Ames Research Center

Research and Technology NASA Ames Research Research and Technology

National Aeronautics and Space Administration Ames Research Center Moffett Field, California

NASA TM-112195 Foreword

The mission of NASA Ames Research Center is to research, develop, verify, and transfer advanced aeronautics, space, and related technologies; to advance and communicate scientific knowledge and understanding of the universe, the solar system, and the Earth; and to enable the development of space for human enterprise. Empha- sis is placed on information systems technologies for aeronautics and space applications; on aviation operations systems; and on the discipline of astrobiology, the study of life in the universe encompassing the Earth, space, and life sciences.

This report highlights the challenging work accomplished during fiscal year 1996 by Ames research scientists, engineers, and technologists. It discusses research and technologies that enable the Information Age, that expand the frontiers of knowledge for aeronautics and space, and that help to maintain U. S. leadership in aeronautics and space research and technology development. The accomplishments span the range of goals of NASA’s four Strategic Enterprises: Aeronautics and Space Transportation Technology, Space Science, Human Exploration and Development of Space, and Mission to Planet Earth.

The primary purpose of this report is to communicate information—to inform our stakeholders, customers, and partners, and the people of the United States about the scope and diversity of Ames’ mission, the nature of Ames’ research and technology activities, and the stimulating challenges ahead. The accomplishments cited illustrate the contributions that Ames is making to improve the quality of life for our citizens and the economic position of the United States in the world marketplace.

For further information on Ames research and technology projects, please contact the person designated as the point of contact at the end of each article. An electronic version of this report is available at URL http//jit.arc.nasa.gov/atrs/index.html.

Henry McDonald Director

ii ii C ONTENTS

Aeronautics Enterprise

Overview ...... 1

Global Civil Aviation/Safety

Aviation Performance Measuring System...... 3 Irving C. Statler Aviation Safety Reporting System ...... 4 Linda J. Connell Crew Activity Tracking System ...... 5 Todd J. Callantine Study of Line Oriented Flight Training ...... 6 Key R. Dismukes Measuring Air Traffic Complexity ...... 7 Irene V. Laudeman, Connie Brasil, Robert Branstrom Operational Interventions to Human Error in Aircraft Maintenance ...... 8 Barbara G. Kanki, Vicki Dulchinos Aircraft Separation Risk Model ...... 9 Mary M. Connors The Final Approach Spacing Tool ...... 11 Tom Davis Air/Ground Integration ...... 11 R. Slattery The Traffic Management Advisor...... 12 Harry N. Swenson Surface Movement Advisor ...... 13 Brian J. Glass Simplified Vision Models for Display Quality Assessment ...... 14 Al Ahumada Perceptually Tuned Visual Simulation ...... 15 Mary K. Kaiser Entropy Masking in Visual Displays...... 17 Andrew B. Watson Vertical Motion Simulator Advanced Simulator Network ...... 18 William B. Cleveland Intelligent Aircraft Control System ...... 19 Charles C. Jorgensen

iiiiii Aeronautics Enterprise (continued)

Global Civil Aviation/Affordability

Facilitating User Route Preferences in En Route Airspace ...... 20 Bob Vivona, Mark Ballin, Steve Green, Ralph Bach, Dave McNally Conflict Probability Estimation for Free Flight ...... 21 Russell A. Paielli, Heinz Erzberger Conflict Prediction Algorithms: Initial Field Test ...... 23 Dave McNally, Bob Vivona, Karl Bilimoria, Gerd Kanning, Steve Green, Ralph Bach, Allan McCrary, Ed Lewis Assessing Controller Performance Under Simulated Free-Flight Conditions ...... 24 Roger Remington, James Johnston, Eric Ruthruff, Maria Romera Evaluating Cockpit Display of Traffic Information Displays and Route Assessment Tools for a Free Flight Environment ...... 25 Vernol Battiste, Walter W. Johnson Cockpit Displays for Low-Visibility Taxiing ...... 27 David Foyle, Elizabeth M. Wenzel, Durand R. Begault Multi-Sensor Image Registration ...... 29 Misha Pavel, Al Ahumada, Barbara Sweet Flow Visualization of a Full-Scale Rotor in Hover ...... 29 Benton H. Lau, Alan J. Wadcock, Gloria K. Yamauchi Skin-Friction Measurements on a Hovering Rotor...... 30 Alan J. Wadcock, Gloria K. Yamauchi Rotor Data Correlation ...... 31 Randall Peterson Canard Rotor/Wing Hover Test ...... 32 Stephen Swanson, John Madden In-flight Dynamic Stall Research ...... 34 Robert Kufeld, William Bousman Stall Control of Helicopter Rotors ...... 34 Khanh Q. Nguyen Apache AH-64D Flight Test Predictions ...... 35 Earl P. N. Duque Rotor-Wake/Fuselage Interaction...... 36 Paul M. Stremel Navier-Stokes Simulation of High-Lift Aerodynamics ...... 37 Karlin Roth, Stuart Rogers Lift-Jet Effects on Powered-Lift STOVL Model ...... 38 Karlin Roth Vortex Core Detection for Computational Grid Refinement...... 38 David Kenwright

