum, get are very desirable weld charac- arc, gas metal arc, and electron stainless steel, and tantalum. The teristics that reduce the notch effects beam. braze joints were on stainless steel and stress risers in the weld zone. tube couplings. All experiments were Cracking is also a common problem Poorman, R.M. June 1991. Vacuum Vapor successful and pointed to the fact in weld overlays of Inconel 903 TM on Deposition--A Spinoff of Space that gravity has only a minor effect Inconei 718 TM. Vacuum weld tests Welding Development. NASA on welding or brazing such joints. have shown less tendency to form TM-103542. Surface tension drives the metal cracks than conventional welding flow. The presence or absence of a processes in atmosphere. Russell, C.K.; Poorman, R.M.; Jones, c.s.; vacuum may dictate the process to and Nunes, A.C. IIl. October 21-24, be used in space welding. Extensive weld studies of GTAW at 1991. Considerations of Metal various gravity levels have been Joining Processes for Space Fabrica- The current effort has been directed conducted. Both automated and tion, Construction, and Repair. SAMPE 23d International Technical manual welds were made in low- at gas tungsten arc welding (GTAW). Conference. This includes welding in both va- gravity aboard a KC-135 aircraft. All cuum and one-atmosphere environ- were made in a gaseous environ- United States Patent 5,149,932--Arc/Gas ments. The GTAW process, operated ment of one atmosphere. The gravity Electrode---September 22, 1992. in a one-atmosphere environment, is level does not produce any unex- Inventors: Richard M. Poorman and well established. However, GTAW pected changes. Minor changes in Jack Weeks. welding in a vacuum will require microstructure were observed. Mate- development work. rials welded were aluminum, 304L Sponsors: Office of Advanced and 347 stainless steel, and Inconel Concepts and Technology, and Office of Space Flight A welding arc requires the presence 718 TM. No significant mechanical of ionized material within the arc to properties changes have been associ- carry the welding current. A vacuum ated with gravity levels (fig. 74).

110 Technology Programs

Forming of Aluminum- Lithium and High Aspect Ratio Orthogrid Panels

Benny F. Graham/EH25 205-544-4808

Recent advances in aluminum- lithium alloys have made them more attractive for potential use in cryo- genic tank applications. As a result, advanced forming and manufacturing methods need to be developed in order to use these alloys effectively.

In the past, methods used to shape lightweight stiffened structural com- FIGURE75.--Prototype aluminum-lithium alloy 2195 roll-formed panel. ponents made from aluminum have been "bump" forming on a hydraulic external tank (ET) radius (fig. 75) by was machined at MSFC and roll press brake and high-temperature both "bump" and "roll" forming formed using a protective cover restraint ("age") forming. With methods. Aluminum alloy 2219 was plate on the stiffening ribs. This strength-to-weight ratios becoming used in order to compare both pro- prototype test panel showed negli- increasingly more critical, complex cesses with a well-known alloy. gible "coining" on the ribs and an lightweight rib-stiffened structural Results showed incremental "coin- improvement in anticlastic curvature forms of this alloy, such as orthogrid ing" on the stiffening ribs for the (fig. 75). Further investigations seek panels, will require advances in bump-formed panel and continuous to establish age-forming characteris- forming techniques in order to en- "coining" on the stiffening ribs on tics and identify the most effective sure both structural integrity and the roll-formed panel. A third panel processes to achieve acceptable cost-effective producibility. Prelimi- with varying rib aspect ratios was panels for cryogenic tankage and nary results from "roll" forming roll formed using a protective cover other applications. orthogrid test panels at MSFC are plate on the stiffening ribs and promising. More development is showed almost no "coining" on the $1_rtsor,a: Office of Space Flight, needed to quantify results and evalu- ribs. A fourth panel with higher stiff- and Office of Space Systems Devel- ate factors such as curvature and ening rib aspect ratios was roll opment radial surface conformity and stiffen- formed without a protective cover ing rib aspect ratios. In order to meet sheet and produced rib buckling on dimensional requirements, age form- the higher rib aspect ratios. These ing also will likely be part of the third and fourth panels also estab- final processing sequence. lished an aspect ratio forming limit. Forming development on orthogrid All of the panels revealed some cur- panels at MSFC began by machining vature variations. A fifth panel made and forming these panels to the from aluminum-lithium alloy 2195

111 Research and Technology 1993

New Weld Controller Incorporating some of the newest Thermal Spray Forming Nearing Completion, off-the-shelf technologies, the new of Refractory Sample weld pendant, developed at MSFC, and Welding Pendant Ampoule Cartridges has been designed to be robust, Incorporates New flexible, and tied to accepted indus- for Single Crystal Growth Technologies try standards. The pendant control Space Furnaces hardware is made up of local operat- Kirby G. Lawless/EH25 ing network (LON) neuron chips, Frank R. Zimmerman/EH25 205-544-2821 which are each programmable mi- 205-544-4958 croprocessors with built-in support Richard M. Poorman/EH25 for many communication and data Computer-controlled variable polarity 205-544-1986 plasma arc (VPPA) welding has been acquisitions. Because the chip is programmable, less demand will be used in the production of the space A thermal spray process is being placed on the weld controller pro- shuttle ET since 1983. This welding used to build up refractory metals system provides control of the criti- cessor for handling operator inter- and ceramics into a containment face. In addition, a programmable cal welding parameters, in addition cartridge for high-temperature, gas plasma display is being incorpo- to providing historical documenta- single-crystal semiconductor growth rated for flexible use as a text or tion of programmed and actual weld- experiments. This process uses high- graphics screen. These displays were ing parameters for all welds. energy plasma inside a low-pressure originally targeted at the military for (100--200 torr) inert environment to A new welding control computer has jet fighter cockpit displays, and are been defined as a UNiX-based con- apply layers of material onto a re- durable and robust enough for the movable mandrel. A variety of mate- troller able to integrate various sen- factory environment. The result is a rials are being characterized and sor processing and multiple axes of pendant that can be configured to evaluated against a demanding set of motion. It is projected that the first accommodate emerging process requirements, including high service major integration efforts for this con- control technologies, without long temperature (up to 1,600 °C), oxida- troller will include vision sensor development periods, Incorporation tion resistance, and resistance to processing, automated wire position- of the new controller into ET pro- liquid metal attack. Techniques to ing, and weld model calculations duction welding is targeted for fiscal spray form refractory metals (tung- based on sensor feedback. Two year 1995. versions of the advanced weld con- sten, molybdenum, niobium, tanta- lum) and ceramics (alumina, boron troller have recently been accepted Sponsor: Office of Space Flight through factory delivery testing. nitride) are being developed in the plasma spray cell at MSFC.

NASA's Crystal Growth Furnace (CGF) has flown on the USML-1 Spacelab mission to conduct single- crystal growth work on a variety of semiconductor materials. These semi- conductor crystals (gallium arsenide (Ga-As), cadmium zinc telluride (Cd-An-Te), mercurous zinc telluride (Hg-Zn-Te), mercurous cadmium telluride (Hg-Cd-Te)) are grown in quartz ampoules surrounded by insulation, thermocouples, and other instrumentation. The entire experi- ment is contained within a sample ampoule cartridge (SAC) (fig. 76) that facilitates handling and installa- tion into the furnace. The SAC also

112 Technology Programs

functions as a containment system, inert atmosphere within a vacuum Thermocouple/.--I which is required to protect the flight chan_ber. Plasma is generated by crew" from the highly toxic materials passing an inert gas through a dc used in these crystal growth experi- arc'. The gas is ionized, and the re- ments. If the ampoule containing the sulting high-temperature plasma EndCop_ crystal growth material should rup- exits through a nozzle into the ture, these cartridges provide a nec- low-pressure (nominally essary level of containment. The 100 torr) environment. Connedor_ containment requirement is compli- cated by the fact that most of these crystal growth compounds are Spdng known to aggressively attack \ SpringRetainer most common structural metals at furnace QuartzTube operating tem- peratures. UpperAmpouleSupport

QuartzWool (MSFC/GCRC/I_PIOnly)

LowerAmpouleSupport

$0mpleAmpouleCorlridge

FIGURE76.--CGF cartridge exploded view.

Currently, these cartridges are made The material to be deposited is wall structures 0.64 to 0.76 mm. of materials that are attacked at a injected into the plasma plume as a Ceramic (alumina, boron nitride, rate that will not fully penetrate the fine powder, heated, and accelerated silica) coatings will be used to pro- cartridge within the duration of the toward the substrate to be coated. tect the metal from high-temperature experiment. For experiments of To form containment cartridges, a oxidation and liquid semiconductor longer duration, a more chemically combination of materials will be attack, if needed. resistant material is required to en- deposited in layers on a removable sure that no breach in the contain- mandrel. During VPS forming, the The fabrication sequence to form ment will occur. Regardless of the mandrel functions as a male mold, these cartridges will incorporate up material used, the current manufac- with the outer contour of the man- to three layers of material in a mono- turing sequence is labor intensive, drel forming the inside contour of lithic structure. Each of these layers dependent upon product availabili W, the sprayed deposit. will be deposited on a removable and contains several fabrication steps mandrel using the VPS process and joining processes. The service temperature of these (fig. 77). The first layer sprayed will cartridges will range from 1,100 to form the inside surface of the car- To address these issues of chemical 1,600 °C. Several refractory metals tridge. Its function is to comain the inertness and manufacturing, MSFC's and ceramics are being considered liquid crystal growth material should Materials and Processes Laboratory to accommodate these high tempera- the ampoule rupture. Ceramics such has undertaken an effort to form the tures. The metals (tungsten (W), as alumina and boron nitride are SAC using the vacuum plasma spray niobium (Nb), molybdenum (Mo), inerl to many of the semiconductor process. VPS is a thermal spray pro- and tantalum (TaD provide structural materials used in these experiments. cess conducted in a low-pressure, strength and toughness for these thin While providing excellent chemical

113 Research and Technology 1993

New Direction in Phthalocyanine Pigments

Diep V. Trinh/EH32 205-544-6797

Phthalocyanines have been used as pigments in coatings and related applications for many years. These pigments are some of the most stable organic pigments known. The phthalo blue and green pigments have been shown to be UV stable and thermally stable to over 400 °C. These phthalocyanines are both a semiconductor and photoconductor, exhibiting catalytic activity and photostabilization capability of poly- mers. Many metal-free and metallic phthalocyanine derivatives have been prepared. The new classes of phthalocyanine pigments could be used as coatings on NASA spacecraft material such as glass to decrease the FICURE77.--Vacuum plasma spray deposition of refractory optical degradation from UV light material onto removable mandrel. and as a coating on solar cells to increase lifetime and efficiency. resistance, ceramics are too brittle to material. Leak- and burst-testing have sufficient handling strength in were also performed to qualify the The synthesis of the single-ringed the thickness range of interest. A VPS process parameters. phthalocyanine based on 1,2 dido- second layer of refractory metal will decyloxy-4,5 dicyanobenzene be sprayed to provide bulk structural The VPS forming process allows the (fig. 78) and bisphthalocyanine strength to the thin wall cartridge for selection of materials based on their based upon a naphthalene core, room-temperature handling and desirable properties. Consequently, have been completed. These com- high-temperature operation. The each sample ampoule cartridge can pounds have been purified. The third layer is an oxidation-resistant be designed for a specific application characterization of the single-ring material (probably ceramic) to pro- and set of requirements, with few and double-ring compound by tect the underlying refractory metal restrictions imposed by the manufac- UV/visible, Fourier transform infra- from high-temperature oxidation. turing process. red, nuclear magnetic resonance Several full-sized test articles have (NMR), x-ray diffraction, and mass been spray formed with multiple Sponsors: Payload Projects Office, spectroscopy were completed. layers. Metallographic examination MSFC; and Microgravity Science The successful synthesis of the key verified the proper thickness of each and Applications Division, NASA 1,8-naphthalene intermediate com- layer and the microstructure of each Headquarters pound (fig. 79) led to a new and unique class of phthalocyanine. The first example of its type and the first amine/imine tautomer to be isolated is 1,8-napthalene. The proton and carbon-13 NMR's illustrate that this compound does not tautomerize rapidly on an NMR time scale as has been proposed previously in literature. 114 Technology Programs

R4 R4 and interpreted results were found I RI = R2 = Phenyl R3 = R4 = H that would not have been possible R3 without molecular modeling or "2 R, R2 Phefly| R 3 R4* C' R3___" "'_ synthetic results. / I

R4 The evaluation of phthalocyanine for protecting plastic (in this case, R 3 R2 H_ R2 polystyrene) from UV damage has been conducted. Samples of polysty- rene with no inhibitor, 3-percent phthalo blue (commercial) and 3-per- R2 H R2 cent phthalo green (commercial), R2 H R2 respectively, were prepared. These will serve as standards for compari- son with the newly synthesized pig- RI N- \N/-N R ments. The sample and reference material have been tested for ten- sile strength, gloss, color, and R4 R4 1 N ..._._N/_/._N KI change within the IR spectra after Phthalocyanine exposure to UV light. The polymer undergoes photodegradation by R3_ R3 photopolymerization and cross-link- R4 R4 ing without oxygen. The newly syn- Bisphthalocyanine thesized pigments decreased the photopolymerization process of poly- FIGURE78.--Phthalocyanine and bisphthalocyanine. styrene approximately 66 percent.

$Donsor: Marshall Space Flight HH2 The isolation of a green, stable new compound based upon 1,8-naphtha- Center Director's Discretionary Fund lene is the first of its type to be syn- thesized. It represents a new series of chemicals that may possess (, unique catalytic, conductive, or photochemical properties.

The work on these structures repre- sents several breakthroughs and firsts. The integral use of molecular modeling, including quantum me- chanics with synthesis, has proven that the combination is the best ap- FIGURE79.--Compound proach to technological advancement 1,8-naphthalene. in this area. Barriers, table targets,

115 Research and Technology 1993

Environmental 2o0_ ,e. 38O Replacement Technology: _ 18o ,,"...... 36O 16o 340 _ Aqueous Cleaners, 140I- _ - ',._"_ 320

Primers, and Adhesives _ ]20 ,, 300 280 for SRM Cases _ loo80 ,, 268 _ M. Louise Semmel/EH33 _I_ 60 I _ ButtonII "a 240 205-544-3650 _ 40 I--_'-- Peel I -"" 2O 220 The production of ozone depleting 0 1 I I , I I 2OO 0 50 100 150 200 2SO 3O0 substances, such as chlorinated solvents routinely present in clean- Contaminati_ Level, rag/it 2 ers, primers, and adhesives used in the manufacture of solid rocket FIGURE80.--Bond sensitivity to contamination. motors, will become severely limited in 1995. This will have a significant To assess the selected aqueous-based Although many factors will affect the impact unless suitable replacement cleaners, test panels coated with decision of a solvent-based cleaner materials are identified, character- hydrocarbon grease were spray- replacement, the Turco 3878 LFNC TM ized, and put into use in the near cleaned with Brulin 815 TM or Turco and Brulin 815 TM are both effective term. Part of the effort of the MSFC 3878 LFNC TM or were exposed to a on hydrocarbon grease. The new Solid Propulsion Integrity Program standard vapor degreaser with 1,1,1 aqueous-based primer/adhesive (SPIP) has been to identify, charac- trichloroethane. All panels received system recommended for bonding terize, and help implement replace- ment materials for the shuttle surface inspection and were then EPDM to steel performs as well as primed and adhesive-coated with the solvent-based system in produc- redesigned solid rocket motor case/ either the solvent-based system or ing a bond that is tolerant to grease insulation bondline, which utilizes a the aqueous-based system. Both the contamination levels up to 200 mg/ft 2. Kevlarr_-filled ethylene propylene diene monomer (EPDM) rubber surface analysis and the bond test bonded to steel. data show that the aqueous-based Sponsor: Solid Propulsion Integrity cleaners performed equally well in Program, Office of Space Systems removing hydrocarbon grease from Development Two candidate replacement cleaners, the steel surface. an aqueous-based primer and an Commercial Involvement: Science aqueous-based adhesive for Kevlar TM- The bond sensitivity to contamina- Applications International Corporation filled EPDM, were chosen for study. tion was assessed by recontamina- Peel and tensile button tests were ting clean panels with HD-2 grease, conducted to determine bond prop- a common hydrocarbon grease, to erties of a vulcanized EPDM/steel known levels. While the aqueous- bond utilizing these aqueous-based based primer/adhesive system is not materials and to assess the sensitivity as tolerant of hydrocarbon contami- of the bondline strength to hydrocar- nation as the solvent-based system, bon contamination relative to current it showed no bondline degradation solvent-based materials. below 200 mg/ft _ (fig. 80).

116 Technology Programs

Development of an 300 Advanced Solid Propellant Simulant • - - hevi0usInerth0pellanl| - - SPIPAdvancedLivePropellantInerlPropellantI| | M. Louise Semmel/EH33 205-544-3650 q'l 2O0 Typically, inert propellants have

been developed for very limited use o_ i J ° ° and are not representative of live L propellant overall. Because the solid ,je rocket motor (SRM) manufacturers ,I have the facilities to mix, cast, and test live solid propellants, there 100 seemed to be no real need to invest in the development of an inert pro- pellant that simulated live propellant for a variety, of purposes. However, / ...... ,. for the past few years, the SPIP has been working to improve the reli- ability of solid rocket motors through • I I I I - a series of efforts focusing on solid 10 20 30 4O motor design and fabrication. Some Strain Percentage members of the SPIP team do not Prapellon!MaterialResponse have the facilities to handle live Slressvs.StrainCurves propellants; also, development ef- Temperature= 75 °F,Cross-BeadSpeed= 2in/min forts are, by necessity, more limited and more costly with a live propel- FIGURE81 .--Live-inert propellant comparison. lant than with an inert material. For these reasons, the SPIP bondlines task team began development of an not been used in inert formulations modified to optimize the packing inert propellant that would satisfy because they do not react with fillers fraction and achieve acceptable the team's multiple requirements. (NaC1, sand, etc.). These bonding processing. The approach taken in the develop- agents greatly increase the propellant ment of the advanced inert propel- strength by bonding the AP and the With the process modifications, the lant was to substitute ammonium polymer matrix together and pre- advanced inert propellant processes sulfate (AS) for the oxidizer; all other venting early dewetting of the solid well and typically has an end-of-mix ingredients would remain the same particles. The resulting inert propel- viscosity of 5 kP. Joint Army, Navy, at typical concentrations. The AS lant produces the same type of bond NASA, and Air Force (jANNAF)- concentration in the advanced inert reinforcement and mechanical prop- type C dogbone samples were tested propellant is within 10 percent of the erties behavior as is seen in live over a temperature range from 0 to ammonium perchlorate (AP) concen- propellant. 120 °F and compared to the data tration typically used in hydroxy- collected for a previous inert and a terminated polybutadiene (HTPB) The high level of AS made initial live propellant being used in the propellants and provides a much mixes of the advanced inert propel- SPIP program. The 75 °F data are more realistic relationship between lant difficult to process. It was specu- shown in figure 81. the binder and filler. lated that the density change of the AS versus AP and the particle shape The modulus behavior and the coef- This approach also allowed the use significantly changed the packing ficient of thermal expansion indicate of bonding agents, such as HX-752 TM fraction of the solids. This required that the advanced inert propellant and Tepanol TM, which have typically that the coarse-to-fine AS ratio be simulates live propellant over a wide

117 Research and Technology 1993

temperature range. Based on these Carbon Phenolic these tag-end tests are one of the data, it was shown that the advanced Ablative Materials criteria governing whether each part inert propellant exhibited properties Test Methodology will be accepted or rejected for use similar to those of live propellant, in flight motors. and that the AS/HX-752 TM reaction produced solids bonding similar to Cindy G. Upton/EH34 The acceptance tests were initially that of AP/HX-752 TM. 205-544-5755 selected to discriminate between parts that had or had not received Evaluations of the insulation/liner/ To improve the reproducibility, inert propellant bondlines were per- adequate processing and to detect reliability, and uniformity of SRM deviations from the historical data formed using a conical bond-in- nozzles, a NASA-sponsored SPIP base that might indicate an out-of- tension (C-BIT) specimen. The has established an industry advisory results indicate that the bondlines experience performance of the part committee to improve test methodol- present in the samples cast with the during firing. These tests are: re- ogy for carbon phenolic materials, advanced inert propellant provided sidual volatiles, compressive strength, including constituents, prepreg, and bondlines with strength very similar resin content, and specific gravity. cured materials. The industry advi- to that of the live propellant. Failure All of these tests were initially se- sory committee is a voluntary group modes were 100-percent cohesive in lected over 10 yr ago. Since then, that is represented by domestic aero- propellant. much more has been learned about space material suppliers, fabricators, the behavior of carbon phenolic The data indicate that the advanced design organizations, and testing materials in their use environment. inert propellant can effectively repre- agencies. The committee has met sent live HTPB propellant with re- biannually since 1988 to improve Several types of anomalous behavior spect to mechanical, rheological, and the performance of American- have been observed both in flight bondline properties. This propellant manufactured SRM nozzles. and in static motor parts that had simulant is an ideal substitute for passed all acceptance criteria. Further- testing in laboratories that are not An example of one of the com- more, there has not been a trend in equipped to work with live propel- mittee's activities is the selection of acceptance test data that would sug- lants, while generating useful data gest that there was a difference be- directly applicable to current solid new and improved acceptance tests tween anomalous and nominal propellant programs. It also provides for cured phenolic materials. Ablative the solid propulsion community with components for the space shuttle performing parts. Figures 82 and 83 a safer, lower cost alternative to live SRM's are manufactured from tape- show the relationship between two propellant for shipping, training, and wrapped phenolic resin preim- acceptance tests presently employed technique development. pregnated carbonized rayon cloth for parts (cowl and outer boot ring, (prepreg). The parts are then cured respectively) that performed satisfac- Sponsor: Solid Propulsion Integrity at elevated temperature and pres- torily, and those that exhibited Program, Office of Space Systems sure. Tag ends of each ablative com- wedgeout--an anomalous and po- Development ponent of the nozzle and exit cone tentially dangerous behavior. Clearly, Commercial Involvement: Science of each solid rocket motor are re- there is no relationship between Applications International Corporation moved for testing. The results of the data and the performance.

118 Technology Programs

Torch-Produced Diamond 0 n Films 37 ODO nm o r-lA [] Floyd E. Roberts III/EH34 3,t oA • [] _ o Aoo 36 0 I-IDI_ o Nooo ° 205-544-1967 as[ oO • o o Continuous films of diamond offer a 121 number of outstanding material prop- O erties with practical application in "_ ° 0 o o [] 32 o aerospace systems. Diamond boasts Io W'_houtl_.lilidAnomalousEvenlsI 31 [] °°°° the highest hardness and the highest • IdenlifiedWedgeou!Evenf_ I i room-temperature thermal conductiv- 301 _ _ o j I I I I I ity of any known material. Diamond 0 lO 20 30 40 50 60 l0 80 90 also possesses a small coefficient of Material IdentificationNumber thermal expansion and a low coeffi- cient of friction. Diamond films have FIGURE82.--SRM/RSRM cowl resin content (mean values). applications in areas such as impact- resistant surfaces, turbine blade edge 42,000 coatings, cooling tube surface coat- ings, and combustion chamber n WithoutIdentifiedAnomalousEventsI o o linings. '_---_37,000 This year, MSFC has initiated an atomic force microscope (AFM) study ooooo of torch-produced diamond crystals. 32,000 The diamond films grown in the oi designed experiment are undergoing oooooo° oD DO0 n rl n surface structural analysis on the I 2z,000 [] AFM. This work is being done in 0 [] parallel with the chemical dynamics 0 0 simulation run on the two-dimen- 03 0 22,000 I I I I I I I l 1 I sional kinetics (TDK) program. This 10 20 30 40 50 60 70 BO 90 1O0 110 program is commonly used in the Material IdentificationNumber analysis of exhaust plume gas phase constituents for rocket nozzles. MSFC FIGURE83.--SRM/RSRM outer boot ring compressive strength (mean values). is using a simulation run of the pro- gram for gas phase analysis of the deposition structure. The surface This, along with similar observations cured carbon phenolic composites structures noted on the surface of made between acceptance test data are of limited value. This SPIP indus- samples will be compared with the from all 4 tests, and 5 of the 10 his- try advisory committee has initiated a preferred surface displayed by the possible constituents identified by the torically worst performing parts in process that will result in the recom- chemical kinetics program. Figure 84 the redesigned solid rocket motor mendation of additional and alterna- shows a 2- by 2-la sectkm at a Z mag- (RSRM), indicated that presently em- tive cured composite acceptance nification of 50 A of a diamond crys- ployed acceptance tests were not tests for SRM programs. tal surface from the AFM. MSFC is completely adequate for prediction working to extend this analysis to Sponsor: Office of Space Flight of performance. the bulk of samples. The program is adding an air table to the microscope At this time, there is general agree- ment in the rocket nozzle commu- nity that existing acceptance tests for

119 Research and Technology 1993

Development of Low Thermal Conductivity PAN-Based Fibers for SRM Nozzle Applications

Roymond G. Clinton/EH34 205-544-2682

In late 1989, the Materials and Processes Laboratory initiated a re- search program to develop and evaluate low thermal conductivity (LTC) polyacrylonitrile (PAN)-based carbon fibers as potential replace- ments for rayon-based carbon fibers traditionally used as reinforcement in carbon cloth phenolic ablative nozzle material applications.

FiGuRE84.--Atomic force microscope image oF A PAN fiber replacement offers sup- 100 diamond crystal 2; by 2-g at plier stability, multiple domestic Z magnification of 50 A. sources, and a greater resistance to the characteristic rayon-based carbon setup to achieve atomic level surface mode, or data may be collected on phenolic pore pressure-driven failure imaging. The ongoing work is fo- real-time stripcharts and stored in modes, based upon laboratory and cused on a series of designed experi- spreadsheet format for posttest subscale SRM test results to date. ments that will fine-tune some of the analysis. A shell is supplied to allow The disadvantages of PAN, including developments of the past year. The macros, which are test-specific, to high thermal conductivity, increased project work, done in conjunction be easily added to the system. weight, and lower resistance to de- with Rocketdyne, is continuing and (The program is available through lamination are being addressed in is structured around optimization of COSMIC®.) The space station group the subject program. related alternate processing avenues. is also using software developed in This work will comprise the bulk of the MSFC diamond lab to test com- Results from Phase I of the LTC PAN the final project phase. ponents of the CO 2environmental air fiber development effort have been recycling system test loop. The soft- reported elsewhere (Clinton et al. The technology developed in this ware has been transferred to this 1990). A second series of forty- program has already seen use in group and required only cosmetic pound charge (FPC) motor tests was other programs at MSFC. The Pyro- change before being used in the defined, based on the results of laser System Software developed to space station CO, recycling compo- Phase I tests of both the FPC sub- monitor the changing emissivity and nent test setup. scale SRM and the MSFC nozzle temperature of a growing diamond film, has been accepted into NASA's Sponsors: Office of Space Flight, insulation test motor (NITM-2) sub- Computer Software Management and and Marshall Space Flight Center scale SRM, plus industry input from Information Center (COSMIC ®) distri- Director's Discretionary Fund the SPIP PAN development work- shop in which a drop-in rayon re- bution program. The pyrolaser pack- Commercial Involvement: age is an operating system for the placement was voted as top priority. Rocketdyne, A Division of Rockwell pyrolaser pyrometer. Temperature The background, approach, and International and emissivity measurements may be materials descriptions for the Phase II either collected as if the pyrometer series are provided in Research and were being operated in the manual Technology 1992 (Clinton 1992).

120 Technology Programs

• 92.02cm _ I

f-" MX4926 _ / I I 7 / ,-.. MX4996B /,_ I I _/-_ _ FM5939LOC

/ FM5055B IJ _ FM5950 _-" FMSO55B | FM5952 FM5950 / FM5952 12.669cm

FIGURE85.--Cross-sectional view of SPIP-3 MNASA nozzle.

The prima W objective was to gener- Rationale for downselection of mate- Based upon these factors and crite- ate char- and erosion-performance rials to be tested in the SPIP-3 ria, the SPIP team selected the data on candidate PAN-based abla- MNASA motor fell into two catego- Hercules LFP-2 and Amoco 25 fibers, tive materials in an SRM environment ries: performance factors and pro- with B.P. Chemicals/Ironsides 91LI) TM for evaluation and downselection of grammatic issues. Using the thermal phenolic resin to be tested in botil rayon replacement materials for performance data from FPC tests, standard and low-density formula- scale-up to modified-NASA (MNASA) erosion rate and total heat affected tions. Product codes for these mat- subscale SRM tests and subsequent depth were component-specific erials are the following: FM5950 process optimization. These perfor- weighted for performance evalua- (LFP-2/91LI)); FM5952 (Amoco 2W mance results from the Phase II test tion. The PAN thermal performance 91LD); FM5951LI)C (LFP-2/91LI)); series are provided in table 5. Sec- was compared hy component with FM59S3LI)C (Amoco 25/91LD). ondary objectives relating to this an expected range for rayon-based project included the evaluation of ablatives established with FMS055B Placement of these materials within fiber/fabric heat treatment effects, a as baseline. Post-fire conditions, the SPlP-3 MNASA nozzle, which performance comparison of spun- which were cause for rejection, were utilized a replacement MNASA versus continuous-fiber reinforce- excessive cross-ply expansion and nozzle design, is shown in figure 85. ments, evaluation of resin system wedge-out. Post-fire conditions that The approach was to enable both effects, and evaluation of tow size/ served as tie-breakers were pocket- standard density LTC PAN candidates weave effects. A complete discussion ing in the 90-degree section and to be compared to each other and to of the analysis of the results in the plylift. Programmatic criteria were a "control" or baseline rayon-based above categories is beyond the cost, product availability, process- ablative material (FMS055B was se- scope of this summary, but has been ability of prepreg, and PAN precur- lected), in the same environment. reported by Emery and Hill (1992). sor source (foreign or domestic), This was accomplished by bonding

121 Research and Technology 1993

TABLE5.--Erosion rate and heat affected depth results from Phase II FPC motor tests

MX4933 76 4.8 161 0.82 119 85 127 144

MX4934 87 5.5 153 0.78 113 120 127 140

T300/91LD 89 5.6 129 0.66 113 129

MX4904 5.7 143 0.73 111 117 122 132

VCX14/P39 5.8 137 0.10 llS 119 128

Amoco23/P39 5.8 135 0.69 114 118 126

MX4963 137 0.70 112 116 120 129

AvcarbB2/91LD 0.52

FM5796 122 0.62 111 113 118

FMSOSSB 0.51

MX4952 6.7 149 0.16 123 128 132 140

LFP-2/91LO 6.8 114 038 III 112 113

MX4926 6.8 116 0.59 III 112 113 114

Amoco2.$/91LD 0.55

113 0.46 Ill

LFP-2/P39 114 7.2 118 0.60 116 I 116 114 116 J 117 AS4/P39 117 7.4 O.$2 111 116

BASF-2/SCI008 119 7.5 137 0.70 126 128 121 130 133

kmoco23/91LI) 121 7.6 118 0.60 120 120 121 119 119

MX4972 122 7.7 131 0.67 126 127 123 127 129

LFP-2/SCIO08 124 7.8 0.55 118 116 122 114 121

FMSO14 125 7.9 112 0.57 120 119 124 117 115

AvmrbB2/SCIOO8 125 7.9 116 0.59 121 119 124 120 118

Amoco23/SC1008 129 8.1 0.56 121 120 127 118 I14

BASF-1/SCIOO8 130 8.2 122 0.62 127 126 129 125 124

LFP-I/SCIO08 137 8.6 112 037 127 125 135 122 117

AvcorbB25/91LD 137 8.6 114 0.$8 128 126 135 123 118

AvcarbGS/91LO 152 9,6 0.51 131 126 147 121

AvcarbG/SC1008 154 9.7 0.55 136 131 149 126 117

AvcarbG/91LD 156 9.8 0.54 136 131 126 116

IRatin_basedon FM5055coetro100%= FMSO55Bl_irfo_monce,_Iodcboxesindkale±10_ tolerancebandoboutFMSO55Bperfm'mance.

122 I Technology Programs

equal sections of the three materials Enhanced Aerospace 1970's, scientists began to believe to form a single ring for the forward Insulation Systems that CFC's had a detrimental effect inlet, throat, and forward exit cone. on the Earth's stratospheric ozone As it was impractical to reconstruct layer. Subsequently, an international Edwin A. Weaver/EH35 an aft exit cone by bonding full- agreement--the Montreal Protocol-- 205-544-3466 length axial sections, low-density was ratified to phase out the use of materials were incorporated in the CFC's. The phaseout of CFC's in the Historically, the external tank program form of circumferentially continuous ET program is scheduled for comple- has relied on the commercial ure- sections (fig. 85). The FM5939LDC tion in 1996. Hydrofluorocarbon thane market for its foam insulation material is the rayon-based material (HCFC) 141b with greatly reduced systems. However, with more than selected h)r use in a replacement ozone depletion potential (ODP) 99 percent of the urethane market nozzle and will serve as the low- will be implemented as the blowing dedicated to less demanding applica- density baseline for comparison in as agent for TPS materials, but this tions (construction, furniture, etc.), much as this can be accomplished second generation blowing agent commercial systems suppliers are considering the variation in environ- will also be regulated and eventually Wpically not motivated to develop ment within the aft exit cone. banned, currently scheduled for the materials to specifically meet strin- year 2002. The SPIP-3 MNASA motor was tested gent ET design requirements. This-- at MSFC in September 1993. PerK)f- along with the fact that foam system The ff)cus of the MSFC TPS Materials inance results from this test will be suppliers tend to change their raw Research Laboratory is to evaluate provided in the 1994 annual report. materials or processing methods to address the needs of their bulk mar- and develop a data base for third Clinton, R.G., Jr.; Pinoli, P.C.; and generation blowing agents with no ket to match competitors and/or Canfield, A.R. October 1990. Devel- ODP. In the evaluations, the compat- comply with changing Environmen- opment of Low Thermal Conductiv- ibility and solubility of potential ity PAN-Based Fibers for Solid tal Protection Agency (EPA) and blowing agents with isocyanate and Rocket Nozzle Application. JANNAF Occupational Safe W and Health Act Rocket Nozzle Subcommittee Meet- (OSHA) regulations--results in un- polyol foam components is tested, ing, Pasadena, CA. certain continued availabili W of ET the effect of the foaming reaction is thermal protection system (TPS) quantified, and, if necessary, com- Clinton, R.G., Jr. 1992. Development of pensated for by change in blowing Low Thernla/Conductivity PAN- materials. Over the life of the ET pro- agent and/or catalyst levels; in the Based Fibers for SRM Nozzle Appli- gram, this uncertainty has been dem- cations. Research and Technology, onstrated by over 10 uncontrollable final stages of the evaluation the mechanical and physical properties 1992: Annual Report (f the Marshall changes to TPS materials, resulting of foams produced with the third Space b:light Center, NASA TM- in costly requalification programs 103559. generation blowing agents are tested. and potential loss of sole-source To date, several materials have been Emery, E.A., and Hill, K.tl. December suppliers. 1992. PAN Material Performance investigated as third generation blow- ing agents. These include fluorinated Evaluation. JANNAF Rocket Nozzle To address this lack of visibility and Subcommittee Meeting, Lockheed control of ET TPS materials, NASA ethers, fluorinated hydrocarbons, per- Missiles and Space Company, decided, in 1987, to establish a labo- fluorinated pentane, gaseous hydro- Sunnyvale, CA. CPIA Publication flourocarbons, and water that reacts ratory capable of formulating TPS 592. materials specific to ET requirements. with the isocyanate component to produce carbon dioxide gas that acts Sponsor: Office of Space Systems This laboratory is now operational, as a foaming agent. Development and the primary focus is the devel- opment of TPS systems that are foamed with "environmentally Sponsor: Office of Space Flight friendly" blowing agents. All cur- Commercial Involvement: Martin rently used ET foam insulations are foamed or "blown," with chlorofluo- Marietta Corporation rocarbon (CFC) 11. With the advance of the Rowland-Molina theory in the

123 Research and Technology 1993

Fiber Placement: New A project in the Center Director's Environmentally Friendly Technology for Discretionary Fund program is the Sprayable Ablator for the use of fiber placement capabilities to Automated Composite Solid Rocket Booster investigate a fully automated com- Manufacturing posite processing method for fabrica- tion of an optimally designed optical Carl N. Lester/EH35 205 -544-4804 John H. Vickers/EH35 bench. The primary justification for 205-544-3581 selection of these materials is the ability to maintain precise focal Progress has been made in the continuing effort to develop and Automated fiber placement is a length without thermal control or qualify an environmentally friendly manufacturing process used for pro- active focusing systems; coefficients replacement for the ablator currently ducing complex composite structures. of thermal expansion of zero can be obtained. While structures are suc- used for the space shuttle SRB's--- It represents a significant advance- Marshall sprayable ablator-2(MSA-2). ment in the state of the art for auto- cessfully fabricated for this applica- tion, they are manufactured as one- The MSA-2 ablator performs well, mated composite manufacturing. of-a-kind and primarily by hand. The but will be phased out because of Fiber placement capability was es- fiber placement process will supplant impending environmental regulations tablished at the MSFC Productivity the considerable manual element of due to its chlorinated hydrocarbon Enhancement Complex in 1992, in this fabrication process, thereby in- solvent system. Two environmentally collaboration with the Thiokol creasing repeatability and improving friendly candidate systems to replace Corporation. analysis and correlation of resultant MSA-2 include MSA-3--a third-gen- data. eration, water-based ablator--and Fiber placement was developed as a United Space Boosters, Inc. (USBI) Spot.ors: distinct solution to problems inherent Marshall Space Flight Sprayable Insulator (USI), which has Center Director's Discretionary Fund, in other automated composite manu- recently gained prominence after Payload Projects Office, Space facturing systems. This equipment emerging from a USBI independent Shuttle Projects Office, and Office of provides unique capabilities to build research and development (IR&D) Advanced Concepts and Technology, composite parts in complex 3--D project as a viable replacement can- Technology Utilization Office shapes with concave and other didate. The goal is to have a quali- asymmetrical configurations. Commercial Involvement: Thiokol fied replacement for MSA-2 in Corporation production by 1996.

MSA-3 predecessors--MSA-1 and MSA-2--were first flown on the SRB's in November 1981 and March 1989, respectively. MSA-2 provided a more flexible resin system that im- proved flight performance and could be sprayed more thickly without cracking, which expanded the appli- cation of the ablator to new areas of the SRB.

124 Technology Programs

MSA-3 consists of water-dispersible Resin/Catalyst60.0% resin, surfactant, defoamer, thixotro- pic agent (Bentonite), and fillers such as ground cork, glass fibers, and glass spheres (fig. 86). It is robotically sprayed on a painted aluminum target located on a rotat- ing turntable. After curing, the ablator is top-coated with a moisture- resistant paint to help maintain its Defoomer0.6% strength and integrity. A high-tem- perature cure provides the quickest processing timeline, although an Chopped6.35mm ambient cure is being investigated. Fiberglass3.0%

Bentonite3.2% Preliminary thermal characterization Surfactant1.0% has been accomplished, as has sensi- tivity testing to study the production tolerances for mixing, applying, curing, and repairing the material on an actual flight structure. After GlassEccaspheres26.2% completion of the development phase, the material will be ready for FIGURE86.--Typical composition of cured MSA-3 in weight percentage. qualification and transition into the production spray ceils, where final (MSA-3 or USI) is transitioned to one of the nation's preeminent validation will occur, production, based on such factors as research centers. Considering the cost-effectiveness and robustness of impending environmental regula- USI is another innovative ablative process. tions, the implementation of a com- concept that employs an epoxy resin pliant replacement for MSA-2 is with ground cork and glass fillers in The Air Force was sufficiently of critical importance to the space a solventless, convergent spray pro- impressed with these materials to shuttle program. These environmen- tess. Features of this process include participate in a joint effort to qualify tally friendly materials will be avail- on-demand availability and ambient- an MSA-2 replacement material for able for other launch programs as cure capability. This technology the Titan IV rocket payload fairings. well, as evidenced by the Air Force has been transferred to the MSFC Currently under way, this effort will Titan IV application, and will reaf- Productivity Enhancement Com- attempt to utilize as much of the SRB firm NASA's commitment to the plex Sprayable Ablator Research development and qualification work ecology of our planet. Cell, where it is being developed as possible. along with MSA-3 as a candidate Sponsors: Solid Rocket Booster replacement for MSA-2. Prior to In developing MSA-3 and USI, the Project Office, and Office of Space implementation, a decision will be Productivity Enhancement Complex Flight made as to which of the materials at MSFC is fulfilling its mission as

125 Research and Technology 1993

II I I II Mission Operations

Virtual Reality simulations will be validated, where the Eyephone LX (stereo views) with Applications Program possible, through empirical compari- one or two DataGloves TM (i.e., both sons with existing, accepted toolsL right and left hands, simultaneously). and methodologies. These validated A two-person configuration is pos- Joseph P. Hale II/E023 VR analytical tools will then be avail- sible and consists of both Eyephones 205-544-2193 able for use in the design and devel- (monocular views) with one Data-

opment of space systems and oper- Glove TM associated with the Eye- The objectives of MSFC's Virtual ations, and in training and missions phone Model 1, and up to two Reality (VR) Applications Program support systems. DataGloves TM associated with the are to develop, validate, and utilize Eyephone LX. In the two-person VR as a human factors design and The MSFC VR systems reside in the configuration, both participants are operations analysis tool, and to as- Computer Applications and Virtual in the same Virtual World (VW) sess and evaluate VR as a tool in Environments (CAVE) Laboratory in simultaneously and each is able to other applications (e.g., training, building 4610. System components see and interact with the computer- operations development, mission consist of VPL Research, Inc., Eye- generated image of the other. support, teleoperations planning, phones (Model 1 and LX), Data- etc.). The long-term goals of this Gloves TM, and software (Swivel 3-D, technology program are to enable Several VR development activities Body Electric, and ISAAC); Polhemus specialized human factors analyses are under way at MSFC and with JSC. IsoWak and Fastrak spatial tracking earlier in the hardware and opera- EXOS, Inc., is under a Phase II SBIR systems; two Macintosh llfx comput- tions development process, and to contract to develop a Sensing and ers; and two Silicon Graphics, Inc., develop more effective training and Force-Reflecting Exoskeleton graphics computers (4-D/310VGX mission support systems. (SAFiRE) for the hand. This device and 4-D/320VGXB). Figure 87 shows will provide force-reflecting feedback a user donning the specialized VR The capability to perform specialized to the fingers and hand as the user gear. Figure 88 shows a fully outfit- human factors analyses earlier in the touches and grasps virtual objects. ted VR user. Two single-person con- hardware and operations develop- Tomorrowtools, under a Phase I figurations are possible. These ment process is required to better SBIR contract, is developing a 30- are the Eyephone Model 1 (stereo refine and validate requirements sensor spatial tracking system. Using views) with one DataGlove TM and during the requirements definition ultrasonics to determine the location phase. This leads to a more efficient of each of the sensors and infrared design process where perturbations to transmit data to the base units, caused by late-occurring require- this system will provide an unteth- ments changes are minimized. A ered method to track up to 30 body validated set of VR analytical tools points and other objects simulta- must be developed to enable a more neously. This will be particularly efficient process for the design and useful in dynamic work envelope development of space systems and analyses. In-house work is under operations. Similarly, training and way to broadcast the video signals to mission support systems must exploit the Eyephones, removing the video cable to the user that is now re- state-of-the-art computer-based tech- nologies to maximize training effec- quired. Integration of the two latter tiveness and enhance mission activities' products will free the user support. from existing input/output (I/O) cables. The approach of the VR Applications Program is to develop and validate MSFC is cooperating with JSC in their appropriate virtual environments and efforts to develop a long distance associated object kinematic and be- two-person capability using their in- havioral attributes for specific classes house-developed VR system. Long of applications. These application- F_GURE87.--User donning the distance capability would allow two specific environments and associated specialized VR gear. people to simultaneously see and

126 Technology Programs

are candidates for VR. It is not that VR would completely replace these other technologies and techniques, but rather will add another tool to the analytical tool kit.

In some instances, VR might be considered for use in an analysis that would have otherwise not been un- dertaken. Resources (time, people, materials, etc.) required for a "stan- dard" simulation or mockup analysis may be greater than the expected return. In this case, VR, due to its relatively low utilization costs, would surpass the cost/benefit ratio thresh- old and enable an analysis that would have otherwise been fore- gone. Similarly, VR can enhance and enable more effective utilization of standard simulation and mockup analyses. By preceding these analy- ses with preliminary VR analyses, both the hardware and operations Ftou_E 88.--Fully outfitted VR user. can be refined so that the return from the standard analyses is in- interact with the computer-generated what one is able to see from a variety creased. This is accomplished by image of the other in the same V'W, of eye reference points. These analy- either reducing the magnitude or with one person at JSC and the other ses can also include operationally number of standard analyses and at MSFC. Basic capabilities have driven components such as transla- improving the fidelity of those analy- already been demonstrated. As VR tion paths among the various ses with a more mature design. Be- technology evolves, this virtual link worksites. Combined with scaleable cause the VW's are nothing more between, and eventually among, the user anthropometry attributes, than computer files, design changes NASA centers may provide both microergonomics analyses for the can be done more quickly and, sub- major foreseeable and unanticipated spatial layout of workstations can sequently, more candidate configura- benefits. consider what one is able to see tions can be analyzed than are from a variety of eye reference currently possible with existing standard human factor tools points and what one is able to touch Human factors issues and consider- from a variety of shoulder and seat (e.g., Fomecor TM mockups). ations in hardware and operations reference points and/or foot restraint development present a large class Several VR applications validation locations, using a range of virtual of potential VR applications. VR studies are under way at MSFC. The anthropometric sizes. technologies and techniques cur- selected applications are those that rently provide some limited macro- can utilize existing VR technology ergonomic and microergonomic Many analyses that use Fomecor TM and capabilities. Before VR can be analytical tools for consideration of mockups (full-scale "cardboard" used with confidence in a particular operational, viewing, and reach en- mockups), the KC-135 (plane that application, it must be validated for velope requirements, in both one- provides approximately 30 s of that class of application. For that gravity (Earth) and microgravity weightlessness during each cycle of reason, a specific validation study (space) environments. Macroergo- parabolic flight), or the Neutral has been proposed for classes of ap- nomics analyses for the topological Buoyancy Simulator (underwater plications. The validation approach is design of work areas can consider facility for simulating weightlessness), to compare the results from the VR

127 ResearchandTechnology1993

analyses or applications with a spe- (Good/Poor), with Gender as a In a second activity, support was cific past or present analysis, design, blocking variable. "Nested" within provided to the 30-percent design and/or actual flight experience. the Design variable, the subjects will review of the space station Payload either estimate the range to items Control Area (PCA). The PCA will be Early applications utilizing the VR (Range Estimation) or choose the payload operations control room, system currently in place at MSFC fall (forced) which of a pair of objects is analogous to the Spacelab POCC. primarily into viewing analyses (in- closer (Relative Range). The Range Several configurations of the console cluding visualization of spatial lay- Estimation IV's are item (Object/ floor plan layout, large video outs) and reach-envelope analyses. A Surface) and the item's range from screens, and public viewing area VR validation study is under way to the observer (Near/Far). The Relative were modeled in Swivel 3-D. De- develop, assess, and validate VR as a Range IV's are Field of View (FOV) signers, management, and the Public macroergonomics analysis tool for (Same/Different; i.e., whether or not Affairs Office (PAO) utilized the the topological design of work areas. the subject can see both objects system to immersively visualize the Two existing control rooms and their simultaneously in the same FOV), options. PAO evaluated the view corresponding virtual counterparts and the objects' range from the ob- from the public viewing area at vari- will be used to collect subjects' server (Close/Away). Adjective-pair ous raised floor heights and per- qualitative and quantitative judg- Likert scales, range estimation, rela- formed a preliminary camera viewing ments on a variety of measures. The tive range forced choice, and elapsed analysis, "flying" to various possible MSFC Spacelab Payload Operations time to answer range questions will camera locations to inspect the com- Control Center (POCC) and the Data be collected as dependent variables position of the possible camera Control Room (DCR) have been (DV's). FOV's. The ability to pan and tilt and selected, based on their apparent change "lenses" (i.e., narrow to separation on a variety of continua The MSFC VR capability has already wide-angle FOV's) in real time was (e.g., large/small, spacious/cramped, been utilized in a couple of activities. especially useful. aesthetically well/poorly designed, Both primarily involved immersive etc.). A corresponding Virtual POCC visualization of architectural spaces. Sponsors: Space Station Projects (VPOCC) and Virtual DCR (VDCR) One supported the recent move of Office; Marshall Space Flight Center have been developed that contain the CAVE Laboratory into its new Director's Discretionary Fund; Office the basic elements (e.g., tables, quarters. Two different laboratory of Advanced Concepts and Technol- monitors, printers, communication layouts were developed and mod- ogy, Small Business Innovation Re- panels, etc.) and spatial layout of eled in Swivel 3-D. Several of the search Program; Summer Faculty their real-world counterparts. lab staff then "entered" the virtual Fellowship Program; Historically laboratories and evaluated the con- Black Colleges and Universities; Forty-eight subjects (24 males and figurations as both users and visitors. Engineering Technology Base 24 females) will participate in a Layouts were modified near real time (Institutional) within-subjects design study. Over'all and reevaluated. Based upon these independent variables (IV's) include evaluations, one modified layout was ¢on_,r_ercial Involvement: EXOS, World (Real/Virtual) and Design chosen and implemented. Inc., and TomorrowtooLs

128 Technology Programs

A Dynamic Human- Horowitz 1991) and enables interac- Computer Interface tive usabi]ity studies and acceptance testing. The goal of prototyping, Prototyping Environment usability studies, acceptance testing, With Embedded and so forth, is to force as much of Evaluation Capability the evolutionary development as possible into the preimplementation Joseph P. Hale II/EO23 phase, when modificati(}ns are rela- 205-544-2193 tively easy and inexpensive (Schneiderman 1992).

Many of the activities and functions The objectives of this project are to at MSFC and, for that matter, develop and assess a dynamic ttCI throughout the agency, take place FIGURF89.roUser of a workstation prototyping environment with em- with an HCI. via a computer interface. Commer- bedded evaluation capabilitT. There cially available applications (e.g., are four key tools or capabilities word processors and spreadsheets) necessary for the dynamic proto- come with their own human-com- "look-and-feel" of the HCI. Thus, the typing process. First, a tool is re- process to develop the HCI require- puter interfaces (HCI's). However, quired to build and spatially arrange since much of the work at MSFC is ments and specifications has gained the various buttons, widgets, icons, increased importance. Ideally, this done with specialized and prototype menus, etc., that populate a com- process should employ an iterative systems and processes, unique HCI's puter display. A second tool is re- "test-and-revise" methodology where must be developed and tailored to quired to develop a simulation of the the design requirements are devel- specific applications or environ- target system (}r process. Although ments. Figure 89 shows a user at a oped and extensively refined beg}re the resultant simulation does not workstation with an HCI. In many design implementation, minimizing require the fidelity of a training simu- cases, the HCI's must be developed costly (e.g., money and time) rework lat{}r, it must simulate enough of the of requirements or design that can either prior to the completion of a relevant functi{}nal attributes of the fully functioning target system or occur during later phases. Software target system or process t(} enable process, or isolated from the existing development problems usually occur usability studies and acceptance test- system/process. In both instances, during requirements specification, ing. Third is the capability to provide the HCI requirements must be devel- and it is here that elaborate feedback a dynamic, interactive interface be- loops are needed, though seldom oped without the benefit of interact- tween the prototype HCI, deve]oped provided (Budde et al. 1991). ing with the target system or process. with the first tool, and the simulati<}n At MSFC, these include the HCI's at of the target system or process, de- the test stands and laboratories, on Prototyping is a methodology based veloped with the second tool. Fi- the various Huntsville Operations on an evolutionary perspective of nally, a capability to evaluate the Support Center (HOSC) and POCC HCI development, producing early prototype HCI is required. This in- consoles, on the Spacelab Payload operative versions (prototypes) of cludes not only verifying compliance and General Support Computer the HCI's for subsequent evaluation to applicable styles, guidelines, and (PGSC), and, soon, on the space and revision (Budde et al. 1991). standards, but also measuring the station Payload Operations Integra- There are two basic approaches t() adequacy of the HCI t{} enable the tion Center (POIC) consoles and prototyping: static and dynamic user t(} control and maintain situ- onboard payload workstations. (Harken 1991). Static prototyl_ing ational awareness of the target sys- provides HCI's that can be demon- tem or process. Adequacy measures With the advent of today's advanced strated, but not used directly. This would consider such performance graphical user interfaces (e.g., icons, approach does not include the func- attributes as the type and frequency pop-up menus, virtual c(mtrol and tionality of the target process or sys- of errors, time and context (}f calls t{} display panels, etc.), the user's ability tem. Dynamic prototyping results in "Help," subtask completion times, to monitor and control systems and a testable simulation that provides a response times, and s¢) f¢}rth. Figure processes can be greatly enhanced fully functional HCI that can be "test 90 shows two users of the dynamic through proper attention to the flown" by the end user (Rouff and HCI prototyping system.

129 Research and Technology 1993

This project employs a graphical modeling approach to rapidly con- struct accurate models of complex systems and processes. It also in- cludes an embedded evaluation capability. This will facilitate the data collection, reduction, and analyses during usability testing and guide the HCI modifications for the next cycle. The development of an integrated dynamic prototyping environment with embedded evaluation capability will be a significant advance in the field of HC[ prototyping. By the end of this project, a capable prototype integrated system is anticipated. Further development and refinement will continue as the system is tested and applied.

Budde, R.; Kautz, K.; Kuhlenkamp, K.; and Z/Jllinghoven, H. 1991. Prototyping: An Approach to Evolu- tionary System Development. New York: Springer-Verlag. FICURE90.--Two users of the dynamic HCI prototyping system. Harken, S. 1991. Requirements Specifica- If done correctly, the evaluation will help reduce training costs and tion and the Role of Prototyping in would not only determine that an improve productivity in the opera- Current Practice. J. Karat (ed.). HCI is deficient, but point to specific tional environment (e.g., minimize Taking Software Design Seriously.. aspects or attributes of the HCf that errors, increase situational aware- Practical Techniques for Human- need improvement. A basic set of ness, enhance science return, etc.). Computer Interaction Design. evaluation metrics will be developed This project will develop and assess Pp. 339--54. Boston: Academic Press. and embedded in the integrated pro- an integrated dynamic prototyping Rouff, C., and Horowitz, E. 1991. A totyping environment. Thus, rele- environment. The currently existing System for Specifying and Rapidly vant evaluation data, based on the capability that comes closest to this user's interaction with the simulator Prototyping User Interfaces. J. Karat is the interactive link between the (ed.). Taking Software Design Seri- through the HCI, will be automati- CAVE Laboratory and the Payload ously: Practical Techniques for Hu- cally collected and logged during Crew Training Complex (PCTC), man-Computer Interaction Design. the evaluation session. The system where prototype displays can be Pp. 257-71. Boston: Academic Press. will then produce evaluation reports developed and linked to existing following the session. This task is Schneiderman, B. 1992. Designing the Spacelab training simulators. The probably the most theoretically chal- Userlnterface. Reading, MA: lenging aspect of this project. utility of employing this capability as Addison-Wesley. a dynamic prototyping environment is diminished because the training Sponsors: Marshall Space Flight The capability to efficiently engage simulators are delivered too late to Center Director's Discretionary Fund, in systematic dynamic prototyping be effectively used in prototyping Summer Faculty Fellowship Program, will significantly enhance the quality the displays. Further, the develop- and Engineering Technology Base and functionality of the resultant ment of the simulators requires the (Institutional) HCI's, while minimizing develop- knowledge and skills of a computer ment costs. The improved HCI's programmer.

130 Technology Programs

Alternative Illumination The sources currently being investi- building the device. The remote Technologies for the gated include subminiature fluores- system, which accesses sunlight via Human Habitation of cent tubes (7-ram diameter), twin- fiber optics or another "piping" sys- tube fluorescents, T-8 fluorescent tem, will be accomplished much the Space tubes, and light-emitting diodes same way. (LED's). Evaluation methodology Benita C. Hayes/E023 includes performance assessment Sunlight delivery systems will be 205-544-9276 via computer modeling, procuring pursued since this source has an samples, photometrically testing and "infinite" performance life, wide- Phase I of this SBIR reviewed new comparing the samples with com- spread availability, and excellent light source and control technologies puter models, and sending source color characteristics. These systems for applicability to interior spacecraft samples to subcontractors for build- will consider sunlight only, as well illumination. It investigated the inno- ing luminaire prototypes. as in combination with electric light- vative use of these sources which ing, to produce integrated electric/ have not previously been used in The second task--prototype sunlight delivery systems suitable for task and ambient illumination sys- luminaire development--will pro- use in areas of intermittent sunlight tems in spacecraft occupied by availability. humans. duce prototype indirect and direct/ indirect ambient luminaires, using one or more sources identified In Phase II, various sources and This Phase II SBIR has far-reaching above. These luminaires will be controls were evaluated and tested, commercial applications. It has been and recommendations made. The high fidelity. Additionally, task lumi- estimated that approximately one- naires will be manufactured using importance of this Phase II SBIR is third of the energy consumed in the the 7-mm or twin-tube fluorescent that it addresses methods of mini- U.S. is used in building operations, subcompacts. A medium-fidelity- In most commercial buildings, this mizing lighting power consumption, prototype task luminaire will be use profile is dominated by the inte- mass, and volume, while being atten- constructed using the LED source. tive to human factors requirements rior electric lighting system. The Evaluation methodology includes necessary to accomplish a range of American Consulting Engineering computer modeling of luminaires, visual tasks. As NASA plans kruger Council estimates that a typical manufacture of the prototypes, and duration missions and approaches a American now spends more than photometric measurements. The permanent human presence in space, 90 percent of their total life in an results of this will help identify po- spacecraft lighting systems will play artificial environment, yet most ef- tential uses in various enclosures and forts to reduce energy costs of elec- a significant role in determining the implications on a crew. habitability of human-occupied struc- tric lighting systems have sacrificed tures. Phase II is directed toward human-factor criteria for cost savings. Development and utilization of new three main tasks, including prototype The third task is the development of source development, prototype lumi- a sunlight delivery system. Currently, energy-efficient light sources that also satisfy human-factor require- naire development, and sunlight two options are being pursued to ments, such as color rendition and delivery system development. include a proximate system and a remote system. The proximate sys- glare control, have the potential to The first of these tasks--prototype tem, which is directly accessible to alter current design and construction source development--will identify sunlight via windows or skylights, approaches to building illumination on Earth. and develop new light sources for will be accomplished by selecting a use in spacecraft and habitats, or site in the solar system, generating a direct the use of existing sources computer model---considering ther- Sponsor: Office of Advanced Con- to space applications not yet tried, mal, construction, deployment, cepts and Technology, Small Busi- and will be sensitive to size, weight, and human-factor implications-- ness Innovation Research Program power, performance, and so forth. modifying for electric lights, and

131 Research and Technology 1993

III | II Propulsion and Fluid Management

Advanced Main Combustion Chamber Development

Henry J. Dennis/EP33 205-544-4670

Kathy S. Tygielski/EP33 205-544-4055

The Advanced Main Combustion Chamber (AMCC) Program was initi- ated to enhance the state of the art in design and fabrication of hydro- gen-cooled combustion chambers for large liquid rocket engines. Using the current SSME combustion chamber as a baseline, the AMCC design goals I I are to increase hardware reliability, reduce critical failure modes, and FiGuRE91.--Main combustion chamber fabricated by bonding formed platelet reduce fabrication time, at a cost less liner in cast structural jacket. than the current SSME combustion chamber. The AMCC incorporates a coolant manifolds, actuator lugs, An aggressive schedule is in progress to demonstrate the lower fabrication formed platelet coolant liner and a instrumentation bosses, and the con- single-piece cast structural jacket, troller mounting bracket. It is made time and costs by building the first both assemblies greatly reducing the of a hydrogen-environment-resistant, AMCC prototype for full-scale testing number of fabrication processes and nickel-based superalloy. Casting the in 1994. part variation (fig. 91). structure as a single piece eliminates most of the welds normally required Sponsors: Office of Advanced Con- The formed platelet liner technology for this WPe of component. cepts and Technology, Earth-to-Orbit is being developed with Aerojet of Propulsion; Space Transportation Sacramento, CA. This forming pro- These newer methods of fabrication Main Engine Project Office; and cess allows the liner to be made with have an added benefit of being able Space Shuttle Main Engine Project complex internal flow passages that to produce a combustion chamber in Office incorporate enhanced cooling fea- 12 too, compared to 40 to 60 mo tures to increase the life and durabil- for the conventional SSME combus- Commercial Involvement: Aerojet, ity of the part. The investment cast tion chamber. The cost for a produc- and Precision Castparts Corporation structure is being developed with tion AMCC is projected to be less Precision Castparts Corporation of than $1 million, compared to over Portland, OR. The cast structure is a $3 million for the conventional SSME single-piece part incorporating both combustion chamber.

132 Technology Programs

Formed Platelet Liquid Rocket Injector Combustor Liner Characterization Construction Feasibility JohnJ. Hu./EP13 Fred W. Braam/EP11 205-544-7125 205-544-7055 CharlesF. Scha_r/EP13 205-544-1642 Rocket engine combustion chambers must be cooled to withstand the A program for studying the atomiza- severe high-temperature environ- FJOURE92.--Comparison of subscale tion and mixing characteristics of ment that they contain. The construc- platelets to large-scale liquid propellant injector elements in tion of the cooling liners for the platelets. cold flow has been established at combustors is a time-consuming, MSFC. The program consists of ex- intricate, and costly operation. Cur- periments in three test facilities. The rent practice employs the use of first facility is designed to flow water, copper alloy liners with hundreds of air, or a combination of both through axial grooves machined in the outer a single injector element. The flow surface. These slots are closed out by exits the element to ()pen air and is an electroforming process, usually referred to as the Ambient Back using nickel, to form the cooling Pressure (ABP) Facility. The second passages. Machining tolerance capa- facility consists of a windowed high- bility currently limits the minimum pressure chamber designed to flow hot gas wall thickness to approxi- water and/or air through a single mately 0.635 mm, where wall tem- injector element at elevated back peratures are in the 732 °C range. pressure and is referred to as the High Back Pressure (HBP) Facility. FIGURE93.--Large-scale platelet An alternate cooling liner fabrication The third facility is based on acwlic cooling panels. approach is being investigated that models of liquid swirl injector ele- has the potential for reducing liner ments that allow visualization of the fabrication time by an initial estimate hot tested to chamber pressures of internal flow field, and is referred to of 50 percent and of improving the 17.6 MPa (2,550 lb/in 2 absolute) to as the Acrylic Model (AM) Facility. liner's cooling capability by lowering verify the design and fabrication wall temperatures to 177 °C. This approach. The platelet panels have The ABP facility is currently opera- alternate approach is based on the tional and can be used for the fol- use of diffusion-bonded stacks of been successfully scaled up to SSME size (figs. 92 and 93). These are lowing applications: copper alloy material sheets, called being prepared for installation into platelets, which are 0.20-ram thick or an investment cast structure for greater, and have been photoetched To characterize liquid/liquid assembly of a test article to demon- to form cooling passages. The plate- injector elements strate design integrity and manufac- let stacks are formed into contoured turing cost reductions of 80 percent To measure discharge coefficients sections by a stamping process and over the current design. and flow uniformity for gas/liquid are joined to form the desired com- bustion chamber liner. injector elements $lmnSots: Office of Advanced Con- cepts and Technololgy, and Space To develop diagnostic tools to be A nozzle assembly containing a used in the HBP facility zirconium copper-formed platelet Shuttle Main Engine Project Office cooling liner and sized to fit a To study the self-atomizing char- 178-kN thrust combustor has been acteristics liquid swirl elements.