iviv C ONTENTS

Aeronautics Enterprise (continued)

Global Civil Aviation/Affordability (continued)

Wingtip Vortex Flows...... 39 Jennifer Dacles-Mariani, Dochan Kwak Transonic Overset Potential Solver ...... 40 Terry Holst Real-Time Particle Tracing in Time-Varying Flows ...... 41 David Kenwright, David Kao NASA Metacenter ...... 42 Mary Hultquist Portable Batch System ...... 43 David Tweten Developing a Cluster Computer from Workstations ...... 43 Reese L. Sorenson Planar Doppler Velocimetry Using Pulsed Lasers ...... 44 Robert L. McKenzie Pressure-Sensitive Paint and Photogrammetry for Aeroelastic Experiments ...... 45 Edward T. Schairer, Lawrence A. Hand Visualizing Wind-Tunnel Experimental Data ...... 47 Samuel P. Uselton, Glenn Deardorff, Leslie Keely, Yinsyi Hung, Arsi Vaziri Surface Tension Effects on Skin Friction Measurements ...... 48 G. Zilliac, A. Celic Fullerene Gear Design, Simulation, and Visualization ...... 49 Albert Globus

Global Civil Aviation/Environmental Compatibility

Civil Tiltrotor Noise Abatement Approaches ...... 51 William A. Decker, Rickey C. Simmons XV-15 Blade-Vortex Interaction Noise...... 52 C. W. Acree, Megan S. McCluer, Cahit Kitaplioglu Tiltrotor Aeroacoustic Model...... 53 Larry Young Predicting and Analyzing Rotorcraft Noise ...... 54 Roger C. Strawn, Rupak Biswas, Lenny Oliker Airframe Noise Measurements: Atmospheric Pressure ...... 55 W. Clifton Horne, Julie A. Hayes, Michael E. Watts, Paul H. Bent Airframe Noise Measurements: Pressures to 4.7 Atmospheres ...... 56 W. Clifton Horne, Stephen M. Jaeger, Mahendra Joshi, James R. Underbrink

v v Aeronautics Enterprise (continued)

Revolutionary Technology Leaps/Innovative Technology and Tools

X-36 Pioneers Advanced Aerodynamics and Flight Controls ...... 57 Rodney Bailey, Mark Sumich Closed-Loop Neural Control of Rotorcraft Vibration ...... 57 Sesi Kottapalli Coupled Navier–Stokes and Optimizer Analysis of a Transonic Wing ...... 58 Roxana M. Greenman, Samson Cheung, Eugene L. Tu Parallel Unstructured Mesh Adaption ...... 59 Rupak Biswas, Leonid Oliker, Roger Strawn Load Balancing Adaptive Unstructured Meshes...... 59 Rupak Biswas, Leonid Oliker, Andrew Sohn Initial Release of the Field Encapsulation Library ...... 61 Steve Bryson RANS-MP: Portable Parallel Navier–Stokes Solver...... 61 R. Van der Wijngaart, Maurice Yarrow Parallel Tools for Parallel and Distributed Computer Systems ...... 63 D. DiNucci, M. Frumkin, R. Hood, H. Jin, L. Lopez, R. Papasin, C. Schulbach, J. Yan Numerical Aerodynamic Simulation Parallel Benchmarks 2.2 ...... 65 William Saphir, R. Van der Wijngaart, Alex Woo, Maurice Yarrow Large-Scale Parallel Semiconductor Simulation ...... 65 Subhash Saini