133 Research and Technology 1993

The facility consists primarily of two A variety of diagnostic tools is avail- • High-speed film cameras (up to separate air regulators, a water accu- able for use at the ABP facility: 5,000 frames/s) for spray imaging mulator, an injector head, and a • Stroboscopic imaging of sprays, spray tank (fig. 94). The air regula- • Planar laser-induced fluorescence using a 1-]_s duration strobe. tors are dome loaders operated by (PLIF) imaging of sprays, using a hand valves. The air lines are 1.27-cm 5-W argon laser and rhodamine The APB facility is currently being stainless steel tubing. The water 6-6 dye used to study optical methods for measuring liquid phase mass distri- accumulator is simply a set of • Excimer-pumped dye laser for bution by making PLIF measure- 5.08-cm diameter stainless steel tubes instantaneous (15 ns) imaging of with a thickness of 0.1661 cm. The ments of swirl coaxial element flow high-speed sprays accumulator is pressurized with air fields. It was also recently used to from two separate 17,225-kPa K- • Phase Doppler particle analyzer study the effect of imposing a strong (PDPA) for measuring droplet size acoustic field on a thin liquid sheet. bottles. Maximum water pressure is distributions in sprays 3,445 kPa, regulated. For safety, a The HBP facility is presently under relief valve set to 3,790 kPa has been • Intensified and unintensified development. It will be used to com- placed in each output line. video cameras for spray imaging pare the atomization and mixing

PSIG RV-3 550PSIG Vent PT-1 PG-I HOV-1 1,500PSIG RV-1 i_ L soy-2 750PSIG SOY-! Air

i "_ WaterVen! DLR-1 Accumulator

RV-2 BalticI 550PSIG I SOV-3 PG-2 Fill Vent fltR-2 HOV-2 !,500PSIG r-- --

PG-4 DLR-2 5,000PSIG soy-4 [ SOV-S Spray CV-1 Air PT-2

HOV-2 Head CV-2 SleeveAir Injector PT-3 TC-I

WaterSupply

HOV-5 - WaterlOGPMPump ToDrain Fill ! AIMHead FIGURE94.--Arnbient Back Pressure Facility.

134 Technology Programs

by the angular momentum causes low-density chamber gases to flow into the lox post. Understanding this flow behavior is necessary to make predictions of injector performance, as well as to evaluate the element for injection-coupled combustion insta- bility. The AM facility uses water as a lox simulant to study these effects in cold flow, using clear models. Figure 95 is a photograph of the air core formed when testing a typical swirl lox post. The air core extends the entire length of the post. It becomes established at very low flow rates and, after becoming established, its shape remains independent of the flow rate.

Hutt, J.; Robertson, T.; McDaniels, D., Eskridge, R.; and Fisher, M. June 1993. Rocket Injector Single Element Characterization at the Marshall Space Flight Center. AIAA 93-2337.

Sponsor: Marshall Space Flight Center Director's Discretionary F_nd

FIGUR_95.--Air core in a Iox post. characteristics of shear and swirl The AM facility is a Center Director's coaxial injector elements at condi- Discretionary Fund project specifi- tions similar to the operating condi- cally designed to study some unique tions of the SSME preburners. The aspects of swirl coaxial injector objective of this study is to deter- elements. Typically, swirl coaxial mine if swirl elements could reduce elements involve swirling liquid the temperature striations that exist oxygen (lox) in a central tube. The at the turbine inlet. radial pressure gradient caused

135 Research and Technology 1993

Systematic Data flawed due to measurement system the optimization procedure is to Reconciliation in Rocket uncertainty. More importantly, indi- minimize adjustments in the engine vidual engine component models are variables from the initial test values. Engine Performance based on one-dimensional, uniform The PRM generates a set of perfor- Predictions flow-averaged conditions. Local mance predictions by reconciling test measurements in a complicated flow data with fundamental physical rela- .John P. Butas/EP14 network such as a rocket engine are tionships within specified uncertainty 205-544-7057 incapable of characterizing flow- limits. In effect, PRM predictions pro- averaged conditions with absolute vide the most plausible set of engine Technology-derived power balance accuracy. Computational predictions performance conditions, recognizing models are used to support the con- are forced to agree with the data at the inherent uncertainties in both ceptual design of rocket engines instrumented locations, often at the fundamental physical relations and and, ultimately, to correlate flight expense of satisfying the balance of test measurements. engine test data with previous ana- the fundamental physical relation- lytical predictions. The primary pur- ships (mass conservation, momen- The PRM has been under develop- pose of engine modeling technology tum, and energy conservation). If ment for approximately 2 yr and is js to provide an accurate assessment this occurs, the computed hardware currently being used to evaluate of the characteristics of the indi- characteristics no longer reflect the SSME performance. The PRM was vidual engine components prior to physical hardware, Consequently, used to analyze performance charac- and after experimental and flight use of the pristine data assumption teristics of the SSME oxidizer pre- engines are developed. These indi- can lead to inaccurate hardware burner (OPB) and high-pressure vidual components are modeled characterization and engine system oxidizer turbopump (HPOTP). Test using theoretical relationships which performance prediction. Such condi- data obtained from the Technology describe turbopump characteristics, tions could result in poor design de- Test-Bed (TFB) facility at MSFC pressure losses, and heat transfer cisions and inadvertently contribute were used to support the analysis. effects. These theoretical relation- to a catastrophic failure. A cursory uncertainty analysis was ships are adjusted to correlate them performed to determine uncertain W to test data. Thus, the quality and An effort is currently ongoing to estimates for both the engine mea- validity of the performance predic- develop performance analysis mod- surements, as well as the funda- tions generated rely primarily on the els that eliminate the shortcomings mental physical relationships. The process in which test data are inte- inherent in the assumption men- uncertainty analysis indicated the grated with the theoretical relation- tioned above. A new computational uncertainty band for pressures, ships. If this process is flawed, the model, termed the Performance Rec- temperatures, and flow rates to be hardware characteristics and perfor- onciliation Model (PRM), is a general approximately 6 percent of the mea- mance predictions generated from rocket engine performance analysis sured value, the mass balance uncer- these models will be inaccurate, tool with test data integration capa- taint,/band to be approximately 0.50 unreliable, and could steer the rocket bility. The solution procedure incor- percent of the total high-pressure engine development program on porates a system-level nonlinear oxidizer turbine (HPOT) flow, and a costly and undesirable course. mathematical optimization strategy. the energy balance uncertainty band Hence, technology-derived power The optimization strategy requires to be approximately 4 percent of the balance models are constantly being uncertainty estimates for both test total HPOT horsepower. measurements and the balance of upgraded and modified to meet the growing demand for new engine the fundamental physical relation- A volume analysis was performed on cycle analysis and development. ships. The optimization procedure the SSME HPOTP subsystem, using selects values for engine variables TYB test sequence 25 (TTB-25) test The assumption that measured test (flow rates, pressures, temperatures, data. The purpose of the volume data are absolutely accurate is im- speeds, etc.) within defined measure- analysis was to check the test data plicitly incorporated within the com- ment uncertainty limits, while satis- with respect to mass and energy putational strategy of most power fying the fundamental physical conservations. The results of the balance models. However, the so- relationships within defined balance analysis indicated a small mass called "pristine data" assumption is uncertainty limits. The objective of imbalance, but had a larger than

136 Technology Programs

SO the inlet and exit of the turbine. The PRM reduced the inlet HPOT temperature by 60 °R, which is ap- 4O [] proximately 4 percent of the mea- n surement inlet temperature. The PRM increased the discharge HPOT tem- & perature by 50 °R, which is approxi- ID 30

O mately 4 percent of the measurement Z discharge temperature, The PRM I,.- 20 UncertaintyUmit(higher) predicted 110 °R reduction in the Z HPOT temperature drop corresponds I i UncertoinlyHPOTEnergyUmitImbdance(lower) ,ID to approximately a 45-percent reduc- 10 tion in total HPOT horsepower. This 8 was the primary adjustment required ...... J_ .L to reduce the large energy imbalance observed within the measured TTB- 25 test data. Using one-dimensional t t flow assumptions, the computed -1(; I L I I I L I HPOT efficiency from the test data is 25 50 75 100 125 150 175 200 unrealistic. The computed HPOT T'..eIs) efficiency derived from the PRM predictions more closely matches FIGURE96.--SSME energy imbalance from TTB-25 test data. theoretical performance.

acceptable energy imbalance. Fig- temperature to reduce the energy The new PRM provides a systematic ure 96 presents HPOTP energy im- imbalance to within the acceptable procedure for incorporating uncer- balances with respect to the percent- uncertainty band. Figure 97 presents tain test data in computational proce- age of total HPOT horsepower. comparisons of PRM analysis predic- dures without corrupting physical Based on flow, pressure, and tem- tions and TTB--25 test data. The PRM balances beyond established and perature data, the HPOTP energy reduced the OPB total flow by ap- defined limits. This systematic proce- imbalance indicates that the turbine proximately 0.7 lb/s. This indicates dure is a more accurate method for is delivering approximately 45 per- the PRM predictions agree well with generating hardware characteristics. cent more horsepower than required the measured OPB venturi flow. In Results from the SSME subsystem by the pump. addition, the PRM reduced the tem- analysis indicate the adjustments perature drop across the HPOT by required to reconcile the TTB-25 A PRM subsystem analysis was per- approximately 110 °R, The HPOT HPOT flow rate and temperature formed on the SSME OPB and temperature drop computed from measurements with the physical HPOTP. The PRM was used to rec- TFB-25 test data is approximately relations within the PRM, The pre- oncile the TE13-25 test data with 240 °R. This HPOT temperature drop dicted 4 percent adjustment in the fundamental physical relations by is computed from individual ten> HPOT temperature measurements adjusting the HPOT flow and perature measurements at both could represent a delta between

137 Research and Technology 1993

OPBTml FI_ averaged and localized effects or 65 could represent coolant effects that are not currently modeled within 64 the theoretical relationships. Future analyses will be performed with better uncertainty estimates and 6a more detailed engine component | s2 models in order to further improve a engine hardware characterization. These types of measurement and hardware effects have been observed in the past and make it difficult to determine accurate hardware perfor- -- ReconciliationI _f mance characteristics. The PRM 59 I I I _ I I l provides a scheme to begin quantify- 0 25 50 15 100 125 150 175 200 ing these effects and improve the Time (s) engineer's understanding of the true flow environment within a rocket

tlPOTTemlxtrature Drop engine. This will ultimately improve 28O performance predictions and enable the PRM to be a more useful rocket 260 engine design tool. 240 Sponsor: Space Shuttle Main Engine 220 Project Office, Office of Space Flight 2OO University Involvement: Christian i180 Brothers University I O TestData 160

140 ReconciliolionI

I 1 I I 120 25 SO 75 100 125 150 175 20O Time (s)

FtGURE97.--Performance reconciliation model comparisons to 1-rB--25.

138 Technology Programs

High Mixture Ratio Core _8.8_cm-_1 _,

Gas..... Generator Analysis O/F1.0-H2_ 3"81_ _ 12"29cm 1 Huu P. Trinh/EP13 0/1:- __ 11.43cm 205-544-2260 O/F= 6'0--_ _::_1 '---_-'1 .j2.97cmI_eSplash An advanced gas generator (AGG) 0/F= 1.0_ [ [] rur_l,m 1 with a high mixture ratio core, which H21_- i • Ring 39.37cm m, has a potential use for future liquid I ,M rocket engines, has been studied. Because of the high mixture ratio FIGURE98.uSchematic diagram of a gas generator with core, such a generator can be ignited a turbulence ring and a splash plate. reliably during the start up. The gen- erator, therefore, can be used for the selection of mixing techniques are gas mixing. Therefore, this causes a no-bleed start operation, which has a based on the minimization of the nearly uniform gas temperature at low initial mixture ratio. Furthermore, radial temperature variation at the the gas generator exit. When a gas the hot temperature streaks, which generator exit and the generator generator is designed such that a are also experienced on current gas pressure loss. turbulence ring with the height of 2.29 cm and a splash plate with the generators, can be controlled and height of 2.97 cm are positioned at diffused by means of introducing The AGG geometry and operating conditions are the same as the 8.89 and 3.81 cm, respectively, enhancement mixing devices on the downstream of the injector face hot core gas generator. However, ad- baseline of the gas generator of the space transportation main engine (case 1), the gas temperature varia- ding the mixing devices would in- (STME) (Mercer and Hernandez tion is less than 6.0 °R at the exit crease the engine pressure loss and 1993). The study included the effects (fig. 99), with the pressure drop the engine complexity. of various mixing enhancement de- across the generator at 7,924 × 103 A number of combustion gas mixing vice geometries and various local Pa. However, if the turbulence ring techniques and mixing enhancement mixture ratios (fig. 98), while the height is reduced to 1.14 cm, and the devices, including hot gas core in- overall mixture ratio of the generator ring and the splash plate are posi- pingement, auxiliary diluent injector, is maintained. The results indicate tioned at 6.35 and 8.89 cm from the turbulence ring, splash plate body, that placing a turbulence ring and a injector face (case 2), the tempera- etc., are numerically simulated using splash plate with reasonable height ture variation at the exit increases up the existing reactive flow equation and at a proper location in the gen- to 60.8 °R, while the pressure could solver (REFLEQS). The criteria for the erator chamber could maximize the drop by as much as 2,412× 103 Pa.

139 Research and Technology 1993

0.06 Combustion Stability Testing and Analysis 0.05

0.O4 Marvin Rocker/EP13 205-544-4140 ( 0.03 $ The in-house developed code Fre- $ quency Response of Admittance of 0.02 $ Coaxial Injector Elements (FRACIE) is being used in conjunction with the 0.01 | Aerojet-developed high-frequency I | intrinsic (HIFI) code to predict com- 0 1 1 I 8OO 850 900 950 1,000 bustion instabilities in Rocketdyne's Temperature(K) 2-D Stability Research Combustor (2-DSRC). The FRACIE and HIFI codes are combined to form a con- FIGURE99.--Temperature distribution at exit. trol-theory-oriented model (fig. 100). The FRACIE-HIFI model has been The results also show that the maxi- Mercer, S.D., and Hernandez, R. February reasonably accurate in matching mum gas temperature at the genera- 1993. ALS Rocket Engine Combus- frequencies of chamber and injector tot exit decreases as the mixture tion Devices GGA Test Plan. Con- tract NAS8-38080 GGA Test Plan pressure oscillations exhibited in ratio at the hot core region moves DR-30. data obtained from a test firing of the from a stoichiometric ratio to the 2-DSRC. The FRAClE code models fuel-rich condition. In addition, the Sponsor: Office of Space Systems the acoustics of a shear-coaxial injec- maximum gas temperature at the exit Development tor given the total number of ele- is lowered by increasing the im- ments, element geometry, steady pingement angle of the hot core Commercial Involvement: propellant flow conditions, and pro- injector elements. Detailed results of Sverdrup Technology, Inc. pellant thermodynamic properties. this study are found in "Design Study Plans to upgrade the FRAClE code to of an Advanced Gas Generator," by model swirl-coaxial injectors are in Kim and Trinh, 1993. progress. The HIFI code models the acoustics of a combustion chamber Kim, S., and Trinh, H,P. June 28-30, 1993. Design Study of an Advanced given geometry, steady chamber Gas Generator. AIAA 93-2158, conditions, and combustion products AIAA/SAE, ASME/ASEE 29th Joint gas properties. Additionally, the HIFI Propulsion Conference and Exhibit. code models acoustic cavities given the total number of cavities, cavity geometry, and local gas properties. The Colorado State University-devel- oped RDORC code will be added to form a collection of codes that model chamber acoustics. The RDORC code has a more realistic combustion model and is currently being used by Rocketdyne in its combustion stability analysis.

140 Technology Programs

38.1 cm in width. The combustion LaxPostAcouslksand Oxidizer chamber is also serviced at the aft Po! (s) VaporizationDelay Combustion Gain end by 10 small nozzle-orifices about 1.778 cm in diameter. Testing, cur- --_t__ .._ _lf_yo/(s)e_.to, ! ,ir+_l Combustion rently in progress at the MSFC test Oxidize, / i= I Co ,, on aneto 1,1(s) stand 115, investigates the effects of Manifold CombustionResponseto I fhamberArousfirs Injeclor mixture ratio, chamber width, and Pc chamber pressure on combustion

Cham_r stability. Tests at 1.38 MPA/in e cham- ber pressure exhibited some pressure Manifold &P Is) oscillations both in the chamber and '_ffiYfi(s)e -szfi ! 2 injector. Tests at chamber pressures of 2.07 MPA/in e and 2.76 MPA/in" Pf' (s)'_ I [ i:l I _ Dislur_nce Com' t o. CNo ,I are in progress. High-frequency test VaporizationDelay Gain data were reduced to obtain domi- nant acoustic frequencies in the chamber and injector. Test data will FIGURE 100.--Block diagram of chamber-injector-combustion interaction. be used to verify current empirical correlations, formulate new correla- tions, and verify' the accuracy of the OxidizerInJet HIFI and FRACIE codes used to predict combustion instabilities.

Sponsor: Office of Aeronautics and EoaxialInjector Space Technology, Office of Ad- _ermocouple vanced Concepts and Technology

University Involvement: Colorado State University

Commercial Involvement: Rocketdyne, A I)ivision of Rockwell International; and Aerolet

£ ExhaustPorts

_llerBIocks

FIGURE 101.--Two-dimensional Stability Research Combustor assembly.

The 2-D Stability Research Combus- liquid oxygen/gaseous hydrogen tor Test Program is a joint effort (lox/GH,) subscale combustor sup- between MSFC and Rocketdyne to plied by up to 10 shear-coaxial investigate the mechanisms respon- injector elements (fig. 101). The sible for combustion instabilities in combustion chamber is rectangular liquid propellant rocket engines. The and is 26.67 cm in length, 2.54 cm Rocketdyne-developed engine is a in thickness, and is adjustable up to

141 Research and Technology 1993

Low-Cost and life cycle of turbomachinery. This in-house design will demon- Turbomachinery The objective of this turbopump strate the capability of a low-cost design, named "Simplex," is to mini- liquid oxygen turbopump via an Technology mize design complexity and to re- improved design and fabrication duce design and fabrication time process. The prototype will also Matthew W. Marsh/EP32 (fig. 102). The Simplex turbopump demonstrate a liquid oxygen pump 205-544-1773 will be powered by gaseous nitro- driven by an oxidizer-rich turbine gen or gaseous oxygen. This elimi- gas. Another benefit of this task is nates the need for an interpropellant Turbomachinery used in liquid the increased ability to estimate seal required to separate the fuel- the cost of rocket engine turbo- rocket engines typically are com- rich turbine gases from liquid oxy- posed of complex geometries made machinery. The turbopump design gen, which results in a simplified from high-strength-to-weight super- would be suitable for integration design. Materials used in the turbine with the hybrid motor, providing a alloys. These high-performance ma- flow paths will utilize existing char- warm-oxygen source from a tap-off chines usually have long design and acterized metals at 171 °C that are location. fabrication cycle times, typically 3 to compatible with a warm-oxygen 5 yr. These factors increase develop- environment. The goal for this de- ment time and result in high costs Sponsor: Office of Advanced sign is to complete the design and Concepts and Technology, Earth-to- for rocket engine turbomachinery. fabrication within 12 too. The cost Orbit Technology Office for the first unit fabrication and as- A simple, low-cost turbopump is be- sembly is predicted to be less than ing designed in-house to demonstrate $125,000. the ability to reduce the overall cost

\

PumpDischargePressure:10,343kPa MassFlowRate:41kg/s TurbineInletPressure:6,895kPa TurbineInletTemperature:171°C RotationalSpeed:25,000rpm

FIGURE102.--Simplex turbopump preliminary cross section. 142 TechnologyPrograms

Compliant Foil Bearing MSFC and Allied Signal Aerospace cryogenic liquid turbopumps. Allied Technology Company, Aerospace Systems and Signal's efforts have recently been Demonstration Equipment Division, have under- tested at MSFC as a result of a coop- taken a program to demonstrate the erative agreement. A 4.445-cm diam- capability of an alternative to the eter leaf-type compliant foil bearing Gary G. Genge/EP32 rolling element bearing. This alterna- has demonstrated a load capacity 205-544-4941 tive is a leaf-type compliant foil bear- and direct damping in liquid nitro- ing developed by Allied Signal (fig. gen and oxygen capable of support- For many years, rocket engine 103). For several years, Allied Signal ing a turbopump sized for an upper turbomachinery has relied on rolling has been using this type of hydro- stage engine. The testing was per- element bearings (i.e., ball bearings dynamic bearing in air cooling units formed with a bearing test rig de- or roller bearings) to support the used on many commercial airplanes. signed specifically for obtaining rotor system. These bearings worked However, the bearings required these data. satisfactorily for engine systems that several innovations to be able to were on expendable rockets because carry the much higher loads found in In addition to test rig work, MSFC the bearing life was limited to only a and Allied Signal have a second few starts and short operational time. cooperative agreement to demon- As the desire to have reusable long- strate the bearing in an actual liquid Foil life cryogenic turbopumps became oxygen turbopump. Allied Signal has Housing prevalent, the bearing system re- built a turbopump equivalent to a quirements for these machines be- turbopump needed on a 71,200---N came more difficult to attain. thrust engine, and MSFC will be testing this pump at the test stand FoilSegments The rolling element bearing is lira- 500 facility. The data will be col- Red by the rolling contact stresses I lected and the results published that cause fatigue and wear of the I I within a year. balls, rollers, and races. In order to Foil f Segment keep these stresses low, the turbo- hmeved Sponsors: Office of Advanced pump design often utilized a small Concepts and Technology, Earth-to- 1 diameter, more flexible shaft that Orbit Technology Office; and complicated the rotordynamic prob- Advanced Chemical Engines lems of the design. Recent efforts have been made to eliminate the Commercial Involvement: Allied rolling contact problems by support- Signal Aerospace Company ing the rotor on a film of fluid that Foil._ the turbopump is pumping. This led to research in hydrostatic and hydro- dynamic bearings that would elimi- nate the rolling contact fatigue and wear life issues, as well as allow the designers to enlarge the shaft diam- eters to simplify the rotordynamic design. FIGURE103.--Compliant foil journal bearing.

143 Research and Technology 1993

Low-Temperature Testing V,cuumLi_/ _0up_/ of Static Seals and L_k _tm0r HeliumSupply fleolerPower Leakage Characterization D Edward E. Litkenhous III/EP42 205-544-8387 // Heater // This test program has two objectives: (1) to create a data base on the per- formance of static seals at low tem- peratures, and (2) to characterize leakage rates for inert gases and correlate these rates with cryogenic _ GosbO-Seol propellant leakage rates. Both the Static Seals Test and Phase I (inert gas leakage) of the Leakage Charac- Heater terization Test will be performed using the same test fixture.

The Low-Temperature Static Seals Test will determine the actual perfor- mance of Viton TM elastomer Gask- O-Seals when exposed to tempera- FIGURE104._Static seals test schematic. ture conditions from ambient to -101.1 °C. Additional testing will be conducted on static O-ring seals of manufacturer data provide little an open drawer that is filled with several materials, including ethylene information of the material character- liquid nitrogen (LN 2) to a maximum propylene, fluorocarbon, and sili- istics of seals when exposed to low level of 5 cm above the top of the cone. temperatures. fixture. Kapton TM heaters are mounted inside the fixture to control The Viton TM elastomer Gask-O-Seals, There are two seal configurations to the temperature of the test article, used to seal the flanges of the He be tested. The first test configuration between ambient and -101.1 °C system of the SSME, are designed to is the Viton TM Gask-O-Seal currently (fig. 104). operate for the temperature range used in the SSME helium system. between -40 and +371 °C. The char- The second test configuration is for The test cycle will begin at ambient acteristics of this fluorocarbon seal the static O-ring face seal test. The temperature. The temperature will are satisfactory during normal space O-rings will conform to Parker size then be reduced in 11+3 °C incre- shuttle flight conditions. It has been number 2-022 (2.51+0.025 cm out- ments until the test article reaches noted that in special cases during side diamater, 0.178+0. 007 cm -101.1 °C. The test article tempera- reentry (-56.7 °C) or during a return- cross-sectional diameter). ture will then be increased in 11+3 °C to-launch site (RTLS) abort(-62.2 °C), increments until the test article the temperature of the seal could fall The test configuration consists of a reaches ambient conditions. The he- below-40 °C. At these low tempera- sealed fixture that contains two lium leakage rate will be measured tures, the Viton TM Gask-O-Seal may bolted flanges that are sealed with continously throughout the cycle. lose much of its ability to stop leak- either Gask-O-Seals or O-rings. The age. Currently this condition is cov- inside surface of the seal will be The Gask-O-Seals will be tested first, ered for the SSME by a change to pressurized to 5.86 MPa with gas- and the amount of compression Interface Control Document (ICD) eous helium (GHe). The outside applied will not be varied. The 13M15000, which increases the al- of the test seal will be held in a flange compression of the O-ring lowable seal leakage rate. Static seal vacuum. The fixture is placed inside seals will be varied to determine if

144 Technology Programs

increased compression will improve A very small orifice will be used to thermally soaked for a minimum of the ability to maintain a seal at low simulate a leakage path. The test 10 rain at ambient conditions. The temperatures. This compression will media will be chosen to correspond temperature will be reduced in incre- be varied using shims. Three O-ring as closely as possible in temperature ments of 14+10 °C until the test fix- seal materials were chosen to be and physical properties with the in- ture reaches -195 °C. The leakage tested, four O-rings for each material tended propellant, initially using GHe rate will be recoded at each incre- and each compression level will be and GN2 and later expanding to per- ment. The test fixture temperature tested. The compression of the static form propellant leak testing. The will then be increased in 14 °C incre- seal O-rings will be varied from 10 to flow formulae will be given in volu- ments until the test fixture reaches 40 percent, in 10-percent increments. metric form, and the gas formulae ambient conditions. After this test will be expressed in units that are a cycle, the pressure will be regulated The Low-Temperature Static Seals product of pressure and volumetric to 690 kPa and the test cycle re- Test will provide a data base of the flow; e.g., atm-cm3/s. peated. If additional data are desir- properties of static seal materials able at other pressures, then the test when exposed to low temperatures. The leakage path will consist of an cycle will be repeated. Identical tests This data base will contain informa- orifice plate welded to the flanged will be run for additional orifice sizes tion useful for determining candidate end of the static seals test fixture. not to exceed 0.38 mm in diameter. materials in future low-temperature The inside surface of the test article seal applications. will be pressurized to 345 kPa with The Leakage Characterization Test GHe. The outside of the test article will provide a correlation between The Leakage Characterization Test will be held in a vacuum. The fixture propellant and inert gases. By using will provide an experimental correla- the correlation, designers will be tion between the leakage rates for will be submerged inside an open able to reduce the amount of testing inert gases and the leakage of pro- drawer filled with LN,. A heater will be mounted to the fixture to vary the done with propellant gases. Using pellant. This will be accomplished by nonvolatile substitutes will decrease subjecting these inert gases to vary- temperature of the test article be- cost by increasing safety. ing temperatures and measuring the tween ambient and cyrogenic tem- leakage rates through an orifice of a peratures. The leakage rate will be ttord, J. Correlations for Estimating Fluid known size, while varying the tem- measured at ambient conditions, Leakage. May 19-22, 1968. American perature of the gas from ambient to originally to verify comparison with Institute of Chemical Engineers cryogenic. GHe and gaseous nitro- empirical data and to verify that (AIChE), and Instituto de lngenieros there is no leakage elsewhere in the Quimicos de Puerto Rico, Joint gen (GN) will be used initially Meeting Second Symposium on (Phase I), and later testing (Phase II) test setup. Leakage rates will be measured using a helium mass spec- Cryogenic Advance in the Space will include propellant leak testing. A Program, AIChE preprint 9E. trometer or a flow meter capable of correlation will be developed for the Tampa, FL. measuring a range of 0 to 16,400 leakage of H e and 02 . The test fixture standard cmUmin. designed for the static seals test will Sponsor: External Tank Program, be modified for use in this test series Office of Space Flight The first test series will be conducted (fig. 105). with an orifice size of 0.15 mm in Commercial Involvement: diameter and a supply pressure of Sverdrup Technology 345 kPa. The test cycle will be initi- ated after the test fixture has been

F_GURE105._Static seals test fixture. 145 Research and Technology 1993

Electromechanical two permanent magnet brushless High-Power Propellant Control motors, dual-channel control elec- Electromechanical Thrust Valve Actuator tronics, and special sensors for rate Vector Control Actuators and position feedback. The actu- ating mechanism is shown in figure Martha B. Cash/EP34 106. The mechanical and electrical Rae Ann Weir/EP34 205-544-4282 interfaces are such that the unit is 205-544-7146 functionally interchangeable with the Electromechanical actuating mecha- currently used hydraulic actuation Current launch vehicles, including nisms for operation of propellant mechanism. the space shuttle orbiter and solid flow control valves are being devel- rocket boosters, use hydraulic-type oped for the next generation of pro- systems for providing engine thrust pulsion systems and launch vehicles, vector control. Hydraulic fluid power as well as potential replacements for systems are mature technology; how- existing hydraulically operated actu- ever, their servicing and maintenance ating mechanisms. Alternatives to requirements are such that the costs fluid power systems would poten- associated with these operational tially reduce operational costs associ- systems are significant. This, along ated with system fabrication, launch with the need to maintain stringent fluid cleanliness to minimize par- operations, and maintenance and ticulate contamination, make for refurbishment costs of maintaining relatively expensive systems. precision fluid systems necessary to minimize contamination-related New control mechanism technologies anomalies. are currently being developed to FIGURE106.--Electromechanical provide alternatives to the fluid propellant valve New control mechanism technologies power systems now in use. Develop- actuator. are currently being developed to pro- ments in rare Earth permanent mag- vide alternatives to the fluid power net motors, high-power switching systems now in use. Developments Initial testing has been completed, devices, and electrical power sources in rare Earth permanent magnet and results are very promising. Les- of competitive weight and volume, motors, high-power switching de- sons learned have resulted in a make electromechanical thrust vector control mechanisms viable candi- vices, and electrical power sources change to the control electronics in of competitive weight and volume order to meet the positional rate and dates for the next generation of launch vehicles, as well as potential make electromechanical propellant accuracy requirements for the SSME. flow control mechanisms viable can- replacements for existing vehicles Additional testing will be done to and systems. didates as potential replacements for assess the overall suitability for func- existing vehicle propellant flow tional verification on a Technology control mechanisms. A prototype configuration thrust Test-Bed static firing. These addi- vector control (TVC) actuator has tional tests will be vibration, thermal, been designed and is currently un- A high-fidelity prototype actuating and other environments, as well as mechanism has been designed and is dergoing thorough evaluation and functional verification in the engine operational characterization testing currently undergoing preliminary simulation laboratory facility. performance and characterization (fig. 107). The unit is driven by two 19-kW three-phase permanent mag- testing. This unit is a dual-redundant net motors driving a two-pass spur mechanism designed to meet all $1_nso_: Office of Advanced Concepts and Technology gear system. This in turn drives a operational performance require- roller screw device that converts the ments for use on the SSME. It utilizes rotary motion into linear motion. The roller screw device, as well as all other mechanical components, are of a robust design capable of generating high forces on the order

146 Technology Programs

Multipurpose Hydrogen test and operational experience is Test-Bed rather limited. The foam thermally protects the tank from ground-hold/ ascent flight environments, and en- George R. Schmidt/EP25 ables use of a dry nitrogen purge as 205-544-6055 opposed to a traditional, yet heavy and complex, helium purge sub- The development of high-energy system. It consists of a 1.3-cm thick cryogenic upper stages is essential Isofoam SS-1171 layer bonded to the for the delivery of the large payloads tank wall as shown in figure 108. envisioned in future programs. A key The multilayer insulation (MLI) ele- element in such spacecraft is cryo- ment provides protection in the genic fluid management (CFM) tech- FtGURE107.--MSFC 50-hp TVC space vacuum and is designed for eiectromechanical nology. In response to this expected an on-orbit storage period of 45 d. actuator. need, MSFC is conducting a develop- It consists of a double aluminized ment effort involving full-scale, Mylar TM (DAM) blanket with an aver- ground-based testing of integrated of 178,000 N. Sensors provide rate age layer density of approximately CFM subsystems for space transpor- and position feedback for closed- 10 layers/cm and is composed of 40 tation applications. The approach is loop control. to 50 radiation shields with coarse to develop and utilize a systemqevel Dacron TM net spacer material. Unique The control electronics use pulse test-bed, termed the Multipurpose features of the MLI concept include a width modulation (PWM) technol- Hydrogen Test-Bed (MHTB), which variable distance between the shields ogy. Insulated gate bipolar transistors will be representative in size and to reduce weight and fewer, but are used as the high-voltage, high- shape of a fully integrated space larger, perforations for venting during current power switching devices. vehicle liquid hydrogen propellant ascent to orbit. The electronic controller is rated at tank. approximately 27 kW. Electric power is supplied by a battery bank of lead- Major objectives of MHTB thermal The MHTB tank, which wasdelivered control tests are to: { 1) establish-- acid-type batteries, configured to to MSFC in December 1992, is 3.05 m provide 270 V at 100 A. through hands-on experience-- in diameter, 3.05-m long, has an design and installation techniques Initial testing has been completed, 18.09-m _capacity, and is made from for FMLI in full-scale applications, and results are very promising. Les- 5083 aluminum. The tank is designed (2) define thermal performance and sons learned have resulted in a to accommodate a varieW of differ- operational constraints during expo- change to a single-pass gear system, ent thermal control, pressure control, sure to ground-hold environments, as well as changes to the controller and liquid handling subsystems, (3) prove that the MLI can be suc- design and feedback sensors. Addi- either individually or simultaneously. cessfully evacuated to full-vacuum tional testing on this prototype unit Major accommodation features in- conditions during ascent and orbit is planned. In addition, a four-motor, clude several fill, drain, and vent injection phases, and (4) establish 45.6-kW unit has been designed and ports; a 61-cm diameter opening for on-orbit performance of the FMLI is being fabricated. This unit will bulk access; sensors for liquid level, concept. A major goal of the ground- incorporate redundancy similar to liquid temperature distribution, and hold testing is to ensure that the flight systems now in use and will ullage pressure; internal mounting foam external surface temperature is also be subjected to a rigorous test brackets for future equipment; and maintained at or above 116 K to program culminating with engine low-heat-leak structural supports. gimbaling during a static test firing prevent gaseous nitrogen liquefac- on the Technology Test-Bed engine tion. Also, saturation of the MLI with facility. The first phase of MHTB testing will dry nitrogen must be ensured to pre- evaluate performance on a foam/ vent frost buildup. The on-orbit Sponsor: Office of Space Systems multilayer insulation (FMLI) thermal evaluation will include definition of Development control system (TCS). Although this steady-state thermal performance concept offers a significant advan- with minimum and maximum [] tage for ground-based upper stages, MLI surfacetemperatures of

147 Research and Technology 1993

modification or changeout of TVS components without entering the tank. In the mixing mode, fluid is withdrawn from the tank by the pump and flows back into the tank through a spray bar positioned along the tank's longitudinal axis. Fluid expelled radially through the spray bar circulates and mixes tank con- tents regardless of liquid position, thus ensuring destratification and suppression of pressure rise. When pressure relief becomes necessary, a portion of the circulated liquid is passed sequentially through the expansion valve and spray bar heat exchanger element, and finally vented to space. The vented vapor cools the fluid circulated through the mixer element and removes thermal energy from the bulk liquid. In a low-gravity transfer application, the spray-bar concept could also be used to assist tank refill. By filling through FIGURE108.uMHTB tank following partial application of Isofoam SS-1171 spray-on foam. the spray bar and heat exchanger, the inflowing fluid would be cooled and used to mix tank contents, there- 140 and 300 K, respectively. A system- The second phase of MHTB testing by accomplishing a "no-vent fill" level thermal computational model, involves demonstration of an ad- process. verified by MHTB testing, will enable vanced thermodynamic vent system definition of heat-leak contributions (TVS) for tank pressure control and A Critical Design Review (CDR) for through each penetration and the zero-gravity venting. The concept the MHTB zero-gravity vent was FMLI. selected for MHTB differs from more successfully held in late June 1993. conventional designs in that the Hardware delivery at MSFC is sched- active components (i.e., Joule- uled for the spring of 1994, with MSFC is currently installing the TCS Thompson expansion valve, pump, testing to begin in 1995. in-house. All foam application was and isolation valve) are located ex- completed in April 1993. Layup of ternally in a stainless steel cylindrical The third phase of MHTB tests ad- the barrel and dome MLI sections, enclosure attached to the bottom of dresses pressurization techniques which is shown in figure 109, was the tank. This approach allows the needed to support engine startup finished in September 1993. Testing pump to operate without adding and general liquid expulsion/ is scheduled to begin late in 1993. heat to the propellants, and enables transfer. Although considerable

148 Technology Programs

Combined Foam/ Mulfilayer Insulation Demonstration

George R. Schmidt/EP25 205-544-6055

The propellant thermal control requirements for ground-based up- per stages and servicing systems" are unique. The thermal control system must operate effectively in all mis- sion phases, namely ground-hold, launch/ascent, and orbit-hold, and provide thermal protection in both convection- and radiation-dominant environments. In convection-domi- nated or pressurized environments, a spray-on foam insulation (SOFI) that reduces heat conduction to the tank wall is usually selected. This ap- proach is implemented on launch vehicles, such as the space shuttle external tank, and ground storage facilities. In space, a blanket consist- FIoURE 109.--Bottom view of MHTB tank following layup of multilayer insulation around barrel section. ing of very thin radiation shields separated by a low-conductance fabric is used to reflect radiation im- experience with cryogenic pressur- In-house design and fabrication of pinging on the outside of the space- ization systems exists, pressurization the pressurization system hardware craft. The problem is that either form collapse due to liquid remaining on is complete. Testing will be con- of insulation by itself is inadequate the walls following a propellant ducted concurrently with MHTB for a spacecraft that must function in resettling maneuver is still a concern. thermal control and zero-gravity both environments. Also, in several orbital transfer sce- vent subsystem tests. narios, pressurization with unsettled One promising solution is to imple- propellants may be required. Based Sl:_Onsors: Office of Space Systems ment the two insulation concepts on the preceding considerations, the Development, and Office of Ad- simultaneously in one system. This MHTB pressurization subsystem vanced Concepts and Technology combined foam/multilayer insulation includes provisions for evaluating concept is currently being investi- both gaseous hydrogen and helium gated to assess its performance in pressurants at various temperatures simulated flight environments. The and flow rates. The MHTB pressurant experiment apparatus, which is inlet diffuser is based on the design shown in figure 110, consists of a used with the space shuttle external tank. subscale, insulated liquid hydrogen

149 Research and Technology 1993

1,000

FMLIGround CentaurG-Prime [] (LeRC)Ground SalurnIVB

. 100

1banCentaur2andS 4_ CentaurG-PrimeOrbit A FMLiOrbit 87in O M_BO_

lOSino t O.l J * , i , i i,I I m i ii*I * i i , , ,,, 100 FiOURE1 lO.--Test tank installed in 1,000 10,000 I00,000 1,000,000 the 20-fl vacuum Stomp Volumeof Tank(L) chamber. 1.000 tank installed in the MSFC 20-ff FMLIGround 13 IV8 diameter vacuum chamber. The Smm CentaurG-PrimoGround • environment within the chamber is I00' varied to simulate the pressure his- tory and temperature within the MHTBGround shuttle cargo bay during ground- hold, rapid ascent, and on-orbit hold. = IO Results will be compared to flight TitanCentaur2and5 data from the shuttle ET and Centaur 4, FMLIOrbil rocket upper stage, and analytical i CentaurG-primeOrbit results from a systems improve numerical differencing analyzer (SINDA) computational model. Upon MHTBOrbit completion of tests, the insulation will be removed and thoroughly lO n o.1 , i I Imll'l I * 1 111111 I I I IllllJ ¢ ' i iilll l I I I I Ill examined to assess the effect of 0.1 1 10 100 1,000 I0000 repeated operational cycling. Testing MissionDuration(H) will aid in determining the feasibility of employing the combined insula- SurfaceAren/Yo/ HotBomdary(K) InsulationContent tion concept on a reusable, wet- 0.37 155 InternalFoam launched upper stage. It will also 0.59 144-311 provide a means of validating ana- MylarTM (1layer)andDoublyAluminizedMylarTM (DAM)(2layers) A 030 222 lytical models for various launch FoamPanels(2-by-19ram)endDAM¼tl(3layers) 0.86 277 environments. 0 Goklized KaptonTM MLI(20lolms) 0 0.63 294 DAMMLI(70layers) 1.60 166-255 To date, four ground-hold simula- [] SOIl(10.2ram)DAMMLI(16layers) 0.57 166-300 tions have been performed while SOFI(25.4mm)DAMMLI(45varhd_/spacedlayers) maintaining the vacuum chamber and environmental shroud under FIGURE1 1 1.--MHTB steady-state ground and orbit-hold a gaseous nitrogen purge. boil-off losses compared with other programs.

150 I Technology Programs

Total average heating rates ranged Fluid Acquisition and Demonstration (SFMD), which was from 752 to 882 W for shroud purge Resupply Experiment carried aboard STS 51-C in January flow rates of 0 and 0.079 kg/s, re- 1985. The FARE hardware was spectively. This yielded propellant mounted in five orbiter middeck George R. Schmidt/EP25 loss rates ranging from 8.8 to 10.4 lockers as shown in figure 112. Four 205-544-6055 percent of the tank volume/h. Re- of these contained the hardware, suits also indicated that the foam while the fifth provided space for Propellant and fluid tankage operating surface temperature, which varied stowage of a flowmeter display, vent in a low-gravity environment re- from 172 to 189 K for the aforemen- hose, and cables. The test fluid was quires methods for acquiring and tioned purge rates, was sufficiently deionized, distilled water with food expelling vapor-free liquid. In addi- high to prevent liquefaction of coloring and a wetting agent added. tkm, any orbital resupply and replen- oxygen and nitrogen. Test operations entailed transferring ishment must be performed without fluid between two transparent acrylic venting liquid or exceeding tank Three steady-state orbital hold and tanks. The receiver tank, which was pressure limits. Liquid acquisition heating simulations have also been videotaped during the experiment, devices (LAD's) that exploit surface performed. Electrical heaters installed contained the LAD, while the supply in the environmental shroud allowed tension are Wpically used to separate tank contained a bladder to ensure and orient liquid in the tank. Al- application of several warm bound- expulsion and recovery regardless of though both screen and vane LAD's ary conditions during each test. Aver- initial liquid orientation. have been successfully used in flight age insulation heating rates during applications, performance limits orbit-hold simulations ranged from remain undefined. For example, the 3.1 to 8.2 W for boundary tempera- space shuttle's Orbital Maneuvering tures of 167 to 256 K, respectively. System (OMS) uses screen channel These rates corresponded to liquid LAD's, but the performance limits losses of 0.9 and 2.3 percent of the and design margins cannot be estab- tank's volume/d. lished during flight. Similarly, a vane LAD was used on the Mars Viking In June 1993, the test program con- cluded with four ascent tests. It will orbiter, but its low-graviW perfor- take several months to disseminate mance margins were never verified. and process these data, which in- clude transient estimates of heat The purpose of the Fluid Acquisition loads and boil-off losses. The results and Resupply Experiment (FARE) is obtained so far from ground- and to demonstrate the performance of a orbit-hold tests appear to confirm the screen and vane LAD aboard two FMLI concept's flexibility in handling different shuttle flights, The test ob- pressurized and vacuum environ- jectives include: (1) evaluating and ments, as shown in figure 111. How- comparing the expulsion efficiency ever, the volume percent loss rates of both designs, (2) assessing how were higher than flight data for each well each LAD orients the liquid and insulation type in its respective de- maintains surface stability during sign environment. This is because vented fills with different inflow FIGURE1 12.--Testing of fill perfor- of the full-scale application's de- rates, and (3) determining the re- mance through screen LAD aboard STS-53. creased surface area-to-volume ratio sponse and rewicking capability compared to the test tank. A more of the devices when subjected to consistent comparison will be pc)s- various orbiter accelerations. The first flight tested the screen de- sible once full-scale FMLI tests are vice, and consisted of eight experi- conducted in 1993, using MSFC's FARE successfully flew on mission ments examining different values Multipurpose Hydrogen Test-Bed. STS-53 in December 1992, and on of inflow rate, expulsion rate, re- Sl_nsor: Office of Space Systems STS-57 in June 1993. The facility was ceiver tank pressure, and imposed Development originally built by Martin Marietta acceleration. Besides vide(), data as the Space Fluid Management included 35-mm still photography,

151 Research and Technology 1993

the liquid would wick back to its Liquid Acquisition Device original position within 10 to 15 s. Characterization This demonstrated that the screen channel was relatively immune to acceleration. George R. Schmidt/EP25 205-544--6055

The second flight tested the vane In the absence of gravity or large device and basically repeated the accelerations, channels and traps conditions examined on the first comprised of fine-mesh screens are flight. At the time of this report, used to foster liquid expulsion from videotape data from the second had spacecraft tankage. Operation of not been processed. However, a such devices with storable propel- real-time downlink enabled prelimi- lants is well understood and has FIGURE| 13.--Closeup of LAD tank nary observation and evaluation by been demonstrated in numerous during expulsion tests the experiment's investigators. The applications. Designing these com- aboard STS-53. results indicated that the expulsion ponents for use with cryogens, how- efficiency for the vane was approxi- ever, is complicated by the fact that crew comments, and recorded accel- mately 95 percent. Although this was the fluid is stored at or close to a erations from the orbiter's micro- somewhat less than that for the saturated state. Thus, mass, heat, and gravity acceleration measurement screen, the vane appeared to be momentum transport between the system. more effective in stabilizing the sur- liquid, screen, and pressurant gas face and better suited for liquid con- The results indicated that the screen can destabilize the liquid/gas inter- trol during the vented fill process. was highly effective in expelling gas- face between the screen pores (i.e., The most notable aspect of the free liquid from the tank under a meniscus), and cause vaporization vented fill tests was the astronaut's and retention loss around the screen. varie W of conditions. A photograph abili W to adjust the inflow to the of the receiver tank during expulsion critical Weber number. At this point, through the screen LAD is shown in The objective of this project is to the geyser emanating from the inlet figure 113. In all expulsion tests, an research the underlying thermo- jet reached its maximum penetration expulsion efficiency of 96.5 to 98 per- physics governing retention of into the ullage bubble without break- cent was achieved. However, the screened acquisition devices with ing through. This value has been vented fill tests were not as conclu- cryogenic propellants and to im- estimated before from previous sive. It appeared that interfacial sta- prove the understanding of how analyses and drop-tower experi- such phenomena influence the sur- bili W and fill percent was maximized ments, and the FARE results, once at a Weber number (ratio of inertia face stability and maximum sustain- processed, will provide another data to surface tension forces) of 2.3 or able pressure difference across point to evaluate its validity. between the minimum and maxi- simple screen-weave geometries. mum tested of 0.6 and 5.2, respec- Rather than assessing performance tively. It was also found that Sponsor: Office of Space Systems of a particular device, the project whenever an adverse acceleration Development focuses on effects at the screen-pore was applied, regardless of whether level and involves computational the tank was 5- or 50-percent full, modeling and experimental observa- tions of two-phase fluid behavior near the liquid/gas interface.

152 Technology Programs

superheated and subcooled meniscus k SIeamfunction Magnetically Actuated bounded by isothermal sidewalls. Propellant Orientation This study provided useful insight into the physics of the flow field and served as a validation against the George R. Schmidt/EP25 205-544-6055 results from previous investigations. Figure 114 shows the steady-state In a low-gravity environment, acqui- stream function and isotherm (i.e., sition of vapor-free propellant is constant temperature) profiles for the complicated by the indeterminate three types of regimes considered in location of bulk liquid with respect the study. Note that either the sepa- to the tank outlet. Proper design of rate or simultaneous action of inter- engine feed or propellant transfer facial flow and/or thermocapillary systems requires methods to control SidewallSubcooling/Condensation stress produces distinct velocity and liquid orientation and an understand- temperature distributions. An impor- ing of fluid motion in response to tant result was that the interfacia] Sleamfunction disturbances and imposed accelera- heat transfer for all three regimes tions. Traditional approaches for was greater than the case for a sta- controlling and positioning cryogenic tiona W fluid. liquids, such as period thruster fir- ings and capillary retention devices, The results of this study have exhibit several drawbacks that could pointed to several causes for liquid be mitigated by employing systems acquisition device retention failure. that exploit the inherent paramagne- It appears that evaporation and tism of liquid oxygen and diamagne- -OIl condensation, in conjunction with tism of liquid hydrogen. With the thermocapillary flow, exhibit oppo- advent of lightweight, high-tempera- site trends in terms of influencing ture superconductors, and high-flux surface stability and bubble-point density, rare Earth magnets, the use of magnetic fields to control large SidewallSuperheating/Evaporation pressure. That is, condensation tends to foster instability, while evapora- fluid quantities in microgravity ap- tion tends to suppress it. In the small pears feasible, and could enable low- F_GURE1 14.--Steady-state flowfield, pores considered here, all convec- gravity settling, venting, filling, and temperature, and tion modes can cause a notable de- acquisition without the need for meniscus. viation from the hydrostatic solution capillary retention systems or propul- for meniscus curvature due to tem- sive firings. Some of these potential A major accomplishment was the perature-dependent variation in sur- applications are shown in figure 115. development of a model that pre- face tension, vapor recoil, and This project is currently evaluating dicts combined thermocapillary, dynamic pressure along the surface. the feasibility and practicality of evaporation, and condensation flow These effects have not been fully magnetically actuated propellant in an isolated rectangular cavity. It studied yet, but will be the emphasis orientation (MAPO) for spacecraft also accounts for meniscus deforma- of future analytical and experimental applications. The scope has been tion and all tile thermo-physical activity. phenomena relevant to retention of a restricted to lox primarily because: (1) control of lox offers the near- volatile liquid. The model was ini- tially used to investigate the com- Sponsor: Marshall Space Flight term application of MAPO technol- bined influence of thermocapillarity, Center Director's Discretionary Fund ogy, (2) the magnetic properties of evaporation, and condensation on paramagnetic fluids are well known, the flow and heat transfer about and (3) [ox behavior has been tested before in a low-gravity environment on a laboratory scale. One of the primary objectives is to determine the range of magnetic field strengths required to perform reorientation 153 Research and Technology 1993

Scaling analyses have shown that Magne! magnets in the size range of 1 to 10 raramagnetk_"_, Tesla should be adequate for propel- lant reorientation in a full-scale lax application. These results, however, are rather limited since the fields can Fluid(Lox) typically assume very complicated geometries, which are difficult to Magnet-_ characterize in terms of dimension- less groupings. Consequently, an- other aspect of this activity is focused on modifying an existing computational fluid dynamics (CFD) model to include the body and sur- face forces arising from the interac- tions between the fluid and magnetic field. This will provide a more rigor- ous means of assessing fluid behav- ior, and will enable the modeling of Rearientationand Tank Fill Long-TermIn-Space more complicated field geometries Expulsion Storage and advanced concepts, such as liquid hydrogen. Videotaped record- FIGURE115.--Potential applications of magnetically actuated ings of fluid motions taken from the propellant control for spacecraft. low-gravity tests will be used to validate the revised CFD model. and maintain liquid orientation dur- be ready for preliminary tests in Sponsor: Marshall Space Flight 1993. Two other series of tests will ing tank fill and expulsion. This Center Director's Discretionary Fund range will provide a basis for evalu- be conducted in 1994. ating whether these magnetic field requirements fall within the capabili- ties of current or anticipated super- Free-FloatingExperiment Facility-ProvidedN2 conducting magnet technology. Two-Direction

The project involves low-gravity experiments utilizing the KC-135 nel low-gravity aircraft. All experiments employ the subscale hardware _i egulolor shown in figure 116 and a noncryo- genic ferrofluid, that simulates the paramagnetic behavior of lax. The ferrofluid is a commercially available kerosene-based solution containing a suspension of extremely fine ferrous particles. Several properties of this fluid (i.e., particle density, viscosity, and surface tension), along with tank diameter, flow rates, and magnetic [_ PressureReliefValve 'Y_ FlexHose field intensities, are being scaled to model lax behavior in a spacecraft- [_ Hand-OperaledValve [-- QuickOisconned type application. Design and assem- [_ SolenoidValve (Z) PressureGaoge bly of the test article is nearing StorageRack completion, and the facility should FIGURE11&--Schematic of KC-135 testapparatus. 154 Technology Programs Structures and Dynamics III I II

Computer Aided Grid accomplished by developing the and extremely time consuming. Interface System computer aided grid interface (CAGI) Geometry-grid generation is consid- system. The CAGI system is being ered the most time- and cost-critical developed by integrating computer part in a typical CFD application. Theodore G. Benjamin/ED32 aided design/computer aided manu- There is a need to develop a cost- 205-544-9402 facturing (CAD/CAM) geometric effective and efficient computational system output and Initial Graphics geometry-grid generation capability NASA maintains an applications- Exchange Specification (IGES) files applicable to complex geometries oriented computational fluid dynam- (including all NASA-IGES entities), encountered in propulsion problems ics effort complementa W to, and in geometry manipulations and genera- at MSFC, and one that is timely support of, aerodynamic propulsion tions associated with grid construc- enough for engineering design; this design and test activities. This is tions, and robust grid generation is the motivation for the current especially true at MSFC where the methodologies. CAGI development. This project was goal is to advance and optimize initiated on May 16, 1992, with the present and future liquid-fueled commitment to release a version of rocket engines. Numerical grid gen- A multitude of techniques and com- software each year. eration plays a significant role in the puter codes have been developed fluid flow simulations that CFD uti- for generating computational grids in lizes. An overall goal of the current arbitrary regions. However, in most CAGI is being developed in a modular project is to develop a geometry grid of these codes and methodologies, fashion. A self-explanatory pictorial generation tool that will help engi- the evaluation of the geometry input view of different modules and their neers, scientists, and CFD practition- and realization of mapping between linkage is provided in figure 117. The ers to analyze design problems physical and computational space computer languages FORTRAN 77 involving complex geometries in a allowing appropriate zonal/block and C in a UNIX window environ- timely fashion. This goal is being strategies are long, very laborious, ment are utilized for portability.

NumericalVisualizationFlow XXXXXXXXX XXXXXXX t e4_

Sarfa¢e CAGI Generation

Geometry Geometry Surface IGES Transformer ManipulationSystem Maaipulatiom

G_phics

OtherCAD/CAM Systems ] UserInterface i I t CommonlyUsed _, Geometry I ConfigurationsLibraryof I I DataFacilityBase i

FIGURe117._CAGI modules.

155 Research and Technology 1993

geometric information. An example representing a complex impeller con- figuration is presented in figure 118. In figure 118, the surfaces interpreted by the IGES transformer are pre- sented using a CAGI graphical user interface; the pictorial view of the grid behavior is presented in the graphics window.

A scientific workstation-based, user- oriented, menu-driven software sys- tem, CAGI, that will aid in geometry preparation and establishment of zonal boundaries/surfaces for com- plex grid generation applications encountered in present and future liquid-fueled rocket engines is being developed. The progress to date has indicated that this system will help FiGure 118.--CAGI user interface: surfaces created by IGES transformer for CFD practitioners analyze design impeller data. problems involving complex CAD/ CAM-generated geometries in a An X-based interface is provided, of these developments in surface timely fashion. allowing Silicon Graphics, Inc. (SGI) grid redistribution, adaptation, re- Graphics Language (GL) library of mapping, and optimization are being Blake, Matthew W., and Chou, Jin J. X-graphics access by command-line explored. The work continues on April 1992. The NASA-IGES Geom- etry Data Exchange Standard. Pro- argument. The dynamic allocation of the development of multiblock strat- ceedings of a workshop sponsored memory and linked lists on a well- egies and the geometry manipulation by the NASA, Langley Research defined data structure is allowed in system, along with the develop- Center, Hampton, VA. the CAGI development. A module, ment of the NURBS tool kit for grid an IGES transformer, is developed generation. Vu, T.Y. August 1992. IGES Transformer allowing all critical geometrical enti- and NURBS in Grid Generation. ties. All NASA-IGES geometric enti- The initial (Beta) version of the CAGI Master's thesis, Mississippi State ties have been considered in this system offering an IGES transformer, University. development. The nonuniform ratio- conversion of the geometric entities nal b-spline (NURBS) curve/surface/ into the standard NURBS data struc- Yu, T.Y., and Soni, Bharat K. April 1993. w_lume representation is selected ture, and various geometry manipu- Computer Aided Grid Interface for the geometric description. The lation and generation, was released (CAGI). Computational Fluid Dy- NURBS offers a control-point based to MSFC personnel in June 1993. The namics Workshop, NASA, MSFC, AL. parametric representation that is IGES transformer module was incor- widely utilized for interactive de- porated in the grid system GENIE++ Sponsor: Office of Advanced Con- sign applications using CAD/CAM and the National Grid System being cepts and Technology systems. An inverse formulation of developed at Mississippi State Uni- NURBS is developed for evaluation versity. The current version of the University Involvement: of control points associated with the CAGI system has been applied to Mississippi State University sculptured discretized specification of various grid generation applica- geometrical entities. The application tions based on the IGES-supplied •

156 Technology Programs

Analysis of Residual ///// ///// Flexibility Modal Test Data

PauIS. Bookout/ED26 k: I 205-544-1490

MichaelL. Tinker/ED26 3.66m 205-544-4973 i1

Historically, fixed-base testing has 4.44cm been used for verification of space shuttle payload models. Due to diffi- [_ ...... 1"[I_ AluminumPtote culties involved in the fixed-base _k_ I (0.476-cmthick) approach, free-free modal testing AluminumPlate augmented by residual flexibility (3.175cm2× 0.476cml_ BrassScrew (0.3175-cmdia.) measurements has been studied and, to a limited degree, applied in the model updating process. The pur- FIGURE119.--Beam test article. pose of the current research effort is to implement the procedure in-house beginning with a simple beam hav- or the value of a displacement/force • Extraction of experimental re- ing a trunnion simulator attached residual function at zero frequency, sidual functions by subtracting an (fig. 119). By using a very simple approximates the higher-order FRF containing only the measured modes from the full measured structure, high confidence should modes that are not measured in the FRF exist in the model, allowing the free-free test. Constrained-boundary study team to focus on the accuracy modes of the payload are calculated • Comparison of experimental and of residual measurements. Successful using the measured free-free modes analytical residual functions to and residuals. measurement and calculation of assess measurenlent accuracy. residual flexibility for the simple In applying the residual flexibility Implementation of the residual flex- beam is to be followed by test and method to the simple beam, a num- analysis for a more complicated ibility technique for the simple beam with trunnion simulator consisted of ber of problems were encountered in structure. The final phase would obtaining values for residual terms likely involve use of actual payload the following steps: from measured residual functions. test data, after which the approach An analytical residual function in the would be available as an alternative • Development of a finite element displacement/force domain has the model procedure when fixed-base testing characteristics of a relatively fiat line proves undesirable. a Measurement of free-boundary in the lower frequencies and sligl_t frequency response functions upward curx'ature in the higher fre- Modal test procedures for the residual (FRF) from which vibration mode quency range. In the test residual function, the above mentioned char- flexibility approach involve the mea- shapes and frequencies are ob- surement of free-free modes as well tained acteristics can be seen, but due to as the residual functions for the struc- the present limitations in modal ture interfaces or boundary degrees • Updating of the model to improve parameter estimation, the residual of freedom. Residual flexibility, agreement with test frequencies function has regions of ragged data.

157 Research and Technology 1993

lOIo A second-order polynomial curve fit is required to obtain the residual flexibility and residual mass terms. As stated previously, the residual ..... CurveF'_ ---.... WeightingResidualFunctionFunctionI flexibility term is computed by evalu- ating the residual function at zero frequency, while the residual mass term is determined by the upward lOI curvature of the residual function. Direct curve fits of the test data pro- duce poor results due to the ragged data regions. A method of reducing the effect of the ragged data upon the curve fit process is necessary. A weighting function, which will re- duce the effect of the ragged data, is generated by examining the vari- ances between neighboring data points. Due to the characteristics of the residual function as stated above, 2O 40 60 80 100 120 140 160 180 200 the variance of the data should be Frequency(Hz) small throughout the frequency span. The ragged data produce large vari- ances. Taking the inverse of the IOl variance, the weighting function is produced. From a weighted second- order polynomial curve fit, an accu- rate residual flexibility value can be obtained (fig. 120). The residual I0o flexibility value and test free-free modes are used to update a math- ematical model of the structure.

Admire, J.R.; Tinker, ML.; and lvey, E.W. April 13-15, 1992. Residual Flexibil- iWTest Method for Verification of Constrained Structural Models. Pro- ceedings of 33d Structures, Structural Dynamics, and Materials Conference. 10-2 Pp. 1614--22. Dallas, TX.

Rubin, S. 1975. Improved Component Mode Representation for Structural Dynamic Analysis. AIAAJout_zal 13:995-1006. I0-3 0 2O 40 60 80 1O0 120 140 160 180 200 Sponsor: Space Station Project Frequency(Hz) Office

FIGURE120.--Weighted curve Fit, with (top} and without (bottom) weighting function plotted.