Revolutionary Technology Leaps/Supersonic Technology

Nonlinear Aerodynamic Shape Optimization of High-Speed Research Configurations ...... 66 Susan Cliff, James Reuther, Ray Hicks Surface Operations Behavioral Evaluation Interim Testbed for High-Speed Research ...... 68 Mary K. Kaiser

Revolutionary Technology Leaps/Access to Space

Propulsion Checkout and Control System...... 69 Ann Patterson-Hine

vivi C ONTENTS

Space Science Enterprise

Overview ...... 71

Progress in Exobiology

Remote Analysis of Martian Surface Materials ...... 74 D. Blake, P. Sarrazin, D. Bish, D. Vaniman, S. Chipera, S. A. Collins, T. Elliott Stable Isotope Biogeochemistry of Hydrothermal Systems ...... 76 David J. Des Marais Fossilization Processes in Thermal Springs ...... 77 Jack Farmer, Sherry Cady, David J. Des Marais Molecular Biomarkers for Stromatolite-Building Cyanobacteria...... 78 Linda L. Jahnke, Roger E. Summons, Harold P. Klein Earth-Threatening Comets Leave Tell-Tale Dust Trails ...... 80 Peter Jenniskens, David Morrison Capturing Cosmic Dust on Mir ...... 81 Kenji Nishioka, Ted Bunch, Mark Fonda, Glenn Carle, Sherwood Chang, James Ryder, Janet Borg Simple Peptides at Water-Membrane Interfaces...... 82 Andrew Pohorille, Christophe Chipot Silicon-Micromachined Gas Chromatography System ...... 84 Thomas Shen, James Suminto, Frank Yang, Daniel Kojiro, Glenn Carle Nitrogen Sources and Sinks on Early Earth ...... 85 David P. Summers

Progress in Planetary Systems

Planetary Rings ...... 86 Jeff Cuzzi Planetesimal Formation in the Protoplanetary Nebula ...... 87 Jeff Cuzzi PASCAL: A Mars Climate Network Mission ...... 87 Robert M. Haberle, David C. Catling, Steven C. Merrihew The Center for Star Formation ...... 88 D. Hollenbach, P. Cassen Energetic Trapped Particles near Jupiter ...... 89 John D. Mihalov Wavelet Software ...... 90 Jeff Scargle Time-Dependent Structures in Galaxies ...... 90 Bruce F. Smith, Richard A. Gerber, Richard H. Miller, Thomas Y. Steiman-Cameron Galileo Encounters Jupiter: Results from the Probe ...... 91 Richard E. Young

viivii Space Science Enterprise (continued)

Progress in Planetary Systems (continued)

Regolith Effects on Mars’ Climate ...... 92 Aaron Zent The Nature of the Martian Oxidants ...... 92 Aaron Zent A Thermo-Acoustic Oxidant Sensor ...... 93 Aaron Zent

Progress in Astrophysics

Astrobiology in the Astrochemistry Laboratory ...... 93 Louis J. Allamandola, Scott Sandford, Max Bernstein, Robert Walker, Dave Deamer Spectrum Synthesis of Hot Water in Sunspots and Selected Cool Stars ...... 94 Duane F. Carbon, David Goorvitch A High-Altitude Site Survey for SOFIA...... 95 Michael R. Haas, Leonhard Pfister Kepler Mission Educational and Public Outreach Software ...... 96 David Koch Mid-Infrared Studies of Diffuse Interstellar Material ...... 97 Thomas L. Roellig Infrared Observations of G0.18-0.04 ...... 98 Janet P. Simpson, Sean W. J. Colgan, Angela S. Cotera, Edwin F. Erickson, Michael R. Haas, Mark Morris, Robert H. Rubin New 3.405-Micron Interstellar Emission from Organic Hydrocarbons ...... 99 Gregory C. Sloan, Jesse D. Bregman