158 Technology Programs

Investigation of Inducer of acrylic, allowing 4.5 ,6 Cavitation and Blade high-speed photogra- 4.0 q., Loads phy of the inducer 33 cavitation patterns. As 3.0 4g. suspected, the inducer 2.5 Wayne J. Bordelon, Jr./ED34 exhibited alternate 2.0 3i 205-544-1579 blade cavitation, caus- 15 ing a two-times syn- 1.0 During hot-fire development testing chronous (2N) forcing 03 t of the alternate turbopump develop- function at a certain 0 ' ment (ATD) lox turbopump, the lox suction-specific speed 4,000 8,000 12,000 16,000 20,000 24,000 pump experienced high pump-end (Nss). However, an SuctionSl ifk Speed(Nss) vibrations, causing engine shutdown. unexpected finding It was determined that the pump was revealed that this 2N FJOURE122.--ATD Iox pump inducer shroud water experiencing high rotor vibrations at cavitation mode would flow dynamic pressure data. super-synchronous (above shaft suddenly shift to a speed) frequencies that would sud- synchronous (1N) cavitation mode at The lox pump vibration investigation denly shift to a high synchronous a higher Nss condition. As revealed summarized above prompted re- (shaft speed) frequency. The prob- by high-speed film and measured newed interest in turbopump inducer able cause of these high vibrations dynamic pressures (fig. 122), there cavitation and the resulting rotor was determined to be a fluid-struc- was a sudden drop in the 2N pres- loads. To further investigate the tural coupling between the inducer sure amplitude followed by a sudden various inducer cavitation modes and cavitation and the rotor system. increase in the 1N amplitude. This quantify the rotor loads, an effort has cavitation mode change is believed been initiated at MSFC to retest the As part of the effort to solve this to be a significant contributor to the ATD lox inducer with improved flow problem, full-scale water flow in- sudden increase in pump vibration. visualization access, additional in- ducer tests were conducted at MSFC. Testing of five inducer configurations ducer housing measurements, and The test article (fig. 121) was instru- revealed that although this 1N on-rotor dynamic pressure and strain mented with accelerometers cavitation mode could not be measurements. The objective of this and dynamic pressure eliminated, the amplitude could effort will be to: (1) develop ad- measurements and SSM[ be substantially reduced by vanced testing and analysis methods was, in part, made PumpSupply increasing the inducer tip for studying inducer cavitation and Dud clearance--the eventual "fix." unsteady blade loads, (2) identify unsteady and destabilizing cavitation modes, and (3) quantify the non- cavitated and cavitated inducer blade BypassDud hydrodynamic loads. This effort is expected to directly benefit the ATD program in the short term and re- duce the cost and risk to future turbopump development programs in the long term.

Sportsors: Office of Advanced Con- cepts and Technology, and Alternate Turbopump Development Project Office De-swirlVanes TotalPressure KielHeadAssembly Inducer

FfGURE12 1.pMSFC inducer technology rig cross section. 159 Research and Technology 1993

Bosch Reaction Kinetics (temperature, feed composition, etc.) Cylinder Optimization of Research to identify operating conditions Rings, Skin, and Stringers where the thermodynamics for the Bosch reaction are unfavorable. Robyn L. Carrasquillo/ED62 Several catalysts including nickel and Jeffrey L. Finckenor/ED52 205-544-7227 205-544-7041 iron were then studied for transient rate effects at different temperatures Patrick R. Rogers/ED24 Recovery of O z from CO a is essential and as carbon is deposited on them. 205 -544-4632 to enable closure of the 0 2 loop in Nickel was found to be a strong Neil E. Otte/ED24 the space station Environmental methanation catalyst at lower tem- 205-544-7231 Control and Life Support System's air peratures, but did not significantly revitalization subsystem. A promising decay in activity. Two iron catalysts method that was evaluated is the Cylinder Optimization of Rings, Skin, were studied; both exhibited an and Stringers (CORSS) is a computer Bosch reactor. Improvements in the initial rate drop followed by a sharp program written to optimize the reactor design are needed to make increase to levels comparable with this method more suitable. preliminary design of stiffened shells nickel. Activity degradation occurred of skin-stringer construction. A com- on iron, but was less severe on iron The objective of this project was to mercially available optimization pro- investigate the reaction kinetics oc- supported on gamma-aluminum gram called Design Optimization Tool (DOT) is linked to a skin- curing in the Bosch CO 2 reduction oxide (AIaO_). The most significant finding in these studies was that subsystem reactor-furnace to obtain a stringer analysis. The analysis uses under none of the conditions studied quantitative rate expression based on closed-formed solutions and engi- was the testing able to produce fila- catalyst quantity, reactor tempera- neering design equations. DOT calls ture, and constituent concentrations. mentous carbon as seen in all proto- the analysis to evaluate the weight type Bosch subsystems. The carbon This rate expression would then be and limitations of a given configura- formed was amorphous, having a used for analytically modeling the tion and iterates to find, numerically, Bosch subsystem, which would lead much higher inherent density than the minimum weight design. filamentous. Finally, a steady-state to optimizing the Bosch process ef- ficiency. A secondary objective was reaction rate expression was devel- At the beginning of the National to identify alternate catalysts or en- oped relating rate of carbon dioxide Launch System (NLS) program, a reacted to partial pressures of con- hancement to the present catalyst skin-stringer construction was baselined for much of the vehicle. providing improved reaction rates, stituents and reaction temperature. This expression will be used to en- Since there would be a number of reduced startup time, and reduced hance phenomenological models of catalyst degradation. design cycles, CORSS was written to Bosch subsystems. enhance the turnaround time and A thermodynamic computer model accuracy of the primary structure was developed to investigate the dif- Sponsor: Office of Space Systems designs. ferent regions of operating conditions Development

160 Technology Programs

The analysis was written in the "C" language and linked to the DOT FORTRAN code. The opti- "-W mizer varies the stringer dimensions r (h, _a, tst) (fig. 123); the number of stringers (Nst); and the skin thick- ness (t). The failure modes consid- _,,_ h_l alpha ered are skin buckling, shell buck- ling, allowable stress, stringer crip- -f " --- X pling, and stringer local buckling. Figure 124(a) shows a typical opti- i r mization history of normalized design Area03 '_,, variables. Figure 124(b) shows the history of the constraint values. For ._. _.a__/'--tt ' DOT, a negative value means the constraint is satisfied. The variation Hat-Stringer of the values by DOT and the effect of the changes on the constraints W can be clearly seen. The general decrease in weight during the opti- mization is also apparent. Depending on the initial conditions, run time Area2 "_ varies from 6 s to 1.5 min.

['2 Extensive use of CORSS was made t' 1 during the NLS project. It was ap- --_ Ist plied to every major component of h the 1.5-stage vehicle and the 9,100- kg-payload (20,000 lb) vehicle, two- 1 AreaO-- _ stage, NLS--3 vehicle. CORSS can be - I -_X applied to any stringer-stiffened shell I I t...... A-'-,_Z.L ..... made of an isotropic material. This could include tanks for the railroad I-Stringer or trucking industries, farm silos, and so forth. FIouRE 123.--Stringer dimensions.

161 Research and Technology 1993

CORSS is a practical application of optimization theory to real-world uses. It provides an easy to use, efficient design tool that links the analysis of a skin-stringer construc- tion with a numerical optimizer. It allows a large variety of different designs to be evaluated quickly and easily allows limits, such as those from manufacturing facilities, to be included. All the major failure modes are checked.

Bruhn, E.F. 1973. Analysis and Design of Flight Vehicle Structures. Jacobs Publishing, Inc.

Timoshenko, S. 1936. Theory of Elastic Stability. Engineering Sciences Mono- graph. McGraw-Hill. 0 1 2 3 4 S 6 7 8 9 10 11 12 13 Iteratio_ Vanderplaats, G., and Hansen, S. 1985- (hi 88. Design Optimization Tool. VMA Engineering. 0.50 Sponsor: Office of Space Systems , Weight Development

0.25 1 I Commercial Involvement: Martin Marietta Corporation 0

p_kJ_"/'L°ca'BucklingC'ol;mn['_r,_ p "h_'_'`-j_ _ -0.25

_nerol C¢imlorBuckling -0.50

S_tg55

-0.75 - _ ___ - = Cripple

I I I I ,J, I l I l I l I I -1.00° I 2 3 4 5 6 7 8 9 10 11 12 13 Itor_ion

Figure 124.--Normalized design variable history (a) and design constraint history (b).

162 Technology Programs

Optimum Design of the best solution. Thus, the optimum calculations. Second is a manage- Launch Vehicle Structures vehicle is better than that of a vehicle ment system to govern the variables combining independent optimum being passed back and forth. All elements. variables must be accounted for as Donald B. Ford/ED52 they are changed. Third is a set of 205-544-2454 The framework to perform the analysis modules to compute values analysis consists of three components for each variable. Each module rep- Recent launch vehicle design activities (fig. 125). First is a numerical opti- resents the function of a design team and current trade studies emphasize mizer to control the change of the within a given discipline. The frame- the need for both quick turnaround design variables. Any one of several work allows fast low-fidelity calcula- time and the ability to evaluate syn- public or commercially available tions to be interchanged with more ergistic effects of multiple design routines can perform the necessary intense analysis routines. variables. A computer tool that can transform preliminary design data into an optimally feasible vehicle i ] Avionic Aerodynamics Cost Design reduces the initial detail design time. J MechanisrmandFluid MSFC, in a joint agreement with General Dynamics, is developing a tool to size major launch vehicle structural elements, such as propel- Guidance lant tanks and intertanks. Numerical Optimizer Minimizing the total mass or maxi- mizing the performance are two StructuralDesign main approaches of launch vehicle design. Numerical optimization tech- niques manipulate multiple design variables to arrive at the global opti- mum point within given constraints. ThermalControl ThermalDynamics Performance WindsandControl Linking modular computer programs from several disciplines to a numeri- cal optimizer is the basic framework for the development effort. Incre- VariableManagement _ Functionol [---1 PotentialI mental results from each analytical module influence the overall vehicle as the design is driven to converge at FIGURE125.--Design tool framework.

163 Research and Technology 1993

ConfigurationAerodynamic Load AppliedLinearLoadModel - 0 System for Anomaly Model Model Model and Failure Detection

Thomas H. Fox/ED14 205-544-1462

Since ground testing of the SSME _k \ \ N e° , _ ,e began in 1975, there have been 36 , , i major incidents. These failures oc- curred despite an extensive internal

k system of self-checking and measure- ment redlines designed to safeguard the SSME. This number almost seems \ , 4 / insignificant when compared to the over 1,500 tests made without major incidents. However, these failures have costs associated with them that belie their small numbers. These ',x include costs from engine damage, stand damage, analysis costs, engine component loss, loss of failure evidence, and schedule impacts.

FIGURE126.--Iterative design cycle. An analysis of these failures showed that most of them could have been detected earlier than the present The recent NLS study provided a Combining the expertise of separate SSME redline method, with improved configuration to benchmark the disciplines with the speed of com- observability of engine operation. All design tool capability. A test case puters benefits the design process, the SSME failures were examined to successfully ran with the current as well as the design. The result is determine which engine measure- functional modules and provided a useful in three ways. It allows a ment, or suite of measurements, working platform to add potential vehicle concept to be quickly evalu- would indicate deteriorating SSME modules. An iterative cycle uses ated. It enables a variety of variables operation and incipient engine fail- ground winds, maximum dynamic to be traded against each other. It ure. It was found that almost all of pressure, and maximum acceleration also provides an accurate starting the engines involved in these failures conditions to establish loads and size point for a detail design activity. The could have been shut down earlier the major structures of the launch design cycle proceeds faster and than redline-initiated shutdowns. A vehicle (fig. 126). This initial single- produces a better total product. small list of generic failures types configuration tool is being further was ascertained that covered these developed to handle a variety of Sponsor: Office of Space Systems 36 failures. Work was initiated to vehicle configurations. Individual Development develop an algorithm for the detec- modules are already being used in tion of incipient engine failure dur- the detail design of hardware. Both Commercial Involvement: General ing the steady-state engine operation aerospace and other industries can Dynamics as a first cut. This algorithm has apply this approach to any design effort. since been improved to include monitoring the nonlinear portions of engine operation.

164 Technology Programs

Work has also started to extend TABtE6.--SSME simulated actual and hypothetical failures--stand tests monitoring to transient engine opera- tion. This last improvement should be implemented in 1994. A ground- based computer system containing the System for Anomaly and Failure 26 No Firstmonitoredtest Detection (SAFD) algorithm has, to 27 No Fulldurationtest date, monitored 17 hot-fire tests on the Technology Test-Bed stand at 3 28 Yes Lackd compensationformixtureratioshift MSFC. This system has also hosted 4 29 No Fulldurationtast other engine health monitoring algo- rithms during a part of this series of S 30 No Redlinecutmodeat5.3s(goodtest) tests. The ground-based system can 6 31 No Fulldumtiontest run the algorithms in a stand-alone 7 32 No Fulldurationtest mode or in parallel with other algo- rithms. The system has the capability 8 33 No Fulldurationtest.Hydrostaticbeatingtest to delegate engine shutdown author- 9 34 No Fulldurationtest.Hydrostaticbearingtest ity to a selected set of these algo- rithms. Those algorithms not selected 10 35 No Fulldurationtest.Hyclrostoticbearingtest would be in a passive monitor mode 11 36 No Pro.andWhitney(P&W)high-pressurefuelturbepump(HPFTP) only. 12 37 No P&WHPFTP The SAFD algorithm has been tested against a mixture of successful and 13 38 No P&WHPFTP failed tests using a combination of 14 39 Yes Largethroatmaincombustionchamber(MCC).Firstinstancecheckerror simulations and tapes of real, hot-fire tests. In all cases, the SAFD algo- 15 40 Yes LargethroatMCC.Firstinstancecheckerror rithm showed an improvement over 16 41 No LargethroatMCC.P&Whigh-pressureoxidizerturbopump(HPOTP) red-line methodology by issuing significantly earlier shutdown com- 17 42 No LargethroatMCC.P&WHPOTPandHPFTP mands (tables 6 and 7), except in the cases where catastrophic failures occurred.

Slmnsor: Earth-to-Orbit Technology Office, Office of Advanced Concepts and Technology Comsnercial Involvement: Rocketdyne, A Division of Rockwell International

165 Research and Technology 1993

TABLE7.--Other tests Cold Air Flow Turbine Testing of Advanced Turbine Designs

750-175 116.06 116.06 Hig_essureoxidizeduct Stephen W. Gaddis/ED34 205-544-1612 750-285 223.50 212.48 Feedline

3 901-173 201.17 201.02 Maininjector;alsorunatCanogaPark,MD The SSME alternate turbopump development high pressure fuel 4 901-183 $1.00 50.35 Maininjector turbine test article (TTA) was config- 5 901-225 255.63 255.61 Mainoxidizervalve ured with state-of-the-art aerody- 6 901-284 9.88 7.14 ContTolle namic design concepts and tested with the MSFC cold air flow turbine 7 901-340 405.50 295.42 HPFTP test equipment (TIE). The test pro- 8 901-364 392.16 386.00 HPFTP,venting/repressurization gram was a cooperative endeavor between MSFC and Pratt and 9 Nominal 901-511 -- -- Whimey's commercial and govern- 10 901-551 -- -- Nominal ment divisions. Testing evaluated turbine aerodynamic performance Runfo_UnitedTechnologiesReseerchCente(UTRC), 11 901-558 and provided results to validate vari- ol9o_hmsonly,fullduration ous CFD codes used during the design process. 12 901-577 RunforUIRC,nlgorithmsonly,high-pressureoxidizer turbine[ffPOT)totaldischargetemperature(TDT) The MSFC TYE is a cold air flow 13 901-683 Nominal blowdown facility that operates by HffTP,venting/rep_essurizol_on;Cono_Pork,MO; expanding high pressure air from 14 902-249 450.57 350.32 HuntsvilleSimula'_onLob 2.9 MPa (420 lb/in 2 gauge) to atmos- 15 902-398 -- -- Nominal pheric conditions. This equipment can deliver air for run times from 16 902-428 204.12 190.00 Oxidizerprebumeinjector,venting/repressurizelion 30 s to over 30 min, depending on 17 902-461 -- -- Runtodevelopo statisticalbose test conditions. The 3WE can accu- rately control and measure pressures, 18 902-462 -- -- Runmdevalopasmtisficolbose temperatures, shaft speed, torque, 19 902-471 147.68 146.16 (]m,flexjoint and horsepower. Full-scale test articles can be tested at scaled per- 20 902-463 -- -- Runtodevelopasta_ticalbase forrnance conditions accurately mea- 21 902-$19 -- -- Nominal suring pressures, temperatures, gas path flow angles, blade tip clear- 22 902-532 -- -- Nominal ances, dynamic pressures, and gas 23 902-149 109.86 109.78 FacilityaccelerationredlineonHPOTP path velocities by hot-wire or laser 24 OTM -- -- Hypo_tkolWebumepumpd_hmgeduct velocimetry.

25 DTM -- -- HypotheticalHPFTdischargeflowblock The test included the original Note:AsituationatN_ne0215intest901-666sbowKItheashatdowncornmealissueclonly0.38s_rmr_n _ r_m _ _ baseline two-stage, axial-flow ATD he_a'_dtds_rdicammgimduMge. fuel turbine "ITA with modifications.

166 Technology Programs

TurbineExit VaneClocking InstrumentationRakes Mechanism

Stage2 Vanes

Stage1Vanes

Air Flow

F_GURE127.--Cross section of vane clocking turbine test article.

A mechanism was included in the 54 first stage vanes, instead of the efficiency at the design point. Results test article design that allowed the 52 vanes in the original baseline test. from the advanced design features first stage vane assembly to be ro- Thus, first stage vanes were aligned incorporated in this test program are tated circumferentially in relation to relative to the downstream second applicable to aircraft engines, liquid the second stage vanes. Matching the stage vanes to determine the perfor- rocket engines, and land-based number of first stage and second mance effect of the first stage vane turbomachinery. stage vanes in the test article incor- wake interaction with the down- porated an advanced design concept stream vanes. The test results were SlmnSOr: Office of Advanced called vane clocking (fig. 127). The compared to the baseline test yield- Concepts Technology test article was configured with ing a 0.5 percent increase in turbine

167 Research and Technology 1993

Pump Computational against test data to verify their appli- first of its kind for a rocket engine Fluid Dynamics Code cability and to obtain a measure impeller. The data have been used to Validation Tests of their accuracy. Under this task, assess seven CFD codes currently detailed velocity measurements are being used by either industry, aca- made at several stations in the flow demia, or the Government, The ex- Roberto Garcia/ED32 path of selected pump components perimental results and some of 205 -544-4974 for comparison with the CFD the code comparisons have been predictions. published. A significant amount of performance data exists for many pump types. The SSME high-pressure fuel The second component tested under Empirical models have been created turbopump impeller was chosen as this task is a conventionally designed using the existing data, and it is the first component to be tested, It impeller that was optimized using these models that have been used to was chosen because it represents CFD. Despite having 50 percent as design pump components. Advances the state of the art in impeller design many blades as the SSME impeller, in pump design have been made by and performance. Laser velocimeter this impeller was predicted to have extrapolating from past experience, measurements were made on a increased performance and de- which inherently leads to increased 1610 grid at the impeller inlet that creased distortion. Therefore, this developmental risk. The use of com- was used by the CFD analysts as the test was conducted to verify the putational fluid dynamics codes in upstream boundary condition in their performance of a design arrived at the design process can reduce the models, Similar data grids were ob- using CFD. The data show that the risks associated with advancing tained at three radial planes down- velocity field and, hence, perfor- pump designs. However, before CFD stream of the impeller. Also obtained mance were very well predicted by codes are applied in the design pro- were pressure measurements on the CFD (fig. 128). Furthermore, the cess, they must first be benchmarked stationary walls. This data set is the comparisons for this impeller

Meridionolvelocitydistributionattheimpellerexit RelaliveflowangleatIheimpellerexit 20.0

30.0

10.0 20.0

.min- i 0 i,o.:

-I0.0 -10.0 ...... CFDAnalysisWithoutCavity ...... CFD_alysisW'_outCav'dym , e-_ - 4 TestCI:DDataAnalysisWithCavity i ,, - -e lestData l

I I I -20.0 I I i 0 O,S 1.0 1,5 -0,5 0 0.5 l.O 1.5 RelativeX RelativeX

FIGURE128.--Impeller CFD analysis comparison to data.

168 Technology Programs

showed that while the average per- Hydrodynamic Design This task has focused on centriflLgal formance of an impeller is not af- of Advanced Pump pump impellers as the pump compo- fected by details of the geometry nent that could most readily benefit Components downstream of the impeller (such as from the applications of CFD in the a sudden expansion cavity), the design process. As a demonstration distribution of performance from hub Roberto Garcia/ED32 case, a conventionally designed 205-544-4974 to shroud is significantly affected. impeller was optimized using CFD (fig. 129). A comparison of the re- The data collected under this task The design of pump components has suiting impeller design and the SSME have demonstrated the applicability not significantly changed over the high-pressure fuel turbopump shows of CFD codes for the design of cen- last 30 yr, while their operational that this new impeller has nearly the trifugal impellers. Presently, similar requirements in rocket engines have same efficiency as the SSME impel- data are being collected for a typical increased. Today's rocket engine ler, but does 11 percent more spe- rocket engine pump inducer. That designs are requiring higher specific cific work and its discharge flow experimental work will be followed work pumps and lower dynamic field has 12 percent less distortion. by _he acquisition of diffuser data. loadings, while maintaining high Furthermore, the new impeller has efficiency. These requirements can- 50 percent less blades than the SSME Brozowski, L.A. et al. May 8-11, 1994. not be easily met using conventional impeller, making it less expensive to Impeller Flow Field Laser Velocime- design practices without incurring produce. Subsequent testing of this ter Measurements. To be presented increases in development costs. new design confirmed the CFD at ISROMAC-5 Conference, Under this task, MSFC is applying predictions. Kaanapoli, Maul, HI. CFD tools to the design process to produce higher performance Brozowski, L.A. et al. June 20-24, 1993. pump components with reduced Laser Velocimeter Measurements of developmental risk. an Impeller Flow Field. Presented at the ASME Fluids Engineering Confer- ence Second Pumping Machinery Symposium, FED, Washington, DC. 154:187-96.

Prueger, G.H. et al. June 28-30, 1993. Validation of Computational Fluid Dynamic Analysis of a Rocket Engine Turbopump Impeller. AIAA 93-2575. AIAA/Society of Automo- tive Engineers (SAE)/American Society of Mechanical Engineers (ASME)/American Society of Electri- cal Engineers (ASEE) 29th Joint Propulskm Conference and Exhibit, Monterey, CA.

Sponsor: Office of Advanced Concepts Technology

FIGURE129.--Conventional design optimized using CFD: increased performance and reduced distortion.

169 Research and Technology 1993

Elastic-Plastic Fracture Mechanics Methodology for Surface Cracks

M. Wayne Gregg/ED27 205-544-5501

Pressure vessels are an essential part of all propulsion systems. Failure of one of these vessels can be a cata- strophic event resulting in the loss of millions of dollars, or human life. In order to ensure the safety of pres- sure vessels, safe-life analyses are often performed to ensure a flaw- tolerant design. In particular, pres- sure vessels of interest to NASA must comply with MIL-STD--1522A, Stan- dard General Requirements for Safe Design and Operation of Pressurized Missile and Space Systems. However, pressure vessels are often used in operating conditions that produce FIouRE 130.-- CFD-developed advanced impeller concept: significant plastic stress fields in increased performance and uniform flow the vicinity of the flaw. Because (white streak lines indicate the path taken MIL-STD-1522A does not account by fluid particles). for nonlinear stresses and is quite limited to the shape and growth The next step was to apply the new The optimization of the convention- characteristic of flaws, a research understanding on centrifugal impel- ally designed impeller and the ongo- effort has begun to establish a meth- ler flows that were acquired during ing advanced concept evaluation odology whereby pressure vessels the optimization of the first impeller have demonstrated the advantages may be designed to account for to the design of impellers incorporat- of using CFD in the design process these effects, ing new geometric concepts (fig. and have advanced the design of 130). Concepts evaluated included centrifugal impellers. The next step Under the direction of a MSFC tandem blades, blade lean, reposi- under this task is to make similar research grant, the Georgia Institute tioned partial blades, and tailored advances for the design of pump of Technology is performing testing chordwise loading distributions. The diffusers. and fractography in an attempt to final design of this advanced concept develop an acceptable methodology impeller is pending, but results ob- Sponsor: Office of Advanced for predicting "leak before burst" tained thus far show that leaning the Concepts and Technology (LBB) in pressure vessels subjected blades leads to further distortion re- to elastic-plastic fracture. In doing so, ductions (and, hence, lower dynamic three major tasks are to be accom- loads) for the same specific work, plished: without sacrificing efficiency. • The study of constraint and thickness effects in different specimen sizes and geometries

• The study of 3-D effects

• The development of a method- ology to assess LBB. 170 Technology Programs

Resistance curve testing of Inconel Elastic-Plastic and By incorporating the reference stress 718-STA1TM and AI 6061-T651 is cur- Fully Plastic Fatigue method, along with modifications to rently under way to obtain curves Crack Growth existing linear elastic fatigue crack that represent the energy required to growth data, J-integral solutions are grow the crack and to obtain fracture being formulated to allow quick surfaces so that constraint and thick- M. Wayne Gregg/EO27 solutions for crack growth problems. 205-544-5501 ness effects may be measured. A pre- The objectives of this research are to: liminary assessment indicates that • Review the literature and collect High performance demands placed some flaw shapes do not grow self- existing solutions for the J-inte- upon launch vehicles and propulsion similar, but instead tend to mush- gral, along with how the J-integral elements ultimately create an envi- room beneath the surface, thereby has been used for fatigue crack ronment in which components expe- giving a false measure of the crack growth predictions length. Leak-before-burst calculations rience stresses beyond the elastic on such flaws using the current regime. Life-prediction methods are • Develop and verify new solutions method would erroneously predict a needed to allow engineers to assess for the .j-integral for geometries of leak, whereas a burst situation may the longevity of these components interest to the SSME program exist. In order to determine how 3-D under such conditions. Currently, • Collect information from previous effects create changes in crack exten- knowledge about how flaw growth research efforts about crack clo- sion, 2-D specimens are being occurs is limited primarily to operat- sure and develop schemes to tested. ing conditions that produce stresses incorporate this information into in the elastic range. There exist, the estimation of governing pa- Planar specimens have been observed however, some independent solu- rameters for elastic-plastic crack to generate different fracture resis- tions in the literature for prediction growth tance curves when different thick- of cyclic plastic fatigue crack growth. nesses are tested. Because 3-D stress These solutions are generally ob- • Develop and verify algorithms ff)r fields are present in planar configu- tained via testing or finite element calculating elastic-plastic fatigue rations, mapping the crack face sepa- modeling and are valid only for a crack growth life under variable load histories and combined load ration profiles at different locations particular geometry and a defined set histories throughout the cross section should of boundary conditions. In order to produce parameters that can be obtain a practical method for predict- • Develop and verify algorithms generalized to the 3-D cases of inter- ing flaw growth in the plastic regime, that account for time and tem- est. Several specimens have been an empirical or analytical model is perature effects tested, and characterization of the needed that gives an acceptable • Develop damage rules for creep crack fronts is currently under way. solution for a range of boundary contributions to crack growth conditions. The research being conducted for • Develop and verify algorithms to this grant will result in an increase Southwest Research Institute (SWRI) predict the onset of final crack of the fundamental understanding instability is currently working under contract of how surface cracks grow in the for MSFC to develop analytical • Incorporate the algorithms and plastic region for a varie W of crack models for fatigue crack growth new J solutions into a usable shapes and sizes. More importantly, predictions in the plastic range. software package. however, the knowledge gained will be an invaluable addition in ensuring the safe operation and design of pressure vessels.

Sponsor= Earth-to-Orbit Technology Office, Office of Advanced Concepts and Technology

University Involvement: Georgia Institute of Technology

171 Research and Technology 1993

Several J-integral solutions have been different fatigue crack closure behav- Advancement of Volute collected along with a few newly iors. Most specifically, the maximum Design Techniques developed ones of interest to the stress does not correlate the effect of SSME. In particular, a closed-form different geometries on the crack Lisa W. Griffin/ED32 equation for the deepest point of a opening stress. This result indicates 205-544-8972 semielliptical surface crack in a finite that a parameter other than the maxi- width plate has been developed mum stress is needed for describing Traditionally, volutes have been using the reference stress approach. the crack opening stress over a range designed with limited analysis and a A comparison between finite element of geometries. After further investiga- solutions and the reference stress tion, it was discovered that the nor- heavy reliance on an existing data estimate for J shows good agreement malized stress intensity successfully base. This method of design has not with published results for a variety of correlates crack opening stresses for always been successful for rocket different crack depths, crack shapes, the three different specimen geom- engine turbopumps due to their and material constitutive relation- etries at three different crack lengths. complex flow paths and high pres- sures. Problems that can be encoun- ships. Currently, work is in progress The usefulness of the stress intensity to explore the applicability of the approach to characterizing crack tered by poorly designed volutes are general methodology to other spe- closure is readily apparent when low performance and high side loads cific geometric configurations. considering the complexities and that have to be reacted by the bear- time involved in modeling many ings in both turbines and pumps. In order to enhance the state of the art In addition to obtaining results for geometries and load configurations. new J-integral solutions, an appre- in volute design and to mature com- ciable amount of work has been As work continues on elastic-plastic putational fluid dynamics tools that completed on the contribution of fatigue crack growth, there is no have not been widely used for vo- crack closure on fatigue crack doubt that even more useful results lute analysis, the Turbine Technol- growth. Most of the previous re- will be brought forward. Once the ogy Team has initiated an advanced search on fatigue crack closure has algorithms are coded into a user- volute development program. The been for center cracked panels, with friendly software package, this new team is in the process of designing a few studies having been performed technology will enable engineers to an inlet volute and an exhaust mani- on the single-edge cracked plate in more accurately predict the life of fold system for the Gas Generator bending, and the compact tension components that experience non- Oxidizer Turbine (GGOT). The specimen. Results generally indicated linear stresses. GGOT, designed by the Turbine that the crack opening stress is a Technology Team, meets the require- function of the maximum stress. Sponsor: Earth-to-Orbit Technology ments of the STME lox turbine However, SWRI has found that dif- Office, Office of Advanced Concepts (fig. 131). ferent specimen geometries (center and Technology cracked panel, single-edge cracked plate in tension, and single-edge University Involvement: Southwest cracked plate in bending) exhibit Research Institute 1

FIOURE131 .--Major elements of the GGOT.