Progress in Space Technologies

Assessment of the Cassini Command and Data Subsystem ...... 101 Edward A. Addy Automatic Telescope Project ...... 101 John Bresina Guide Star Tracker for Gravity Probe B Relativity Mission ...... 103 John H. Goebel Pulse-Tube Cryocooler Development ...... 103 Peter Kittel Automated Space System Experimental Testbed Project ...... 105 Christopher Kitts Amphion and Meta-Amphion...... 105 Michael Lowry

viiiviii C ONTENTS

Space Science Enterprise (continued)

Progress in Space Technologies (continued)

Focal-Plane Sensor Array Development for Astronomy in Space ...... 106 Mark E. McKelvey, Robert E. McMurray, Jr., Craig R. McCreight Intelligent Execution for Autonomous Spacecraft...... 108 Barney Pell New Millennium Program Deep Space 1 Flight Software Program Management ...... 108 Scott Sawyer

Human Exploration and Development of Space Enterprise

Overview ...... 111

Astronaut Health/Science

Biochemical Markers of Bone Metabolism in a Rat Spaceflight Model ...... 114 Meena Navidi, Jeanne Wren, Sara Arnaud Cerebrovascular Responses Prior to Fainting ...... 115 Kana Kuriyama, Toshiaki Ueno, Richard E. Ballard, Donald E. Watenpaugh, Suzanne M. Fortney, Alan R. Hargens Chronic Exposure to Hyper-G Suppresses Otolith-Spinal Reflex in the Rat ...... 116 Nancy G. Daunton, Merylee Corcoran, Robert A. Fox, Li-Chun Wu “Dual Adaptation” to Space-Related Sensory Rearrangements...... 118 Robert B. Welch

Technology Applications to Human Health

Virtual Environment Surgery Workbench ...... 119 Muriel D. Ross Noninvasive Estimation of Pulsatile Intracranial Pressure Using Ultrasound ...... 120 Toshiaki Ueno, Richard E. Ballard, John H. Cantrell, William T. Yost, Alan R. Hargens MRI-Compatible Spinal Compression Harness ...... 122 Richard E. Ballard, Donald E. Watenpaugh, Iwane Mitsui, Klaus P. Fechner, Douglas S. Schwandt, Alan R. Hargens Near-Infrared Spectroscopy to Monitor Forearm Muscle Oxygenation ...... 123 Gita Murthy, Alan R. Hargens BIONA 1—Blood Flow Ion Analyzer...... 125 John W. Hines, Christopher J. Somps Intelligent Controller for Neurosurgery ...... 126 Robert Mah

ix ix Human Exploration and Development of Space Enterprise (continued)

Technology Applications to Human Health (continued)

Center for Health Applications of Aerospace Related Technologies (CHAART) ...... 128 Byron Wood, Louisa Beck, Sheri Dister, Brad Lobitz Telemedicine Spacebridge to Russia ...... 128 Steve N. Kyramarios

Progress in Improving Space Travel

Advanced Life Support/Human Exploration and Development of Space Enterprise Activities ...... 129 Dick Lamparter, Mark Kliss Mir Hardware—Stepping Stone to Station ...... 130 Bonnie P. Dalton, James Connolly, Gary Jahns, Paul Savage Wireless Network Experiment for Space Shuttle/Mir ...... 131 Richard Alena Engine Diagnostic Filter System...... 132 Tarang Patel Formal Lightweight Approaches to Validation of Requirements Specifications ...... 133 Steve Easterbrook

Astronaut Health/Countermeasures

Autogenic-Feedback Training as a Potential Treatment for Postflight Orthostatic Intolerance ...... 135 Patricia S. Cowings, William B. Toscano Exercise for Long-Duration Spaceflight ...... 138 Donald E. Watenpaugh, Richard E. Ballard, Karen J. Hutchinson, Jaqueline M. William, Andrew C. Ertl, Suzanne M. Fortney, Lakshi Putcha, Wanda L. Boda, Stuart M. C. Lee, Alan R. Hargens Keiser SX-1 Variable Resistance Exercise Device ...... 139 Jennifer Pedley, Anthony Artino, Richard Ballard, Alan R. Hargens Dehydration at Airline Cabin Altitude ...... 141 John E. Greenleaf, Peter A. Farrell, Helmut Hinghofer-Szalkay