172 Technology Programs

TABLE8.--Exit volute design requirements performed by various team members of the volute alone, with methods of simulating the turbine/volute interac- AnnularDiffuser Volute Conicd Diffuser tion (such as by coupling the w)lute calculation with a one-dimensional Inlet MachNumber 0.84 0.79 0.66 turbine analysis), and of the entire turbine stage and volute. The results Exit MachNumber 0.79 0.66 0.30 from these studies will provide guid- ance to analysts about what methods Total PressureLoss 2.50_ 11.60% 3.40% must be employed to generate accu- rate volute predictions. Initial results from the entire turbine/volute model The baseline designs of the inlet and cause performance degradations and show a predicted increase in radial exit volutes have been completed. could produce increased turbine side pressure gradient over predictions Integration of the inlet volute design loads. Compounding the complexity from the stand-alone volute mode/ with the turbine stators reduced the of the volute design is the fact that by an order of magnitude. stator turning requirements, enabling rocket engine turbomachinery are an airfoil reduction count of approxi- generally operated at conditions off Results from these analyses will be mately 50 percent. CFD analyses of of their original design points. There- used to optimize the GGOT volutes. the inlet volute are currently in fore, the volute must be able to effi- In 1994, the designs and numerical progress, with the goals of minimiz- ciently function over a range of predictions will be verified with a ing the circumferential static pressure conditions. The baseline exhaust test of highly instrumented volute and gas angle gradients entering the manifold has been designed without models in the MSFC Turbine Airflow turbine. Delivering uniform flow guide vanes to reduce cost, weight, Facility. The volutes will be tested as conditions to the stator is the key to and complexity. Design requirements a system with the GGOT so that minimizing radial side loads on the for the exit volute system are shown proper boundary conditions will be turbopump shaft. in table 8. maintained. This program will further w)lute aerodynamic design technol- The aerodynamic design of the GGOT CFD analyses are currently being ogy, demonstrate the capabilities of exhaust manifold represents a formi- performed for the exit manifold. The CFD in the w_lute design process, dable challenge. This component most significant issue for the predic- and provide a unique set of volute must not only efficiently collect a tion of the exit volute performance experimental data. transonic turbine discharge flow, but is the application of the inlet bound- it must perform its function with ary condition. The exit volute and minimal interaction with the turbine the turbine are highly coupled. Sponsor: Office of Advanced stage. Undesirable interactions would Therefore, calculations are being Concepts and Technology

173 Research and Technology 1993

Development of The STME employs a gas generator experience of approximately 140 Advanced Turbine Blades cycle requiring the turbines to oper- degrees. CFD analyses of this design ate at very high values of stage- were performed by different team specific work. Traditional designs for members. The findings from each Lisa W. Griffin/ED32 the turbines would be velocity-com- 205-544-8972 analysis were incorporated into the pounded or pressure-compounded final GYr design, which was pre- impulse turbines. These types of In order to further the state of the art dicted to have significant perfor- turbines tend to be inefficient and of turbine aerodynamic design, the mance and cost benefits over have high Mach numbers. In order to Turbine Technology Team of the traditional designs (table 9). A par- meet the STME requirements and the consortium for Computational Fluid ticularly significant finding was the team's performance and robustness Dynamics Application in Propulsion effect of airfoil spacing on efficiency goals, the Turbine Technology Technology initiated an advanced and dynamic loading. Calculations Team's fuel turbine design---called performed for conventionally chosen subsonic turbine development pro- the Generic Gas Generator Turbine gram. The purpose of this program is axial spacing revealed an unsteady, (GVI')---incorporates reduced to demonstrate the benefits of CFD inner row shock wave (fig. 132). A through-flow velocities and increased application during the turbine design subsequent unsteady CFD study was reaction relative to previous gas process and to develop a turbine generator experience. performed to determine the optimal with increased efficiency and en- spacing. The G_F redesigned with hanced robustness. To ensure pro- this predicted optimal spacing gram output relevant to current Reducing the through-flow velocities showed a predicted gain of a point needs, the team focused on design required blading camber of approxi- in efficiency and a reduction in blade requirements consistent with the mately 160 degrees. This turning dynamic loading of 24 percent from STME. Concentrating on require- angle is well beyond the maximum the baseline design. ments for an actual turbopump al- lowed the team to focus on a clear TABtE9.--Comparison of conventional design and GST deliverable product and schedule. (as predicted by a meanline analysis) However, the resulting technology is generic. Conventional G3T

The Turbine Technology Team NumberofStages 2 2 consists of experts in turbine design, analysis, and testing representing w_ split 7o/3o s0/s0 the Government, industry, and BladeTurning 140degrees 160degrees academia. Each team member brings MaxBladeMathNumber 1.32 0.87 unique knowledge and expertise to the fuel and oxidizer turbines de- Efficiency Base + 9.8Percent signed for the advanced subsonic AirfoilCount Base - 55Percent turbine development program.

174 Technology Programs

LE

ID PreliminaryDesign

OD

g LE

ID finalBaselineI_sign

PredictedProlimiN_/Design FinalBaselineDesign FIGURE133.--Predicted streaklines downstream of the FtGURE132.--Temperature contours for the G3T For two axial spacings. GGOT rotor.

The team then incorporated the high the elimination of the separation. Griffin, L.W., and Huber, F.W. 1993. cambered airfoils into a design meet- The final design was predicted to Advancement of Turbine Aerody- ing the STME lox turbine require- have a gain in efficiency of two namic Design Techniques. ASME paper 9343T-370. ments. This design concept enabled points over the baselined STME lox a single-stage configuration, as op- turbine. The STME Program decided Huber, F.W.; Johnson, P.D., posed to the two-stage design to use the GGOT design concept for Montesdeoca, X.A.; Rowey, R.J.; baselined for STME. Analyses were its lox turbine, resulting in an esti- and Griffin, L.W. 1992. Design of again performed by various team mated life-cycle cost savings of Advanced Turbopump Drive members. Results from a 3--D Navier- $71 million. Verification of the de- Turbines for National Launch System Stokes analysis of the team's design, sign and the CFD analyses will be Application. AIAA paper 92-3221. called the Gas Generator Oxidizer provided by cold-flow testing of a Turbine, indicated a flow separation highly instrumented GGOT test ar- Sponsor: Office of Advanced downstream of the rotor at the hub ticle. The test will be performed in Concepts and Technology (fig. 133). The lean of the airfoil was the MSFC short-duration Turbine adjusted until calculations confirmed Airflow Facility in 1993.

175 Research and Technology 1993

Verification of Analytical influence on the subsequent behav- Fracture Control/Damage Methods--Single Cycle ior of that crack during single cycle Tolerance Methods for or multicycle proof testing. Versus Multicycle Proof Composite/ Anisotropic Testing A component that satisfies local Materials displacement control may be a poor candidate for proof testing of any Henry M. Lee/FD25 Rene Ortega/ED25 205 -544-7245 type because significant flaw growth 205-544-5448 can occur on any cycle. An im- The overall objective of this effort is proved analytical model based on Composite/anisotropic materials are to assess the relative advantages and tear fatigue has been shown to be increasingly being considered for disadvantages of single-cycle versus consistent with previous experimen- structural use in space systems. multicycle proof testing. tal and analytical observations. The These materials are capable of pro- new model shows great promise for viding many benefits to structural Rocketdyne, the current SSME unifying the framework to describe systems due to their strength capa- contractor, uses a multicycle proof multicycle proof test behavior. bilities, thermal properties, reduced testing procedure that consists of the Work to date has primarily been weight, and so forth. However, there application of five proof cycles at a focused on the high toughness, low is an increased need to accurately minimum pressure of 1.2 times the establish their damage tolerance hardening superalloy Inconel 718 TM. maximum operating pressure, each Other materials that exhibit low" capabilities. Damage tolerance is the with a minimum hold-time of 30 s. ability of a structure to sustain loads toughness characteristics, high hard- The proof pressure is selected to after crack initiation. Much research ening rates, or substantial cyclic keep nominal stresses below 85 per- on the damage tolerance of compos- softening will be studied. A practical cent of ultimate strength. A fracture ite/anisotropic materials has been engineering guidelines handbook mechanics-based theory of multi- carried out over the past 20 yr, How- will be developed that has a compre- cycle proof testing is being formu- ever, a need remains to compile and hensive formulations-of-proof test lated in terms of crack resistance consolidate the various aspects of philosophy for service life. curve concepts. Crack resistance the research that has been done in curves for surface crack panels of Sponsor: Office of Advanced this area.

Inconel 718 TM have been developed. Concepts and Technology Analytical and experimental work Damage tolerance consists mainly of previously accomplished has clearly Commercial Involvement: three aspects: (1) residual strength shown that the conditions of con- Rocketdyne, A Division of Rockwell provides the maximum damage the straint and control on the local level International structure can resist under fail-safe around a crack have very significant loads, (2) crack propagation defines the time period in which a crack grows from a defined detectable length to the allowable length deter- mined by the residual strength re- quirement, and (3) damage detection specifies inspection methods and intervals needed to identify flaws. The work reported here involves the residual strength and crack propaga- tion aspects of damage tolerance of composite/anisotropic materials.

176 Technology Programs

The objectives of this research are to Study of Trace platinum- and palladium-based develop a guidelines handbook for Contaminant Control catalysts for methane oxidation at damage tolerance testing of compos- high methane concentrations. The System Catalysts ite/anisotropic materials and to test activity is essentially the same as verified algorithms for calculating palladium-based catalysts currently flaw growth in these materials. These Jay L. Perry/ED62 in use for low methane concentra- 205-544-2730 algorithms are to be in a format that tions; however, the new catalyst can readily be inserted into existing exhibited significantly greater poi- computer codes. Development of a more robust soning resistance. In addition, under catalyst system for oxidizing atmos- humid conditions, the new catalyst A review of current state-of-the-art pheric trace contaminants at ambient showed higher activity than the testing methods for flaw growth and and moderately high temperatures palladium-based catalyst. fracture toughness was initiated on without poisoning is needed. Such a composite/anisotropic materials. system may eliminate the need for A performance prediction method Initial literature surveys were con- expendables, such as activated char- was also developed that assesses the ducted on damage tolerance inw)lv- coal, and high power requirements compatibility of the metal work func- ing single-crystal, laminated-metal, associated with regenerable charcoal. tion and metal oxide valence and and laminated-fiber composites. conduction bands for electron trans- Preliminary evaluation of the litera- The major objectives of this project fer and, therefore, allows a predic- ture on single-crystal materials re- are to screen suitable coprecipi- tion of which metal/metal-oxide rated catalyst candidates for metal/ vealed that stress intensity factors combinations make the most suitable and da/dN measurements are ap- metal-oxide catalyst development, catalysts. propriate parameters for estimating characterize activity and poisoning fracture growth. susceptibility, develop processing and fabrication techniques, and de- Sponsor: Office of Advanced The characterization of damage is velop a suitable catalyst support. Concepts and Technology, Small Business Innovation Research currently being explored for applica- A co-precipitated catalyst was devel- tion on current programs using com- oped that is capable of oxidizing posite materials, such as the SSME carbon monoxide at temperatures as C.ontmercial Involvement: TDA combustion chamber for laminated low as -70 °C with no water vapor Research, Inc. metals. poisoning. The catalyst also exhibits greater activity than conventional Engineering algorithms forcalculating fatigue crack growth life for compos- ite/anisotropic materials will be de- veloped. A wide range of crack type, geometry, and loading cases will be considered. Laboratory test data, when available, will be used to verify the accuracy of the developed algorithms.

Sponsor: Office of Aeronautics, Exploration, and Technology

177 Research and Technology 1993

Dynamic Modeling Porous Wall Flow or generated from, porous walls of Bearings Experimental Facilities have been developed. The facilities include a flow resistance chamber, a shear flow water tunnel, and a duct Stephen G. Ryan/ED14 Andrew W. Smith/ED36 flow air chamber. 205-544-1467 205-544-4932

Rolling element bearing models The simulation of the internal flow The purpose of the flow resistance chamber is to obtain the mass flow typically ignore race flexibility and field of SRM's in cold-flow tests re- clearance (deadband) in the bearing quires the prescription of a uniform and pressure loss relationship for a support. Enhanced mathematical blowing velocity injected through the porous wall sample. This curve is models and associated computer wall. This blowing from the model important in the design of an SRM programs have been developed wall simulates propellant burning cold-flow model for determining air that include the effects of race and within the rocket motor. The uniform supply requirements. The chamber support flexibility and outer race blowing velocity distribution is usu- can test samples up to 10 cm in diameter at a maximum flow rate of deadband on the force deflection ally simulated using porous wall relationships (stiffness) of ball and tubes that are pressurized to yield 0.45 kg/s. Recent testing in this facil- roller bearings. different blowing rates. Knowledge ity has focused on the reliability of of the flow behavior from porous pressure-drop information from the This analysis tool, known as Flexibility materials is important for under- material supplier, and the discovery Enhanced Rolling Element Bearing standing the wall's contribution to that upstream side surface conditions can influence the flow resistance of Analysis (FEREBA), utilizes ANSYS TM the internal flow field. finite element models of the races, the material. support structure, and the deadband Recognizing the need to support the (gap elements) to represent the MSFC cold flow Solid Rocket Motor The shear flow water tunnel(fig. 134) flexibilities of these elements. These Modeling Facility, laboratory-scale was developed to investigate the data are integrated into a classical experimental facilities for investigat- near wall flow behavior of porous quasi-static analysis formulation ing internal flows contributed by, wall flow (y direction) in the where general motion of all elements is allowed. Preload springs can be ]w included in both simplex and duplex arrangements. This tool enables more accurate prediction of bearing mechanical behavior for use in rotor dynamic analyses.

Sponsor - Earth-to-Orbit Technology Office, Office of Advanced Concepts and Technology

PorousWallArea--% 6.0in× 4.0in _E_ DivergenceAngle

Qw+Q__ Te_/RowVizSer_n _ Q_

FIGURE134.--Shear flow water tunnel.

178 Technology Programs

presence of a shear flow (x direction). dominated flow over a length of Smith). This experience has been A combined flow rate of 17.6 L/s is 610 cm. This rig is capable of a combined with the test rigs de- possible. The two flow-conditioned Reynolds number (based on duct scribed in this article to provide legs meet in an acrylic test section, half height) of 2 × 10E5 that affords the technical expertise required for providing optical access for Laser the study of flow transition from understanding the internal fluid Doppler Velocimetry (LDV) and flow laminar to turbulent flow. The pre- dynamics of an SRM. visualization of the interaction re- dicted theoretical axial velocity gion. Recent studies with various (Culick's profile) was confirmed by McDaniels, D. July 1993. Posttest Report material porosities showed the de- LDV measurements. Initial results of Test STMOO08 (Porous Material Pressure Drop Characterization). pendence of near-wall flow behavior have also shown the dependence of NASA Memorandum ED3/+-20. on the pore diameter Reynolds num- flow not only on the axial and injec- ber and revealed recirculation re- tion Reynolds numbers, but also on Ramachandran, N., Heaman, J., and gions very near the wall for the porous material characteristics Smith, A. 1992. An Experimental nonuniform pore-sized materials. (fig. 135). Study of the Fluid Mechanics Associ- ated with Porous Walls. Presented at The duct flow air chamber (fig. 135) In addition to the development of the 30th AIAA Aerospace Sciences consists of two porous walls (top these rigs, other bench tests have Meeting, Reno, N%,'. and bottom of the duct) with acrylic been conducted. Velocity field sur- Yeh, Y.P. Quarterly Progress Report 4. side walls. The duct height is vari- veys of pressurized porous cylinders Cold Flow Studies in Support c)f the without axial flow led to the discov- able, with a maximum separation of ASRM Program. NAS8-38679. 50 cm. One of the ducts is blocked, ery of a critical velocity that can be allowing the duct flow to shift from used to predict jetting behavior Sponsor: Solid Propulsion Integrity (Ramachandran, Heaman, and wall injection flow to axial shear Program

Flow Pressure University Involvement: Universi- MeierGauge ties Space Research Association

Commercial Involvement: Engi- neering Research Corporation Regulator ! ( ConlrolValve

I flowMeier

---'C) PressureGauge I : ---C) Thermocoul_e i Orifice

PressureGmsge

I ReliefVolve Max.20-25psig J I Atmospheric RowExit

FIGURE135.--Duct flow air chamber.

179 Research and Technology 1993

Verification of Analytical Methods: NASA Crack Analysis Code

Roderick Stallworth/ED25 205-544-7189

The NASA Crack Analysis Code (NASCRAC) is a state-of-the-art frac- ture mechanics analysis computer code. This research effort involves the verification and validation of the code and determination of the limits of applications, with the end result being the capability for more effi- cient fracture analysis. In the area of crack transitioning, the NASCRAC results were compared versus experi- FIGURE136.--Fracture specimen with prefatigue notch. mental testing. Figure 136 shows the fracture specimen with the prefatigue Analytical verification consists of notch Figure 137 shows NASCRAC- In_idN01cfl 15,000Cydes comparing NASCRAC code results predicted results and the results with literature sources and finite observed from testing. NASCRAC element model solutions. In the case predicted that the crack would grow of a surface crack in a solid cylinder, faster than was observed. Therefore, in this case NASCRAC proved to be NASCRAC predicts a constant stress conservative. For this case, the semi- intensity (K) value across the crack front where 3-D finite element anal- elliptical surface flaw in a plate, 30,000Cycles 45,000Cycles NASCRAC predicted that the flaw ysis showed the K values changing would transition to a comer crack at from the edge to the apex of the flaw. 26,000 cycles, compared to observed experimental data that showed the Comparisons and results previously crack growing to a comer flaw at summarized help to quantify the 35,000 cycles. NASCRAC predicted limits of accuracy and application of 60,000Cyc 7S,O00Cyd transition from a corner flaw to a the NASCRAC code. Verification and through flaw, and then failure at validation of the code is ongoing, 73,000 cycles. Experimental results with the end result being improved showed transitioning to a through life prediction analysis capability. crack at 138,000 cycles without failure occurring. Sponsor: Office of Aeronautics and Civil Technology J_ O_dIIASCI_Cj

FIGURE137.-- NASCRAC-predicted results and results observed from testing.

180 Technology Programs

Grid Optimization Tools grid for a specific problem. A more time-stepping, until an equilibrium for Complex Models efficient approach would be to gen- of spring forces has been estab- erate a generic grid and then to opti- lished. The variational moving node mize it for a specific problem. The method optimizes the physical grid Grego_ R. Swanson/ED25 cost of preprocessing can be reduced relative to a set of reference ele- 205-544-7191 through the development of soft- ments. An advancing front method is John M. Price/ED27 ware tools that allow the rapid modi- used for local remeshing. The user 205-544-4645 fication and conditioning of finite selects a region of the existing grid element grids. to be refined or coarsened. Today, cost plays a decisive role in the design of aerospace structures. Phase I has been successfully com- Under an SBIR Phase I contract, pleted. The results, presented in a New computational tools are avail- Alabama Research, Inc., of Hunts- able, but are not being used rou- final report, indicate that the mesh ville, AL, is developing a grid opti- tinely because of implementation optimization strategy has been dem- mization tool for complex structural costs. Probabi]istic methods, large- onstrated as a practical tool for models. The principle investiga- scale design optimization of aero- reducing the cost of analysis. tors are Mr. Lawrence Spradley, space vehicle structures, structural Dr. Rainald Lohner, and Mr. Jean sensitivity, and inverse design prob- Cabello, J.; Lohner, R.: and Jacquotte. O.P. Cabello. The objectives of this Phase I June 3-4_, 1991. A Variational lems require repeated analysis. The SBIR are to: (1) establish a practical Method for the Optimization of practical implementation of these strategy for improving grid quality, Directionally Stretched Elements computational technologies depends (2) show that optimization tech- Generated by the Advancing Front on how much a single analysis costs. niques can be used to improve Method (AFM). The 3d International The goal is to seek the most cost- Conference on Numerical Grid the quality of finite element grids, effective analysis. Generation in CFD and Related (3) verify that this grid optimization Fields, Barcelona, Spain. An analysis can be divided into strategy can be used with existing preprocessing, solution, and post- finite element models, and (4) dem- Lohner, R., and Parikh, P. 1989. Three- processing tasks. In the past, much onstrate that this strategy can be Dimensional Grid Generation by the attention has been directed toward used to reduce the cost (time and Advancing Front Method. Interna- money) of analysis. tio_al.lou mzal of Numerical Methods reducing the time required to obtain in Fluids 8:113_-49. a solution. Today, most of the analy- sis time is spent in preprocessing A practical strategy for grid optimiza- Spradley, L.W.: Lohner, R.: and Cabello, J. and postprocessing activities. One of tion has been demonstrated that 1993. Grid Optimization Tools for the most costly and time-consuming combines moving node methods, Complex Structural Models. NASA AR-93-01. preprocessing tasks is the construc- local remeshing, a simple user inter- tion of the finite element model face, and interfaces with an existing Sponsor: Office of Advanced Con- representing the physical problem commercial finite element code cepts and Technology, Small Busi- Grid quality directly affects the qual- (ANSYS44a). Spring and variational ness Innovation Research Program ity of the solution, but grid quality moving node methods are imple- depends strongly upon the specific mented. Both methods adjust exist- Commercial Involvement: problem to be solved. Hence, a good ing interior grid points. The spring Alabama Research, Inc. grid for a specific load case becomes method treats each side of an ele- a poor grid for another load case. ment as a spring. These springs Current practice is to generate a are relaxed in time, using explicit

181 Research and Technology 1993

Combustion Chamber schemes, and noniterative pressure- - Four differencing schemes: Analysis Code implicit split operator (PISO) solution upwind (first/second order), procedure. Fundamental develop- central (with damping terms), ment, testing, and validation efforts monotonic upstream schemes P. Kevin Tucker/ED32 were directed to the development of for conservation laws 205-544-4185 robust numerical techniques, as well (MUSCL), and third-order as physical models. Parallel to the Osher-Chakravarthy The overall objective of this project code development, continuous sup- was to develop a 3-D computational - Fully implicit and conservative port was provided for analyzing formulation fluid dynamics code that could be flows and heat transfer problems used as an analysis tool in designing during the STME development effort; - Stationary and rotating coordi- liquid propellant rocket engine thrust e.g., National Launch System mani- nate systems chambers. Until recently, thrust fold study, STME nozzle cooling, - Symmetric whole field linear chambers were designed using vehicle base heating, and so forth. method of characteristics (MOC) equation solvers and conju- techniques and boundary layer ap- The main features of the REFLEQS gate gradient solvers. proximations. In the last two dec- code are: ades, new prediction methodologies Physical Models • Numerical Techniques based on solutions of Navier-Stokes - Advanced turbulence models equations have evolved. Thus, CFD - Finite-volume approach of with boundary layer treatment has become one of the viable tools solving Favre-averaged (with standard/extended wall for the design of rocket engines. (steady state/transien0 Navier- functions): (a) Standard k-e Stokes equations for com- Model, (b) Extended k-e Three major activities of this project pressible/incompressible flows Model, (c) Multiple Time Scale included: (1) development of a new - Cartesian, polar, and non- Model, and (d) Low-Reynolds generation REFLEQS CFD code with orthogonal body-fitted coordi- Number k-e Model colocated (nonstaggered) formula- nates (BFC) tion, (2) code verification and valida- Instantaneous reaction (diffu- tion against high-fidelity benchmark - Colocated (nonstaggered) grid sion-controlled combustion) model data, and (3) computational studies arrangement supporting STME engine develop- - Pressure-based methodologies Equilibrium chemistry model ment. A state-of-the-art numerical such as semi-implicit method (based on element potentials methodology was developed by for pressure linked equations method) implementing nonstaggered grid (SIMPLEC) and noniterative arrangement, strong forms of the One-step finite rate chemistry PISO algorithms for all flow conservation equations expressed in models and two-step reduced speeds terms of Cartesian velocity compo- mechanism models for nents, higher-order total variation - Blockage technique for flows Oe/H 2 and Oz/hydrocarbon diminishing (TVD)-type numerical with internal solid objects propellants

182 Technology Programs

High-Accuracy CFD Methodology for Fast Flow Transients and Nonlinear Instability Phenomena

P. Kevin Tucker/ED32 205-544-4185

Analysis of nonlinear combustion instabili W problems requires the use of nonoscillatory, high-accuracy nu- merical algorithms. Development of numerical methods for the treat- ment of high-speed flows has re- ceived much attention during the last 10 yr. Methods are now available FIGURE138.--Temperature FIGURE139.--Mach number that are capable of simulating com- distribution in the distribution in the pressible flows in two and three computational domain. computational domain. dimensions in complex geometries. A comprehensive assessment study Eulerian/Lagrangian, two- Results obtained from REFLEQS for was performed under a Phase I SBIR liquid evaporating reactive the modeling of the flow in the base project in which all advanced shock- spray dynamics model with region of the space vehicle and capturing CFD techniques were turbulent disperson effects STME nozzle are given in tempera- implemented and tested for one- ture and Mach number distributions, dimensional test problems, such as Turbulence-combustion inter- respectively (figs. 138 and 139). shock tube and resonant tube simula- action models using the prob- tions. In the follow-up SBIR Phase II abili W density function (pdf) $1_nsot: Office of Advanced project, a modular CFD code Fast method Concepts and Technology Transient Analyses (FASTRAN) was developed for 2-D and 3--D flows, - Discrete ordinate thermal Commercial Involvement: CFD The algorithms used in the code are radiation model. Research Corporation of second-order accuracy in time and at least second-order accuracy in space, and include the flux-corrected transport (FCT), TVD, essentially nonoscillatory (ENO), and Godunov approaches.

183 I Research and Technology 1993

A General Computational Fluid Dynamics Code for All Mach Numbers

Ten See Wang/ED32 205-544-0503

An extension of the preconditioning techniques of Van Leer and Roe to 3-D inviscid flow with generalized chemistry has been developed and FIGURE140.--Computed density contours for a Mach 1.3 shock wave. implemented in the CFD code Gen- eral Aerodynamic Simulation Pro- {a)Densitycontoursatlater stages. (b)Pressurehistoryona cylinderwall gram {GASP). As a result, GASP is 4O now capable of efficiently solving problems over the entire Mach num- ber domain. A plot is presented for flow over a circular arc" airfoil that .o.20 demonstrates the savings achieved with preconditioning over a Math to number range of 0,1

An M=0.001 flow was chosen to FIGURE141 .--Wave propagation in an annular cylinder. demonstrate the capability to predict incompressible flowfields through Results of simulations that have been Existence of such pressure waves the use of preconditioning (fig. 143). performed using FASTRAN for pur- can have an adverse effect on perfor- Not only does GASP with precondi- poses of algorithm comparison show mance of liquid rocket engines; and, tioning accurately predict the results the comparison of experimental therefore, it is essential that a nu- (when compared to potential func- shadowgraphs with computed den- merical simulation can correctly tion results), it is able to converge sity contours for shock diffraction account for their formation and the problem with the same efficiency over a 55-degree wedge {fig. 140), behavior. and the nonlinear resonant acoustics as the compressible flow problems. within a chamber cross section in the Sponsor. Office of Advanced Con- To put this in perspective, without form of multiple wave reflections cepts and Technology, Small Busi- adding preconditioning techniques a density-based code is not capable of induced by an initially plane pres- ness Innovation Research Program sure wave (fig. 141). The scattering accurately or efficiently solving in- Commercial. Involvement- CFD of a plane wave by the curved walls compressible flow problems. The use prevents formation of shocks and Research Corporation of preconditioning makes it possible leads to formation of large ampli- tude, undissipative pressure waves.

184 Technology Programs

100 to efficiently solve incompressible flow calculations without making assumptions that would prevent the flow" solver from accurately predict- 8O ing compressible flowfields.

In addition to providing incompress- ible capabilities, preconditioning has 6o the added benefit of significantly improving the convergence rate for problems at all Mach numbers.

• . 40 Sponsor: Office of Advanced Con- cepts and Technology, Small Busi- ness Innovation Research

Commercial Involvement: 20 Aerosoft, Inc.

I I 0o 0.2 0.4 0.6 0.8 1.0 MachNumber

FIGURE142.--CPU savings due to preconditioning for flow over a circular arc airfoil.

Level Cp 0 0.245 C 0.206 B 0.168 A 0.130 9 0,092 8 0.054 7 0.016 6 -0.022 S,-- 5 -0.060 4 -0.098 3 -0.136 2 -0.174 1 -0.213 -2 -I 0 I 2

FIOuRE143.--Pressure contours for Moo=O.001 flow over o circular arc airfoil.

185 Research and Technology 1993

Fast Algorithm models incorporated. Very efficient Hubble Space Telescope Combustion Modeling solution algorithms have been identi- Pointing Controller fied for steady state and transient Redesign flow applications. Models for the Ten See Wang/ED32 droplet breakup, evaporation, and 205 -544-0503 combustion have also been imple- Mark S. Whorton/ED12 205-544-1435 mented and tested using the same Numerical accuracy and computa- CFD model. tional efficiency of a time-accurate, Control system design for flexible pressure-based computational fluid The results of benchmark evaluation space structures (large space struc- dynamics (CFD) methodology, with cases have shown good comparisons tures (LSS)) is a challenging task that physical models describing the finite- between the computational predic- motivates today's intense research in rate chemistry and spray evaporation tions and the measured data for modem robust control theory. The and combustion, have been evalu- evaporating spray. Further develop- performance objectives of many ated. An operator-splitting predictor, ment and testing work for the dense spacecraft are quite ambitious, as is plus multiple correctors viscous flow spray physical models using the the case with the Hubble Space Tele- solution method with 3-D multizone method of volume of fluid, which scope (HST), launched in April 1990. capability, has been employed for has been planned for future study, The HST is the most complex and solving finite-rate chemistry and will complete most of the require- advanced space observatory ever spray combustion-related problems. ment to make the present CFD built. More than 1,900 observations combustion model to be a user- of nearly 900 astronomical objects Two approaches to solving a finite- friendly, robust, accurate, and effi- were carried out in the first 18 mo of rate chemistry system of equations, cient engineering tool for the design operation. To achieve the science including a point implicit integration and analysis of rocket engine objectives, alignments of HST optical method and a penalty function combustion-related problems. components must be maintained to method, have been incorporated within 1/400 mm and pointing stabil- and evaluated for various types of Sponsor: Office of Advanced Con- ity must be maintained to within reacting flow problems (fig. 144). cepts and Technology, Small Busi- 0.007 arc seconds radian means Steady state and transient test cases ness Innovation Research Program per second (RMS) (or an angle less with premixed and/or diffusion Commercial Involvement: than the width of a dime seen from flame flow conditions have been Engineering Science, Inc. 300 km away). investigated to validate the accuracy and robustness of the physical After initial deployment, the HST experienced severe pointing distur- bances due to thermal excitation of

...... _._.._T- _ i _ i _ . . . the solar arrays. Since this problem ...... i was first recognized, several control system redesigns have been carried out by the pointing control system team at MSFC and Lockheed Missiles ..... :.:. : : : . . : : : : . . : : : : : : : , : and Space Company. These rede- signed controllers have been up- GasFlow Field linked to the spacecraft with increasing degrees of success.

Since this challenging controller design problem was representative of control/structure interaction (CSI) issues, an HST Pointing System Performance Enhancement Study was conducted. The results of this Poly-disperse,SMR=5.O _n study were presented along with a FIGURE144.--Solid-cone spray simulation at P= 1.1 MPa and t=4.5 ms. 186 Technology Programs

tutorial paper in a session spon- Quantifying Spacecraft Augmented Orbital sored by MSFC at the 16th Annual Crew Safety From Orbital Debris Shield Concepts American Astronautical Society Guid- Debris Penetration ance and Control Conference held for Space Station Critical Elements February 6-10, 1993, in Keystone, CO. The purpose of this study was JoelE. Williamsen/ED52 205-544-7007 to apply advanced modern control JoelE. Williamsen/ED52 methodologies that have been devel- PedroI. Rodriguez/ED52 205-544-7007 205-544-7006 oped under the MSFC CSI program PedroI. Rodriguez/ED52 funding to a challenging "real world" 205-544-7006 problem. Five principal investigators The penetration by meteoroids or from four universities and one con- orbital debris of small module vol- With the recent increase in the tractor were provided with detailed umes occupied by crew members in orbital debris population, spacecraft models, simulations, and flight data space, has often been associated in in low-Earth orbit require advanced from the HST and asked to apply the past with immediate crew loss. shield concepts employing maximum their control methodology to the However, with the advent of large, overall protection-to-weight ratios. pointing control system to explore multichambered spacecraft designs, Toward this goal, a team of MSFC possible performance enhancements. crew loss need not necessarily follow and JSC engineers designed and The solar panel thermal snap distur- spacecraft penetration by orbital tested a family of weight-efficient bances were to be minimized or debris particles. A computer simula- orbital debris shield concepts that eliminated in the resulting closed- tion tool, MSCSurv TM, can be used to could augment existing space station loop system design. identify interior spacecraft designs, shields either on orbit or prior to crew work and sleep schedules, and launch (fig. 145). The tutorial was an overwhelming other factors that affect crew safety success. The editor of the AIAA following the remote possibility of Shield concepts generally employed Journal of Guidance, Control, and spacecraft penetration by orbital advanced materials (such as NexteF M Dynamics has requested that a spe- debris. AF52 and Kevlar TM 49 cloth) com- cial issue of the journal be compiled bined in layers to maximize protec- highlighting the study and its results. This program quantifies the hazards tion capability. This study also The continued development of mod- of decompression, injury, and space- minimized shield support structure ern control theory, coupled with craft structural failure, given the weight within the framework of input parameters of spacecraft geom- practical applications to challenging minimizing total shield system CSI problems, is an essential element etry and shielding, crew location, weight. Astronaut extravehicular in preparing the control community strike location, and crew protection activity (EVA) compatibility with to design systems for the more ambi- afforded by internal equipment. The orbitally augmented shields was tious spacecraft that are envisioned hazard analysis and quantitative verified through neutral buoyancy for future development. output from this safety study should testing. be valuable to crewed spacecraft Sharkey, J.; Nurre, G.; Beals, G.; and designers. Shield concepts resulting from this Nelson, J. August 1992. A Chronol- study are broadly applicable to other ogy of the On-Orhit Pointing Control Sponsor: Space Station Program government or industry spacecraft System Changes on the Hubb]e Office Space Telescope and Associated designs. Pointing Improvements. AIAA paper 92-4618 Sponsor: Space Station Program Office Sponsor: Office of Advanced Concepts and Technology

Comanercial Involvement: Lockheed Missiles and Space Company

187 Research and Technology 1993

Modified Baseline Confonnal,AugmentedBaseline

Optioe1 Option2 Opthm3 Option4 (=1 CMProtectionLevel) (=10A Protectionlevel) (_1.5 C.MProtectionLevel) (=20d ProtectionLevel}

-- .OSin 6061-16 -- .OSin6061-16 -- .05in 6061-16 -- .OSin 6061-T6 J 2.25in 8-instandaff 4in 4in AIMesh _vvvvvvvvvv Nextel ...... Nextel _:,_p;_:_ NexlelAF62 4 in 4in Kevlar7i0 ^^^^^^_^^^_ /4LI v_wwvvvvv Nexlel ...... Nexlel 50mill] _ i 2.25in MLI 125/4LI so,/J , _ .! 252219-T87 MU ._ ...... /411 = r !25 rail "_

AdditionalshieldwL0.458g/cm7 Addilionalshieldwl.O.345g/cm2 Additionalshieldwl.0.665g/cm2 Additionalshieldwt.1.445g/cm2 _14.31b/shield --34.5Ib/shield _56.5Ib/shield

SeeOptbn2 CrossSection

__//42.4 in

SeeOptions3 and4 CrossSe(tions

2.4in • _ 53.2in _*/

FIGURE145._Habitable module shield concept summary.

188 Technology Programs Systems Analysis and Integration II | I II

Autonomous Signal Analysis and Reconfigurable Modeling System

Navigation and i Attitude Filter ., James W. Parker/EL56 205-544-2340

James J. Lomas/EL58 205-544-8305 The objectives of this effort are to z design, develop, validate, demon- strate, document, and deliver a signal The integrated Global Positioning analysis and modeling system (SAMS) System/Conical Earth Sensor/Sun LEO GFS GD data base methodology and modeling Sensor (GPS/CES/SS) system being Orbital Altitude tool for detailed modeling, simula- developed under the SBIR Phase II tion, analysis, technical manage- Program supports the NASA space- ment, and archival of spacecraft and/ craft autonomy goals. This research GEO-GeosynchronousLEO-Low-EorthOrbilEarthOrbilI or experiment signal requirements addresses the spacecraft autonomy issue from two technical directions: and characteristics. This tool is ca- FIGURE] 46.-- Performance crossover pable of accommodating a minimum (1) selection and integration of navi- characteristics. of 10,000 signals per program, which gation and attitude sensors that are include both hardware and software applicable to a wide variety of mis- measurements and commands that sions, and (2) incorporation of transition from one sensor operation comprise the instrumentation pro- real-time software reconfiguration to the other, depending on the mis- gram and command list (IPCL). SAMS technology to address mission sion timeline, geomet W, and sensor consists of three models: (1) the data contingencies. health and status. base development model. (2) the The complementary performance This research will demonstrate the data base analysis model, and (3) the simulation model. features of the GPS and CES/SS will innovative sensor integration and provide continuous, accurate 3-D software reconfiguration concepts navigation and attitude estimates through proof-of-concept demonstra- Many large systems, such as the irrespective of the location of the tion hardware. The demonstration space station, contain increasing spacecraft with respect to the Earth, hardware will be a hardware-in-the- numbers of complex systems and Sun, and Moon. Another important loop simulator that will be used to science instruments that demand an mission benefit of integrating GPS validate the perfomlance benefits of enormous increase in the number of with CES/SS (via the real-time recon- the integrated, autonomous, recon- signals. The signal requirements are figurable software) is the resulting figurable GPS/CES/SS system. driven by an)bitious national and improvement in functional redun- international science demands, the dancy (fig. 146). The reason for this inclusion of a crew on board, the Sponsor: Office of Advanced benefit is that the physical phenom- increased emphasis on safety, and Concepts and Technology, Small ena that limit the performance of one Business Innovation Research high-tech, computer-driven flight sensor do not affect the other sensor hardware. A major responsibility of Program and that the failure of one sensor systems engineering is to manage still permits the mission to continue, and account for a signal complement albeit at a degraded level. The use Commercial Involvement: May- expected to exceed 10,000 measure- of reconfiguration software technol- flower Communications Company, ments and commands (scientific, Inc. ogy, in the proposed integration operations, test, and housekeeping approach, "fuses" the solution from data and commands)over a duration the two sensors and allows a smooth of 10 yr or more. The complement ()f

189 Research and Technology 1993

signals will change at regular inter- capable of including and accounting The software is being developed by vals as additional facilities are at- for every signal used to test, verify, Stanford Telecommunications, Inc., tached during the buildup and as and operate a system. in Seabrook, MD, under contract to experiments are changed out or MSFC, and is hosted on a UNIX- The data base analysis model consists augmented. The large number of based Digital Equipment 5000 work- of three integrated subtier models. station. The software builds are signals that must be analyzed and The first is a data archival model that tracked cannot be efficiently handled nearly complete. Planned work re- provides for requirements traceability by manual sorting and comparison maining includes completing the and defines the computer memory of signal lists. Currently, no com- data base architecture and software documentation of the design of the puter-automated tool exists that pro- software code, the users guide, and a hierarchy associated with the ma- vides a specialized procedure of step-by-step software configuration nipulation, archival, and output of guide. In addition, the software func- analyzing and managing complex multiple IPCL data bases. The second signal lists, is a data correlation model that per- tions will be validated and any bugs discovered during the validation will forms the setup, selection, process- be corrected. The SAMS is a computerized systems ing, generation, and storage of data engineering tool designed to archive for reports that compare IPCL data and manage IPCL data bases, pro- bases representing the configuration SAMS is currently in use and contains vide traceability of requirements of a system at different stages of the space station signal data base. and design changes throughout the development, and reports the select- The software/hardware system program life, and develop selected able differences in the data-base for- validation will be performed as this subsets and data reports in support mat. The third is the performance program data base is manipulated. of trade studies, changes, growth, analysis model that provides the cap- and evolution. The tool provides ability to statistically analyze the per- The SAMS provides a computerized increased efficiency in monitoring formance and validate the technical methodology for storing, sorting, and and assessing data management composition needed to support trend analyzing the signal requirements systems requirements, verifying and analysis and to ensure adequate and characteristics. The tool greatly making visible adequate systems margins in data-handling resources. improves the efficiency of a systems resources such as signal bandwidth, The simulation model is called the engineer to perform analyses and memory, CPU throughput and mar- data systems dynamic simulator trades, and to assess and ensure gins, and other architectural compat- (DSDS) and allows the development compatibility of data management ibility with mission data models. The of a data management system model system resources with data flow generalized functional requirements that simulates the functions of the requirements. allocated for SAMS are as outlined system on an events/timeline basis to below. provide statistical performance analy- Sponsor: Office of Space Systems sis and trades. These analyses and Development The data base development model trades yield a prediction of the per- Commercial Involvement: Stanford provides a standard signal data base formance of the system and identify architecture and the tools needed to incompatibilities early in the design Telecommunications, Inc. load, monitor, manage, and access so that problems can be corrected at this data base. This architecture is a minimum of cost.

190 Technology Programs

Thermospheric Density MET model provided. This was frequency and duration of neutral Variations Simulator because: (1) the basic design was density deviations greater than the significantly different than previous design-to-values, for use in designing satellites, and (2) the microgravity and testing the guidance, control, B. Jeffrey Anderson/EL54 experiment requirements were more and navigation (GN&C) systems 205-544-1661 stringent. A simulator--a computer required to conduct microgravity code that would generate realistic experiments; and (3) a computer For most engineering applications, data emulating density variations-- simulator to be used with the MET NASA has adopted the Marshall Engi- was also required so the systems model that would produce perturba- neering Thermosphere model to could be analytically exercised to tions in neutral density with periods define the total mass density at or- ensure that they would meet the from a few minutes to 3 h, for opti- bital altitudes. Total mass density requirements. mizing and verifying GN&C system determines the drag on the vehicle, software. thus the MET model ix most often This problem was complicated by thought of in terms of orbital lifetime The historical solar activity indices the fact that the MET model is based calculations. However, drag on the were used to generate values of the on proxy input parameters that are vehicle also can cause torques and minimum, mean, and maxinmm imperfect representations of the affect the microgravity environment, exospheric temperatures on the parameters that actually control the so the model is also used to analyze globe (which the MET model relates thermosphere, and predictions of control system designs and space- to density) for eve W 3-h period from these proxy inputs are unavailable based experiment microgravity 1947 through 1991. These tempera- for future time periods, when the levels--applications where rapid tures were indexed to five different space station will be in orbit. The variations in the environment are levels of solar activity--as defined by only predictions currently possible important. The shortest time scale the 13-too smoothed 10.7 cm solar are for the 13-mo smoothed values variations within the MET model are radio noise flux values--and cumu- of the input parameters and, until those occurring every 3 h as a result lative percent frequency (CPF) distri- this effort, no research had addressed of the geomagnetic storm index (ap) butions were computed for each of how they should be used to produce variations. The only neutral density the five different levels of solar activ- design-to-density values that would variations at orbital altitudes with ity (Smith et al. 1991). These CPF's ensure reasonable risk levels without time periods less than the orbital can be used to select the proper risk an over-design. period are those associated with levels in design trade studies. internal gravity waves; however, The aim of this activity was to de- These same CPF's were used to: these had not been modeled until velop: (1) statistics of the distribu- (1) determine how frequently speci- this study. tions of "actual" values of neutral fied density levels were likely to be densities about MET model-estimated exceeded and their duration, and As the design of the space station values (derived from using 13-too (2) establish files of input parameters experiment complement ew)lved, it smoothed input parameters) so that that would generate 90-d density became evident that design engi- program managers could determine profiles R)r use in design and tests neers needed more information risk levels associated with specific of both control systems and opera- about density variations with time design-to-density values; (2) statistics tions methods, to determine if mis- periods on the order of a few min- of the perturbations with periods of sion requirements can be attained utes to a few hours, shorter than the 3 h or longer to determine both the (tlickey and Smith 1992).

191 Research and Technology 1993

I00 b (q_= 0.853,ao2= 4.02x10-4) m LowOp I

Period (s)

I00

im ((p= 0.832,aa2= 3.68x10-4) m Highop I

lO-I

0 L Data

10-2

10-3 I I I I I Illl I I _ ' ,,,ll i I i i i i ii 101 10 2 103 104 Period(s)

FIGURE147.--First-orderautoregression fit to average power spectral densities for low solar activity.

192 Technology Programs

A definition and simulation method densities were derived by averaging (3) inclinations <30 degrees, (4) re- for the small-scale, within orbit, over at least one hundred such spec- stilts show little dependence on ap. variations due to internal gravity tra for each of the four ap--F,_ bins. Additional work is needed to extend waves was still needed. This led to The length of each individual data the simulation to high-inclination the development of a wave model string from which these spectra orbits. that can be used in conjunction with were derived corresponds to about tlickey, M.P. September 1993. Simul:tticm the MET model (Hickey 1993). Data 15,000 km along the satellite track. of Small Scale Thermospheric Den- from the Neutral Atmosphere Com- sity Variations for Engineering Appli- position Experiment mass spectro- First and second order autoregression cations. PI tY-93R044. meter on the Atmosphere Explorer-E models were fit to the average satellite, flown fr()m December 1976 power spectra density curves by Hickey, M.P., and Smith, R.E. 1992. to April 1981, was binned according utilizing and modifying the Maxi- Ninety-Day Solar and Geomagnetic Activity. Input filed for Thermo- mum Entropy Method equations, to tile 3 hourly ap and the 13-too spheric Variation Simulation: from which the "best-fit" autore- smoothed lO.7-cm flux (F_._) values. Sinltll:lli(m Data Files,, Release 2. Four bins were produced, two for gression parameters were derived Ptt Y-92R 103. each of the ap and F_ values. After (fig. 147). The result is a subroutine filtering the combined atomic oxygen that can be used with the MET Smith, R.E.: Ariderson. B0.; and ('atleit, K. and molecular nitrogen (the major model to provide realistic simulation 1991. The Marshall +l+hcmlosl+herc Mode/ Atlnosphcre: Statistical constituents in the middle to tipper of the minute-to-nlinute density Analysis Mode ( MET-SAM ). AIAA thermosphere) density values, and variations a satellite will experience 91q)._53. then analyzing the spectral content in love-Earth orbit. Model restric- using the Fast Fourier Transform tions/limitations are: (1) F _ iriust be Sponsor: Space Station Program technique, average power spectral <210, (2) orbital ahitude 250-500 kin, Office

193

MSFC Technology Within these areas are numerous technology transfer, the result is a Transfer Opportunities activities that are applicable to a major cost savings to industry. An and Successes wide range of the commercial sector. excellent example of a technology Industrial partners may transfer transfer "enabler" mechanism is the technology already developed by Productivity Enhancement Complex Technology transfer is recognized as NASA toward new product develop- operated by the Materials and Pro- a vital aspect of every MSFC organi- ment or process enhancement, or cesses Laboratory at MSFC. Here, zation. Businesses are encouraged to can team with MSFC in research to NASA and industry work together to team with project offices, laborato- address an industry-identified need. develop new materials, processes, ries in the Science and Engineering Whatever the chosen method of and assembly techniques. Directorate, and offices in Program Development to adapt technologies for commercial use.

The major research and technology thrusts at MSFC include:

• Propulsion systems • Structures and dynamics • Materials and manufacturing processes • Avionics and optical systems • Automation and robotics

• Astronomy and astrophysics • Earth science and applications • Solar terrestrial physics • Microgravity sciences.

196 Technology Utilization National Technology Transfer Program Center (NTTC) and Regional Technology Transfer Centers (RTFC) which conduct technol- The MSFC Technology Utilization ogy searches and offer many (TU) Office accepts problem state- other technology planning ments and technical inquiries from services. all facets of the private sector--from large and small industries, research organizations, academia, private en- NASA inventions are available trepreneurs, and inventors. for licensing. The TU Office can direct you to patent counsels Tile TU Office will consider requests who can license NASA patents. for help with industrial or technical • A textile mill experienced problems or for information in a spe- NASA Tech Briefs magazine is frequent power surges that dam- cific technical field. Additionally, free to qualified business, techni- aged equipment. MSFC led a the TU Office will accept proposals cal, and academic professionals. team that solved the problem. for cooperative projects where the The TU Office can provide Government joins with private com- subscription information. * MSFC developed expert systems panies or organizations to modify to aid the design of superplastic space technology for other uses. NASA Center for Aerospace forming have been sought by Within these projects, proprietary Information (CASI) provides and supplied to industry. information is honored and patent technical support packages that . Environmental concerns lead to rights are negotiated to benefit the contain additional information to numerous requests for chloro- private-sector partner. supplement NASA Tech Briefs. fluorocarbon (CFC) substitutes.

The TU Office has access to a MSFC experience with substi- tutes for foaming, cleaning, and nationwide technology transfer Federal Laboratory Consortium network. Some of the services (FLC) can be your doorway to refrigeration products has been available include: more than 700 federal institu- compiled in Focus on the Future, tions and their technology a publication available through the TU Office. Computer Software Management expertise. and Information Center • One of the world's largest indus- (COSMIC ®) through which When NASA-developed technology trial computed tomography sys- computer programs from NASA is used for secondary applications, tems has been used by the and other federal agencies are everyone benefits. logging, energy, and automotive available for commercial use. industries for nondestructive inspection and testing. A manufacturer of compressors experienced a high rejection rate • Water-jet stripping technology of hermetically sealed units. developed at MSFC has resulted MSFC assisted in applying auto- in the fomlation of a private mated, laser-guided welding. company that has sold units to the airline and other industries.

A Tennessee manufacturer of • MSFC expertise in field testing electric motors experienced pro- resulted in the successful design duction and quality control prob- of test procedures to simulate lems. An MSFC engineer take-off and landing pressures suggested designs to improve on composite aircraft ducting the manufacturing process. needed by a small Alabama firm.

197 Small Business sponsored by the Federal government Innovation Research and performed by small businesses. Structured in three phases, the SBIR Program program uses Phase I to assess the technical feasibility of novel ideas proposed by small companies and The Small Business Innovation Phase 1I to conduct R&D on the best Research (SBIR) program offers an- concepts. Phase III, not funded by other avenue to access technology SBIR, is the utilization and/or com- transfer. The SBIR program objec- mercialization phase. tives include: stimulating technologi- cal innovation in the private sector, Some examples of products produced strengthening the role of small busi- under the SBIR program include: ness concerns in meeting federal Publications available through the research and development needs, SBIR program are: "Dry-Film Lubricant for Bearings increasing commercial application of Using Ion Implantation," which • Annual NASA SBIR solicitation for federally supported research results, has applications in orthopedic each program year, which speci- and fostering and encouraging par- fies the application requirements ticipation by socially and economi- implants, aerospace bearings, and semiconductor wafers. and describes the R&D of interest cally disadvantaged persons and women-owned small business in to NASA for that particular pro- technological innovation. "Control of Manual Data Entry gram year. Accuracy in Management and • The NASA SBIR Product Catalog One major national objective for the Engineering Information Systems," of products that have been pro- SBIR Program is broad commercial in business practice, can be used applications for the results of re- in tasks where at least 2,000 char- duced as a result of projects sup- search and development (R&D) acters of data per day are manu- ported under the SBIR program. ally entered into computers or This catalog assists small business reviewed by management for ac- firms in making the community curacy or sign-off. Other applica- aware of products emerging from tions are education curriculum their efforts in the SBIR program.

development and textbook pub- • Abstracts of Phase IProjects de- lishing for unified keyboarding, scribes the objectives of projects in personnel management, and placed under contract by the in psycho-medical research. NASA SBIR program within a specific program year. "Tethered Satellite Video Monitor- ing System" applications include • The NASA SBIR Composite List of space flight hardware, remote Projects includes all projects, both monitoring and security systems, Phase I and Phase lI, selected for and environmental monitoring. funding by the SBIR program.

Small Business Innovation Research Technology Utilization

Helen Stinson, SBIR Program Manager Ismail Akbay, Director Mail Stop ER41 Mail Stop AT01 Marshall Space Flight Center, AL 35812 Marshall Space Flight Center, AL 35812 205-544-7239 Toll Free: 1-800-437-5186 Commercial: 205-544-2223 FAX: 205-544-3151

198 Abbreviations and Acronyms

1N synchronous CASI Center for Aerospace Information 2N two-times synchronous CAVE Computer Applications and Virtual 2-D two dimensional Environments _DSRC Two-Dimensional Stability Research CCD charge coupled device Combustor Cd-An-Te cadmium zinc telluride 3--D three dimensional CDR Critical Design Review 4-D four dimensional CDRA Carbon Dioxide Removal Assembly 5-D five dimensional CERN European Center for Nuclear Research AAP Advanced Automation Project CES Conical Earth Sensor ABP ambient back pressure CFC chlorofluorocarbon ac alternating current CFD computational fluid dynamics AFM atomic force microscope CFM cryogenic fluid management Ag silver CGF Crystal Growth Furnace AGC automatic gain control CGRO Compton Gamma Ray Observatory AGG advanced gas generator CIRS Composite Infrared Spectrometer AGU American Geophysical Union CMV cloud motion vector AIAA American Institute of Aeronautics CO 2 carbon dioxide and Astronautics COARE coupled ocean-atmosphere response AIChE American Institute of Chemical experiment Engineers CORSS Cylinder Optimization of Rings, Skin, AlP Algorithm Intercomparison Project and Stringers AI20 _ gamma-aluminum oxide COSMIC ® Computer Software Management and AM acrylic model Information Center AMMC advanced main combustion chamber CPF cumulative percent frequency AMPR Advanced Microwave Precipitation CPU central processing unit Radiometer CRF cloud radiative forcing AMS American Meteorological Society CRIMS Cometary Rendezvous Ion Mass AMU atomic mass unit Spectrometer AOCI Advanced Ocean Color Imager CSI control/structure interaction AP ammonium perchlorate CSWA conic section wave approximation Ap. J. Astrophysics Journal CTV cargo transfer vehicle AS ammonium sulfate Cu copper ASEE American Society of Electrical Engineers DAAC Distributed Active Archive Center

ASME American Society of Mechanical DAM doubly aluminized Mylar TM Engineers dc direct current ATD alternate turbopump development DCR Data Control Room ATLAS Atmospheric Laboratory for DE Dynamics Explorer Applications and Science DIF Differential Ion Flux ATM Apollo Telescope Mount DIFP Differential Ion Flux Probe AU astronomical units DMSP Defense Meteorological Satellite Program AVHRR Advanced Very High Resolution DOT Design Optimization Tool Radiometer DSDS data systems dynamic simulator BATSE Burst and Transient Source Experiment DV dependent variable BFC body-fitted coordinates EB electron beam BRDF bidirectional reflectance distribution ECLSS Environmental Control and Life Support function System C-BIT conical bond-in-tension ECMkVF European Center for Medium Range CAD computer aided design Weather Forecasts CAGI computer aided grid interface EDCS Electrostatic Deflection and Collimation CAM computer aided manufacturing System CaPE Convective and Precipitation/ ELV expendable launch vehicle Electrification ENO essentially nonoscillatory

199 EOF Empirical Orthogonal Functions GPIB general purpose interface bus EOS Earth Observing System GPS Global Positioning System EOSDIS Earth Observing System Data and GRAM Global Reference Atmosphere Model Information System GSF Goddard Space Flight Center EP Earth Probe GTAW gas tungsten arc welding EPA Environmental Protection Agency H hydrogen EPDM ethylene propylene diene monomer H ÷ singly ionized hydrogen EPS Electrical Power System H 2 slush hydrogen ESA European Space Agency H20 water ESCA electron scanning analysis HBP high back pressure ET external tank HCFC hydrofluorocarbon EUV extreme ultraviolet HCI human-computer interface EVA extravehicular activity HDF hierarchial data format EST Experiments Systems Test He+ singly ionized helium EXVM Experimental Vector Magnetograph He++ doubly ionized helium FARE Fluid Acquisition and Resupply Hg-Cd-Te mercurous cadmium telluride Experiment Hg-Zn-Te mercurous zinc telluride FASTRAN Fast Transient Analysis HIFI high-frequency intrinsic FCT flux-corrected transport HIV human immunodeficiency virus Fe iron HNC heavy nuclei collector FEL free electron laser HOSC Huntsville Operations Support Center FELES front end load enabler schedule HPOT high-pressure oxidizer turbine FEREBA Flexibility Enhanced Rolling Element HPOTP high-pressure oxidizer turbopump Bearing Analysis HST Hubble Space Telescope fgr face growth rate HTPB hydrozy-terminated polybutadiene FLC Federal Laboratory Consortium IAU International Astronomical Union FMLI foam/multilayer insulation ICD Interface Control Document FOV field of view 1CRC International Cosmic Ray Conference FPC forty-pound charge IFOV instantaneous field of view FRACIE Frequency Response of Admittance IGES Initial Graphics Exchange Specification of Coaxial Injector Elements IMI Inner Magnetosphere Imager FRAMES fault recovery and management expert In-Sb indium antimonide system I/O input/output FRF frequency response function IPCL instrumentation program and command FTIR Fourier Transform Infrared list ftp file transfer protocol IR infrared g gravity IR&D independent research and development G_T Generic Gas Generator Turbine IRTF Infrared Telescope Facility Ga-As gallium arsenide ISCCP International Satellite Cloud Climatology Ga-In-Sb gallium indium antimonide Project GASP General Aerodynamic Simulation ISO Imaging Spectrometric Observatory Program ISO Infrared Space Observatory GCIP GEWEX Continental International Project ITCZ Intertropical Convergence Zone GEO Geostationary Earth Observatory IV independent variables GEOSIM Geophysical fluid flow simulator JACEE Japanese-American Cooperative GEWEX Global Energy and Water Cycle Emulsion Experiment Experiment JANNAF joint Army, Navy, NASA, and Air Force GFFC Geophysical Fluid Flow Cell JPt Jet Propulsion Laboratory GGOT Gas Generator Oxidizer Turbine JSC Johnson Space Center GGS Global Geospace Science KANT knowledge and negotiation tool GH 2 gaseous hydrogen KAO Kuiper Airborne Observatory GHe gaseous helium KNOMAD knowledge management and design GL Graphics Language KO knock on GLOBE Global Backscatter Experiment KSC Kennedy Space Center GN&C guidance, navigation, and control LAD liquid acquisition device GN 2 gaseous nitrogen LAMPS Limited Area Mesoscale Prediction GOES Geostationary Operational System Environmental Satellite LaRC Langley Research Center

200 LAWS Laser Atmospheric Wind Sounder NEAT noise equivalent change in temperature LDEF Long Duratkm Exposure Facility NESDIS Natkmal Environmental Satellite Data LDV Laser Doppler Velocimetry and Information Service LED light-emitting diode NGDC National Geophysical Data Center LEIF Low Energy km Facility NIR near infrared LEO low-Earth orbit NITM nozzle insulation test motor LeRC Lewis Research Center NLS National Launch System LGS laser glazed surface NMR nuclear magnetic resonance LH 2 liquid hydrogen NOAA National Oceanic and Atmospheric lidar light detection and ranging Administration LIS Lightning Imaging Sensor NTrC National Technology Transfer Center LLB leak before burst NURBS nonuniform rational b-spline LLP lowest level processor O* singly ionized oxygen LMS Lightning Mapping Sensor O *÷ doubly ionized oxygen LN 2 liquid nitrogen ODP ozone depletion materials LO lift-off OH hydroxyl LON local operating network OLS Optical Linescan System LOPC laser optical particle counter OMS Orbital Maneuvering System lox liquid oxygen OPB oxidizer preburner LSS large space structures OPS optical pulse sensor LTC low thermal conductivity OSHA Occupational Safety and Health Act LUTE Lunar Ultraviolet Telescope Experiment OSS Office of Space Science MACAWS Multicenter Airborne Coherent OTD Optical Transient Detector Atmospheric Wind Sensor PAN polyacrykmitrile MAMS Multispectral Atmospheric Mapping PAO Public Affairs Office Sensor PCA Payload Control Area MAPO magnetically actuated propellant PCTC Payload Crew Training Complex orientation PDCU power distribution control unit MAS MODIS--N Airborne Simulator pdf probability density function MCC main combustion chamber PDPA phase Doppler particle analyzer MET Marshall Engineering Thermosphere PGSC Payload and General Support Computer MHTB Multipurpose Hydrogen Test-Bed PHOT Photopolarimeter Instrument MLE Mesosphere Lightning Experiment PI principal investigator MLI multilayer insulation PIP Precipitation Intercomparison Project MLT magnetic local time PISO pressure-implicit split operator MLT mesosphere/lower thermosphere PLIF planar laser-induced fluorescence MNASA modified NASA PLM Pressurized Logistics Module Mo molybdenum PMAD power management and distribution MOC method of characteristics PMG Plasma/Motor Generator MSAD Materials Science and Applications PMW pulse width modulation Division POCC Payload Operations Control Center MSA Marshall sprayable ablator POIC Payload Operations Integratkm Center MSFC Marshall Space Flight Center PRM Performance Reconciliation Model MSU Microwave Sounding Unit Qvs quick-view systern MSV Mechanisms of Solar Variability R&D research and development MTPE Mission to Planet Earth Ra Rayleigh number MUSCL monotonic upstream schemes for radar radio detection and ranging conservation laws RAM random access memoD"

N + singly ionized nitrogen REFLEQS reactive flow equation solver

N ÷÷ doubly ionized nitrogen RGA residual gas analyzer NaCI sodium chloride RIMS Retarding Ion Mass Spectrometer NASA National Aeronautics and Space RMS radian mean per second Administration RMS Remote Manipulator System NASCRAC NASA Crack Analysis Code ROPE Research on Orbital Plasma Nb niobium Electrodynamics NCSA National Center for Supercomputing RPA retarding potential analyzers Applications RPC remote power controllers NDE nondestructive evaluation RSRM redesigned solid rocket motor

201 RTEP real-time event processor TA antenna temperature RTG radioisotope thermoelectric generator Ta tantalum RTLS return-to-launch site TABI tailored advanced flexible blanket RTFC Regional Technology Transfer Center insulation RWA rectangular wave approximation TB brightness temperature SAA South Atlantic Anomaly TCS thermal control system SAC sample ampoule cartridge TDK two-dimensional kinetics SAE Society of Automotive Engineers THC Temperature and Humidity Control SAFD system for anomaly and failure detection TIDE Thermal Ion Dynamics Experiment SAFiRE Sensing and Force-Reflecting TIMED Thermosphere, Ionosphere, Mesosphere, Exoskeleton Electro-Dynamics SAMPE Society for Manufacturing and Process TIROS Television Infrared Operations Satellite Engineering TMS Thematic Mapping Sensor StuMS signal analysis and modeling system TOF time of flight SBIR Small Business Innovation Research TOGA Tropical Ocean Global Atmosphere SCN succinonitrile TOVS TIROS Operational Vertical Sounder SCSI Small Computer Systems Interface TPS thermal protection system SEDS Small Expendable Deployer System TQCM temperature-controlled quartz crystal SEDSAT Students for the Exploration and microbalances Development of Space Satellite TRL technology readiness level SELENE Space Laser Energy TRMM Tropical Rainfall Measuring Mission SFMD Space Fluid Management Demonstration TSS Tethered Satellite System SGI Silicon Graphics, Inc. TSTO A/R two-stage-to-orbit: air breathing plus Si silicon rocket SiC silicon carbide TSTO two-stage-to-orbit SIMPLEC semi-implicit method for pressure linked TFA turbine test article equations TFB Technology Test-Bed SINDA systems improve numerical differencing TIE turbine test equipment analyzer TU Technology Utilization SMEX Small Explorer TUFI toughened rigid ceramic insulation SMM Solar Maximum Mission TVC thrust vector control SMMR Scanning Multichannel Microwave TVD total variation diminishing Radiometer TVS themaodynamic vent system SNR signal-to-noise ratio TWA triangular wave approximation SOFI spray-on foam insulation U of I University of Illinois SOURCE Solar Ultraviolet Radiation and UARS Upper Atmosphere Research Satellite Correlative Emissions ULC Unpressurized Logistics Carrier SPES Soft Particle Energy Spectrometer USBI United Space Boosters, Inc. SPIE Society of Photo-Optical Instrumentation USI USBI Sprayable Insulator Engineers USML United States Microgravity Laboratory SPIP Solid Propulsion Integrity Program UTSI University of Tennessee Space Institute SPN Shared Processing Network UV ultraviolet SRM solid rocket motor UVI Ultraviolet Imager SS Sun Sensor VAS visible infrared spin-scan radiometer SSF silicone seal material atmospheric sounder SSM space station module VDCR Virtual Data Control Room SSM/I Special Sensor Microwave Imager VI virtual instrument SSME space shuttle main engine VPOCC Virtual Payload Operations Control SSR solid state recorder Center SST sea surface temperature VPPA variable polarity plasma arc SSTO A/R single-stage-to-orbit: air breathing VPS vacuum plasma spraying plus rocket VR virtual reality SSTO R single-stage-to-orbit: all rocket VW virtual world SSTO single-stage-to-orbit W tungsten STME space transportation main engine WMO World Meteorological Organization STORM-FEST Storm-Scale Operations and Research XTM X-ray Transmission Microscope Meteorology-Fronts Experiment Zr zirconium System

202 Index of Contacts

Abbas, Mian M. Infrared Spectroscopy of the Earth's Upper Atmosphere and Planetary Atmospheres ...... 75

Anderson, B. Jeffrey Theromospheric Density Variations Simulator ...... 191

Austin, Gene Access to Space: Advanced Technology Vehicle (Option 3) Focused Technology/Advanced Development Plan ...... 14

Benjamin, Theodore G. Computer Aided Grid Interface System ...... 155

Bhat, Biliyar N. Beam Processing of NARIoy-Z for Improved Microstructure, Properties, and Life Enhancement of Main Combustion Chamber Liner ...... 108

Blakeslee, Richard J. Aircraft Investigations of Lightning and Thunderstorms ...... 40

Bookout, Paul S. Analysis of Residual Flexibility Modal Test Data ...... 157

Bordelon, Wayne J., Jr. Investigation of Inducer Cavitation and Blade Loads ...... 159

Braam, Fred W. Formed Platelet Combuster Liner Construction Feasibility ...... 133

Bridge, Scott L. Mass Data Storage Unit ...... 96

Butas, John P. Systematic Data Reconciliation in Rocket Engine Performance Predictions ...... 136

Butler, John M., Jr. Space Station Advanced Programs ...... 9 Tether Applications in Space ...... 10

Cardno, Amy N. Monitoring and Diagnosing the Environmental Control and Life Support System ...... 97

Carrasquillo, Robyn L. Bosch Reaction Kinetics Research ...... 160

Cash, Martha B. Electromechanical Propellant Control Valve Actuator ...... 146

Chandler, Michael O. Two-Dimensional Motion of Oxygen Ions in Earth's High-Latitude Ionosphere ...... 63

Christian, Hugh J. Lightning Imaging Sensor ...... 41

Clinton, Raymond G. Development of Low Thermal Conductivity PAN-Based Fibers for SRM Nozzle Applications ...... 120

Coffey, Victoria N. Application of Automated Data Acquisition to the Low-Energy Ion Facility ...... 71

Cozelos, Charles L. Modular Software for Engine Control ...... 96

Craven, Paul D. Minor Ion Contributions to the Ionosphere and Magnetosphere ...... 67

Curreri, Peter A. Real-Time X-Ray Microscopy of Solidification Processes ...... 88

Dabbs, Joseph R. Solar Ultraviolet Radiation and Correlative Emissions ...... 5

Davis, John M. The Mechanisms of Solar Variability--A Study of the Origins of the Variability of the Solar Output ...... 44

Dennis, Henry J. Advanced Main Combustion Chamber Development ...... 132

Derrickson, James H. The Observation of Direct Electron-Positron Pairs by Relativistic Heavy Ions in Nuclear Emulsion ...... 81

DeSanctis, Carmine E. Inner Magnetosphere Imager Mission ...... 3 Solar Ultraviolet Radiation and Correlative Emissions ...... 5

Dewberry, Brandon S. Monitoring and Diagnosing the Environmental Control and Life Support System ...... 97

Dowdy, James F., Jr. Understanding the Quiet Solar Transition Region--The Source of Solar Ultraviolet Radiation ...... 53

203 Dugal-Whitehead, Norma Space Station Module Power Management and Distribution Automated Subsystem ...... 100

Edwards, David L. Approximation Techniques to Determine the Increase in Surface Area Due to Surface Roughness ...... 106

Facemire, Barbara R. Kinetics of Diffusional Droplet Growth in a Liquid/Liquid Two-Phase System ...... 90

Finckenor, Jeffery Cylinder Optimization of Rings, Skin, and Stringers ...... 160

Finckenor, Miria M. Long Duration Exposure Facility Experiments and Space Environment Effects on Materials Studies ...... 104

Fishman, Gerald J. Burst and Transient Source Experiment Observations of Gammay-Ray Bursts ...... 79

Fitzjarrald, Daniel E. Global Atmospheric Modeling ...... 26

Ford, Donald B. Optimum Design of Launch Vehicle Structures ...... 163

Fox, Thomas H. System for Anomaly and Failure Detection ...... 164

Gaddis, Stephen W. Cold Air Flow Turbine Testing of Advanced Turbine Designs ...... 166

Gallagher, Dennis L. A Cleft Ion Fountain Model ...... 65

Garcia, Roberto Pump Computational Fluid Dynamics Code Validation Tests ...... 168 Hydrodynamic Design of Advanced Pump Components ...... 169

Gary, Gilmer A. Solar Magnetic Fields ...... 45

Genge, Gary G. Compliant Foil Bearing Technology Demonstration ...... 143

Giles, Barbara L. The Ionosphere as an Alpha Particle Source ...... 62

Goodman, H. Michael Earth Observing System Pathfinder Passive Microwave Data Set Production ...... 30

Goodman, Steven J. Defense Meteorological Satellite Program Optical Linescan System Data System Global Survey of Lightning ...... 22

Graham, Benny F. Forming of Aluminum-Lithium and High Aspect Ratio Orthogrid Panels ...... 111

Gregg, M. Wayne Elastic-Plastic Fracture Mechanics Methodology for Surface Cracks ...... 170 Elastic-Plastic and Fully Plastic Fatigue Crack Growth ...... 171

Griffin, Lisa W. Advancement of Volute Design Techniques ...... 172 Development of Advanced Turbine Blades ...... 174

Hale, Joseph P., II Virtual Reality Applications Program ...... 126 A Dynamic Human-Computer Interface Prototyping Environment With Embedded Evaluation Capability ...... 129

Harmon, B. Alan Discovery of X-Ray Nova Persei 1992 (GRO J0422+32) With the Burst and Transient Source Experiment ...... 84

Harrison, James K. Small Expendable Deployer System ...... 12

Hathaway, David H. Long-Term Solar Activity Predictions ...... 48

Hayes, Benita C. Alternative Illumination Technologies for the Human Habitation of Space ...... 131

Hood, Robbie E. The Advanced Microwave Precipitation Radiometer ...... 36

Hutt, John J. Liquid Rocket Injector Characterization ...... 133

Inman, Kaye Protein Crystal Analysis Equipment ...... 13

James, Mark W. Multispectral Atmospheric Mapping Sensor ...... 37 Sensor Development: Lightning Imaging Sensor Calibration ...... 42

Jarzembski, Maurice A. Global Aerosol Backscatter Experiments ...... 24

Johnson, C. Les Inner Magnetosphere Imager Mission ...... 3

Kavaya, Michael J. Solid-State Coherent Doppler Lidar ...... 98

204 Keller, Vernon W. Geostationary Earth Observatory Program ...... 6 A Long Duration Exposure Facility Folk)w-On Spacecraft Concept ...... 10

Koczor, Ronald J. Advanced Technologies for Geostationary Orbit Remote Sensing ...... 43

Koshak, William J. Lightning Radiative Transfer Inversion Studies ...... 21

Lapenta, William M. Mesoscale Modeling Related to the Hydrologic Cycle ...... 20

Lawless, Kirby G. New Weld Controller Nearing Completion, and Welding Pendant Incorporates New Technok)gies ...... 112

Lee, Henry M. Verification of Analytical Methods--Single Cycle Versus Multicycle Proof Testing ...... 176

Leslie, Fred W. Geophysical Fluid Flow Cell Experiment ...... 34

Lester, Carl N. Environmentally Friendly Sprayable Ablator for the Solid Rocket Booster ...... 124

Linton, Roger C. Long Duration Exposure Facility Experiments and Space Environment Effects on Materials Studies ...... 104 Optical Effects Facility ...... 108

Litkenhous, Edward E., Ill Low-Temperature Testing of Static Seals and Leakage Characterization ...... 144

Lomas, James J. Autonomous Reconfigurable Navigation and Attitude Filter ...... 189

Marsh, Matthew W. Low-Cost Turbomachinery Technology ...... 142

Martinez, Nelson G. Enhanced Capabilities of an Electrostatic Deflection and Collimation System ...... 73

McBrayer, Robert O. Astrophysics--Lunar Ultraviolet Telescope Experiment ...... 2

Meyer, Paul J. Four-Dimensional Interactive Analysis Capability ...... 31

Miller, Timothy L. Numerical Modeling of Nonlinear Baroclinic Fluid Systems ...... 18

Montgomery, Edward E. Space Laser Energy ...... 7

Moore, Ronald L. Corona and Solar Wind ...... 47

Moore, Thomas E. Substorm-Genemted Impulsive Plasma Flows ...... 55 Mass Spectrometer Resolution Enhancement Using an Electrostatic Lens ...... _7 The Ionosphere as an Alpha Particle Source ...... 62 Two-Diminsional Motion of Oxygen Ions in Earth's High-Latitude lonsphere ...... 63

Nein, Max E. Astrophysics--Lunar Ultraviolet Telescope Experiment ...... 2

Noever, David A. Highly Rarefied Solids in Microgravily: Toward the Limits for a Solid With Zero Volume and Infinite Surface Area ...... 93

Nolen, Angela R. Novel Material Concepts for Spacecraft Debris ...... 105

Ortega, Rene Fracture Control/Damage Tolerance Methods for Composite/Anisotropic Materials ...... 176

Otte, Neff E. Cylinder Optimization of Rings, Skin, and Stringers ...... 160

Owens, Jerry K. Imaging the Auroral Oval at Vacuum Ultraviolet Wavelengths ...... 76 Spectroscopy of the Mesosphere and Thermosphere From the Space Shuttle ...... 77

Parker, James w. Signal Analysis and Modeling System ...... 189

Parnell, Thomas A. Cosmic Ray Proton Specmtm Changes at 4×1() _ Electronvolts ...... 83

Perry, Jay L. Study of Trace Contaminant Control System Catalysts ...... 177

Pollock, Craig J. Application of Focusing Electrostatic Mirrors to a Spaceborne Ion Mass Spectrometer ...... 59

Poorman, Richard M. Vacuum Welding and Brazing for Space Applications ...... 110 Thermal Spray Forming of Refractory Sample Ampoule Cartridges for Single Crystal Growth Space Furnaces ...... 112

Price, .tohn M. Grid Optimization Tools for Complex Models ...... 181

205 Pusey, Marc L. The Effects of Temperature on Tetragonal Lysozyme Face Growth Rates ...... 89

Ramsey, Brian D. X-Ray Astronomy Research ...... 80

Razvi, Shakeel S. Hybrid Capacitive-Inductive Microsensor Arrays for Evaluating the Integrity of Thermal Barrier Coatings ...... 101

Rhodes, Percy H. Separation of Large DNA Molecules in Free Fluids ...... 92

Roberts, Floyd E. III Torch-Produced Diamond Films ...... 119

Robertson, Franklin R. Diagnostics of the Global Hydrologic Cycle ...... 19

Rocker, Marvin Combustion Stability Testing and Analysis ...... 140

Rodriguez, Pedro I. Augmented Orbital Debris Shield Concepts for Space Station Critical Elements ...... 187 Quantifying Spacecraft Crew Safe W From Orbital Debris Penetration ...... 187

Rogers, Patrick R. Cylinder Optimization of Rings, Skin, and Stringers ...... 160

Rothermel, Jeffry Multicenter Airborne Coherent Atmospheric Wind Sensor ...... 38

Rupp, Charles C. Tether Applications in Space ...... 10

Russell, Samuel S. Hybrid Capacitive-Inductive Microsensor Arrays for Evaluating the Integrity of Thermal Barrier Coatings ...... 101

Ryan, Stephen G. Dynamic Modeling of Bearings ...... 178

Schafer, Charles F. Liquid Rocket Injector Characterization ...... 133

Schmidt, George R. Multipurpose Hydrogen Test-Bed ...... 147 Combined Foam/Multilayer Insulation Demonstration ...... 149 Fluid Acquisition and Resupply Experiment ...... 151 Liquid Acquisition Device Characterization ...... 152 Magnetically Actuated Propellant Orientation ...... 153

Semmel, M. Louise Environmental Replacement Technology: Aqueous Cleaners, Primers, and Adhesives for SRM Cases ...... 116 Development of an Advanced Solid Propellant Simulant ...... 117

Smith, Andrew W. Porous Wall Flow Experimental Facilities ...... 178

Spencer, Roy W. Global Climate Monitoring From Satellites ...... 34

Stallworth, Roderick Verification of Analytical Methods: NASA Crack Analysis Code ...... 180

Stone, Nobie H. The Tethered Satellite System-1 Research on Orbital Plasma Electrodynamics Investigation ...... 68

Suess, Steven T. The Effect of Solar Wind Changes on the Heliospheric Termination Shock ...... 50

Suggs, Ronnie J. Evaluation of Thermosphere Density Models ...... 32

Susko, Michael Spatial/Temporal Variabili w of Wind Fields for Design of Remote Sensors ...... 27

Swanson, Gregory R. Grid Optimization Tools for Complex Models ...... 181

Taylor, Kenneth R. Protein Crystal Analysis Equipment ...... 13

Telesco, Charles M. Infrared Space Astronomy and Space Research ...... 86

Tinker, Michael L. Analysis of Residual Flexibility Modal Test Data ...... 157

Trinh, Diep V. New Direction in Phthalocyanine Pigments ...... 114

Trinh, Huu P. High Mixture Ratio Core Gas Generator Analysis ...... 139

Tucker, P. Kevin Combustion Chamber Analysis Code ...... 183 High-Accuracy Computational Fluid Dynamics Methodology for Fast Flow Transients and Nonlinear Instability Phenomena ...... 182

Tygielski, Kathy S. Advanced Main Combustion Chamber Development ...... 132

206 Upton,CindyG. CarbonPhenolicAblativeMaterialsTestMethodology...... 118 Vaughan,OthaH.,Jr. SpaceShuttleLightningResearch...... 39 Vickers,JohnH. FiberPlacement:NewTechnologyforAutomatedCompositeManufacturing...... 124 Volz,MartinP. ElectromagneticFieldEffectsin SemiconductorCrystalGrowth...... 88 Walls,BryanK. SpaceStationModulePowerManagementandDistributionAutomatedSubsystem...... 100 Wang,TenSee AGeneralComputationalFluidDynamicsCodeforAll MachNumbers...... 184 FastAlgorithmCombustionModeling...... 186 Weaver,EdwinA. EnhancedAerospaceInsulationSystems...... 123 Weir,RaeAnn High-PowerElectromechanicalThrustVectorControlActuators...... 146 Weisskopf,MartinC. X-RayAstronomyResearch...... 80 Wertz,GeorgeE. FormabilityStudyofAerospaceAluminumAlloys...... 102 Whitaker,AnnF. LongDurationExposureFacilityExperimentsandSpaceEnvironmentEffects on MaterialsStudies...... 104 Whorton,MarkS. HubbleSpaceTelescopePointingControllerRedesign...... 186 Williamsen,JoelE. AugmentedOrbitalDebrisShieldConceptsforSpaceStationCriticalElements...... 187 QuantifyingSpacecraftCrewSafetyFromOrbilalDebrisPenetration...... 187 Wright,MichaelD. Saluteto SkylabandSpacelab--TwoDecadesof Discovery...... ix Zimmerman,FrankR. ThermalSprayFormingof RefractorySampleAmpouleCartridgesforSingleCrystal GrowthSpaceFurnaces...... 112 Zwiener,JamesM. NovelMaterialConceptsforSpacecraftDebris...... 105

207 Index of Key Words

About Key Words blowing agent ...... 123 bond ...... 116 To broaden the availability of this report, the text is placed on-line on the FEDIX Technology Information bonding agents ...... 117 System computer, which can be easily accessed by Bosch CO 2 reduction ...... 160 phone and terminal. This enhances the opportunities brown dwarfs ...... 86 for technology transfer to the private sector. bubble-point pressure ...... 153 For further information about FEDIX, contact.. Burst and Transient Source Experiment (BATSE) ...... 79 calibration facility ...... 42 Office of the Associate Director for Science carbon fibers ...... 120 Mail Stop DS01 Marshall Space Flight Center, AL 35812 carbon phenolic materials ...... 118, 119 205-544-3033 catalyst ...... 177 cavitation ...... 159 CFD ...... 155, 156, 168, 169, 172, 173, 174, ablatives ...... 120, 122 182, 183, 184, 186 ablator ...... 124, 125 CGIP ...... 20 acceptance tests ...... 118, 119 charge coupled device (CCD) ...... 42 actuation ...... 146 chlorinated hydrocarbon ...... 124

Ada TM ...... 96 climate ...... 26, 38 adaptive optics ...... 7 climate change ...... 26 Advanced Microwave Precipitation cloud-to-stratospheric lightning ...... 39 Radiometer (AMPR) ...... 36 coating ...... 107 Advanced Ocean Color Imager (AOCI) ...... 37 combustion ...... 140, 141, 182, 183, 186 advanced main combustion chamber ...... 132 combustion chamber ...... 133 AlDen waves ...... 47, 48 commands ...... 189 alpha particles ...... 62, 63 compliant foil bearings ...... 143 altitude aircraft ...... 36 composite manufacturing ...... 124 aluminum-lithium ...... 111 composite/anisotropic materials ...... 176, 177 ambient illumination ...... 131 Compton Gamma Ray Observatory (CGRO) ...... 79 analysis ...... 136, 137 computational fluid dynamics ...... 172, 174, 186 analysis model ...... 105 computer models ...... 18 approximation ...... 107 condensation ...... 152, 153 atmosphere ...... 18, 34, 35 constraint ...... 170, 171 atomic force microscope ...... 119 contaminants ...... 177 atomic oxygen ...... 104 contamination ...... 108 atomization ...... 133, 135 control ...... 96, 146 aurora ...... 76 control system design ...... 186 automated ...... 112 controller ...... 112 automated fiber placement ...... 124 convection ...... 34, 35 automation ...... 72 cooling liner ...... 133 backscatter ...... 24, 25 cosmic rays ...... 83 baroclinic ...... 34, 35 Coupled Ocean-Atmosphere Response Experiment BATSE ...... 84, 85, 86 (COARE) ...... 36 bearings ...... 178 crack closure ...... 171, 172 benchmarked ...... 168 crewed spacecraft ...... 187 bidirectional reflectance ...... 108 cryogenic fluid management ...... 147 black hole ...... 85, 86 Crystal Growth Furnace ...... 112

208 crystal ...... 89, 90 forming limit ...... 102, 103 crystal growth ...... 89, 112, 113, 114 fractal ...... 93 crystalk)graphy ...... 13 fracture mechanics ...... 176, 180 damage tolerance ...... 176, 177 fracture toughness ...... 177 data ...... 189, 190 free electron laser ...... 7 debris shielding ...... 105 free fluid ...... 92 density variations ...... 191, 192 galaxies ...... 86, 87 design ...... 163, 164, 169, 170 gamma-ray bursts ...... 79 diamond ...... 119, 120 gas generator ...... 139, 140 direct electron-positron pairs ...... 81 gas generator oxidizer turbine ...... 172, 175 distortion ...... 169, 170 gas tungsten arc welding ...... 110 Distributed Active Archive Center (DAAC) ...... 30, 36 Gask-O-Seal ...... 144 distribution function ...... 108 GEO ...... 6 DNA ...... 92 GEO remote sensing ...... 43 Doppler lidar ...... 38 geometry ...... 155, 156 drought ...... 26 geophysical ...... 34 Earth ...... 67, 68, 84 Geostationary Operational Environmental Earth Observing System (EOS) ...... 42 Satellite (GOES) ...... 27 Earth Observing System (EOS) Data geostationary ...... 6 and Information System (EOSDIS) ...... 30 GEWEX ...... 20 Earth system ...... 19 glazing ...... 109 ECLSS ...... 9 Global Positioning System (GPS) ...... 189 efficiency ...... 174 gravity ...... 88 elastic-plastic fatigue ...... 171,172 grid ...... 155, 181 elastic-plastic fracture ...... 170 growth ...... 89, 90 electrical power system ...... 100 HCI ...... 129, 130 electrodes ...... 73, 74 HCI prototyping ...... 129, 130 electromagnetic ...... 88 HDF ...... 31 electromechanical ...... 146 high mixture ratio core ...... 139 electron beam ...... 109 high-speed processing electronics ...... 41 electrostatic ...... 59, 61 holography ...... 90 electrostatic lens ...... 57 human factors ...... 126, 127 enabling technologies ...... 14, 15 human-computer interface ...... 129 engine ...... 96 hydrodynamic bearing ...... 143 environmental control ...... 97 hydrologic cycle ...... 20 environmental regulations ...... 124, 125 hypervelocity impact ...... 102 environmentally friendly ...... 124, 125 hypervelocity penetration mechanics models ...... 102 evaporating spray ...... 186 IGES ...... 155, 156 evaporation ...... 152, 153 imaging ...... 3 expendable launch vehicles ...... 9 impeller ...... 168, 169 experiments ...... 10, 11 inducer ...... 159 fabrication ...... 133 inert propellant ...... 117, 118 face ...... 89, 90 Infrared Space Observatory (ISO) ...... 86 fault detection ...... 100 infrared (IR) ...... 86, 87 ferrofluid ...... 154 infrared spectrum ...... 75 flaw growth ...... 177 rejector ...... 133, 135 flow ...... 169 instability ...... 183 flows ...... 55, 56, 57 instrument ...... 59, 60, 61 foam ...... 123 insulation ...... 149, 150, 151 forecast ...... 26 insulator ...... 124 formed paltelet cooling liner ...... 133 interactive ...... 31 forming ...... 111 investment cast structure ...... 132

209 ionosphere ...... 57, 63, 64, 65, 77 MSFC Quick-View System (QVS) ...... 37 ionospheric source ...... 62 multicycle proof testing ...... 176 ions ...... 58, 63, 64, 67, 68 multilayer insulation ...... 147, 149 J-integral ...... 171,172 Multispectral Atmospheric Mapping Sensor JACEE ...... 83 (MAMS) ...... 37 kinetics ...... 119 NARIoy-Z ...... 108, 109 laboratory ...... 71 NASCRAC ...... 180 LAD ...... 151 navigation ...... 189 LAMPS ...... 20 neutral atoms ...... 3, 4 laser ...... 7, 8, 98, 99, 109 nozzle ...... 120, 122, 123 launch vehicle ...... 163, 164 nozzles ...... 118 LDEF ...... 10, 11, 32 O-ring ...... 144, 145 leak before burst ...... 171 occultation ...... 84 leakage characterization ...... 144, 145 operations cost ...... 15 lidar ...... 24, 25, 38, 98, 99 optical pulse sensor ...... 21 lighting ...... 131 Optical Transient Detector (OTD) ...... 40 Lightning Imaging Sensor (LIS) ...... 40, 41, 42 optimization ...... 160, 161, 163, 181 lightning ...... 21, 39, 40, 41 orbital debris ...... 105, 187 lightning discharge ...... 21 orthogrid ...... 111 lightning mapper sensor (LMS) ...... 40 Ostwald ripening ...... 90 lightning-like discharges ...... 40 oxidizer-rich turbine gas ...... 142 liquid acquisition device (LAD) ...... 151, 153 ozone depletion ...... 34 liquid oxygen ...... 153 paramagnetism ...... 153 liquid propellant ...... 133 Pathfinder, Earth Observing System (EOS) ...... 30 liquid rocket engine ...... 139 performance ...... 166, 167 Lite Sat ...... 5 performance predictions ...... 136, 138 Long Duration Exposure Facility ...... 10, 32, 104 phthalocyanine pigments ...... 114, 115 low-cost turbopump ...... 142 piezoelectric ...... 8 low-light-level TV cameras ...... 39 pixel ...... 42 Lunar Ultraviolet Telescope ...... 2 planetary atmospheres ...... 75 LUTE ...... 2, 3 plasma ...... 55, 56, 57, 59, 65, 66, 67, 73, 74 lysozyme ...... 90 platelet ...... 132, 133 magnetic field ...... 53, 54, 153, 154 platelet liner ...... 132 magnetosphere ...... 3, 4, 63, 65, 67, 68, 76 polar cap ...... 65, 66 magnetospheric plasma content ...... 62 polarimeter ...... 80 mass spectrometer ...... 59 polyacrylonitrile (PAN) ...... 120 materials processing ...... 89 porous wall flow ...... 178 mechanism ...... 146 power beaming ...... 7, 8 mesoscale ...... 38 precipitation ...... 22 mesoscale modeling ...... 20 preconditioning techniques ...... 184, 185 mesosphere ...... 77 pressure control ...... 147, 148 microgravity ...... 93 pressure vessels ...... 170, 171 microstructure evolution ...... 90 propellant ...... 117, 118, 146 mirror ...... 59, 60, 61 propellant reorientation ...... 154 Mission to Planet Earth ...... 6, 36, 43 proportional counter ...... 80 model ...... 136, 138 protein ...... 89, 90 model-based diagnosis ...... 97 protein crystal growth ...... 13 modeling ...... 90, 189 protons ...... 84 modern control theory ...... 186, 187 protoplanetary disk ...... 87 MODIS-N Airborne Simulator (MAS) ...... 37 pump ...... 159 molecular modeling ...... 115 quasi-static ...... 178 motors ...... 146 quench ...... 90

210 race flexibility ...... 178 space welding ...... 110 Radar Wind Profiler ...... 27 spacecraft ...... 10, 11 Radar/Jimsphere Wind System ...... 27 spacecraft lighting ...... 131 rainfall ...... 22, 34 Spacelab ...... 34 reaction kinetics ...... 160 Special Sensor Microwave/Imager (SSM/I) ...... 30 reconfigurable ...... 189 spectrometer ...... 61 redundancy ...... 189 spectroscopy ...... 77 reference stress ...... 171, 172 splash plate ...... 139, 140 relativistic cosmic rays ...... 82 SSM/PMAD ...... 9 remote sensing ...... 40, 77 SSME ...... 96, 164, 168 rendering ...... 31 stability ...... 140, 141 replacement materials ...... 116 static seals ...... 144, 145 research ...... 64 stellar winds ...... 47 residual flexibility ...... 157, 158 stiffened shells ...... 160, 161 resistance curves ...... 176 stiffness ...... 178 rocket ...... 96, 182 strategy ...... 181 rotor dynamic ...... 178 stress intensity ...... 180 substorm ...... 55, 56, 57 sample ampoule cartridge ...... 112, 114 scaled ...... 166 Sun ...... 45, 46, 50, 52, 53, 54 scattering ...... 108 sunspots ...... 48, 49, 50 screen ...... 151, 152 Sunyaev-Zel'dovich ...... 80 SEDS ...... 12 surface ...... 106, 107 semiconductor ...... 88, 112, 113, 114 surface cracks ...... 171 sensor ...... 101, 189 technologies ...... 6 separation ...... 92 temperature ...... 34 sheaths ...... 68, 69, 70 termination shock ...... 50, 51, 52 side loads ...... 172, 173 test article ...... 166, 167 Simplex ...... 142 test data ...... 136, 137 simulation ...... 73, 191, 192 test methodology ...... 118 single-stage-to-orbit ...... 14 testing ...... 166 skin-stringer ...... 160, 161 tests ...... 141 tether ...... 10, 12 Small Expendable Deployer System ...... 10, 12 Small Explorer ...... 5 tether applications ...... 12 software/hardware ...... 190 tether deployment ...... 12 solar activity ...... 48, 49 Tethered Satellite System ...... 10 solar corona ...... 47 tethers ...... 68, 69, 70 solar cycle ...... 32, 33, 48, 49, 50 Thematic Mapping Sensor (TMS) ...... 37 solar magnetic fields ...... 45, 46 thermal coatings ...... 101 solar variability ...... 45 thermal control systems ...... 147, 149 solar wind ...... 47, 48 thermocapillary flow ...... 152, 153 solar-stellar astrophysics ...... 47 thermosphere ...... 32, 33, 76, 77, 78, 191, 192 solid rocket motor (SRM) ...... 120, 122, 178 thrust vector control ...... 146 solid-state ...... 99 thundercloud ...... 21 solid-state recorder ...... 96 thunderstorms ...... 21, 41 solidification ...... 88, 89 TIMED ...... 5 soluble core ...... 106 torch-produced diamond ...... 119 SOURCE ...... 5 trace ...... 177 space ...... 10 trajectories ...... 64 transient ...... 183 space environmental effects ...... 11 space plasma ...... 68, 69 transition region ...... 53, 54 space shuttle main engine ...... 96 transitioning ...... 180 turbine ...... 174, 175 space station ...... 9, 187

211 turbomachinery ...... 142, 143, 167 Virtual Reality ...... 126 turbulence ring ...... 139, 140 Vis5D ...... 31 two-stage-to-orbit ...... 14 volcano ...... 34 UARS ...... 5 w_lute ...... 172, 173 ultraviolet (UV) ...... 3, 4, 53, 54 Voyager spacecraft ...... 50, 52 ultraviolet radiation ...... 104 VR ...... 126, 127, 128 uncertainty ...... 136, 137, 138 VR applications ...... 126, 127 usability testing ...... 130 VR validation ...... 128 vacuum plasma spray ...... 112, 113, 114 Weber number ...... 152 vacuum UV ...... 108 weighted curve fit ...... 158 vacuum welding ...... 110 welding ...... 112 vane ...... 151, 152 WETNET ...... 22 variable ...... 53 wind ...... 98, 99 vector magnetograph ...... 45 workstation ...... 156 vehicle health management and monitoring ...... 14 x ray ...... 3, 88, 89 velocity ...... 98 x-ray nova ...... 84, 86 vibration ...... 159 x-ray optics ...... 80, 81

212