x x C ONTENTS

Mission to Planet Earth Enterprise

Overview ...... 145

Ecosystem Science and Technology

AIRDAS—Use of Remote Sensing for Disaster Assessment and Management ...... 147 James Brass, Vincent Ambrosia, Robert Slye Bay Area Digital Georesource ...... 147 Edwin Sheffner, Sheri Dister, Don Sullivan Brazil/United States Environmental Monitoring and Global Change Program ...... 148 James Brass, Vincent Ambrosia Carnegie/Ames/Stanford Approach Model ...... 149 Christopher Potter Digital Array Scanning Interferometer ...... 149 Steve Dunagan, Philip Hammer Effect of Landuse on Regional Estimates of Coniferous Forest Water and Carbon Budgets ...... 151 Joseph Coughlan, Jennifer Dungan Landsat Program ...... 152 Edwin Sheffner Leaf Modeling ...... 152 Lee F. Johnson, Chris Hlavka, Philip D. Hammer, David L. Peterson Mapping Northern Ecosystems: Applications for Circumpolar Methane Exchange...... 153 Vern Vanderbilt, Guillaume Perry, Joel Stearn Modern Ecosystems Research: Effects of Increased UV-B Radiation...... 153 Hector L. D’Antoni, J. W. Skiles Optimizing an Ecosystem Model for Use on Parallel/Distributed Processors...... 154 J. W. Skiles, Cathy Schulbach Paleoenvironmental Research ...... 155 Hector L. D’Antoni Scientists’ Intelligent Graphical Modeling Assistant ...... 155 Jennifer Dungan

Atmospheric Chemistry

Airborne Natural Radionuclide Measurements in the Development and Validation of Global Three-Dimensional Models ...... 156 Mark Kritz, Stefan Rosner, Robert Chatfield, Leonard Pfister Reactive Nitrogen Data from the Upper Troposphere and Lower Stratosphere ...... 156 Hanwant B. Singh, Alakh Thakur, Peter Mariani Airborne Autotracking Sunphotometry ...... 157 Philip B. Russell, John M. Livingston, James Hanratty, Damon Ried, Jill Bauman

xi xi Mission to Planet Earth Enterprise (continued)

Atmospheric Chemistry (continued)

Analysis of Stratosphere/Troposphere Exchange ...... 157 Leonhard Pfister, Henry Selkirk Use of Argus in Atmospheric Studies ...... 158 Max Loewenstein Airborne Tunable Laser Absorption Spectrometer...... 158 Max Loewenstein, James R. Podolske Convectively Generated Gravity Waves ...... 159 Leonhard Pfister The ER-2 and DC-8 Meteorological Measurement Systems ...... 159 K. Roland Chan, T. Paul Bui, Antonio A. Trias, Stuart W. Bowen, Jonathan Dean-Day Environmental Research Aircraft and Sensor Technology ...... 160 Steve Wegener Global Emissions Inventories for Radon and the Cosmogenic Radionuclides...... 161 Mark Kritz The Great African Plume: Tropical Carbon Monoxide and Ozone Simulation ...... 162 Robert B. Chatfield Instrument for Tropospheric Nitrogen Studies...... 163 James R. Podolske Reactive Nitrogen and Oxygenated Hydrocarbon Measurements during the Pacific Exploratory Mission...... 163 Hanwant B. Singh, W. Viezee, R. Chatfield, Y. Chen, D. Herlth, R. Kolye Subsonic Aircraft: Contrail and Cloud Effects Special Study...... 163 Owen B. Toon, Steve Hipskind, Duane Allen, Paul Bui, Roland Chan, Mike Craig, Guy Ferry, Steve Gaines, Warren Gore, Eric Jensen, Joe Jordan, Stefan Kinne, Bill McKie, Peter Pilewskie, Rudi Pueschel, Tony Strawa, Annette Walker Stratospheric Tracers of Atmospheric Transport ...... 164 Stephen Hipskind, Michael Craig Tropospheric Aerosol Radiative Forcing Observational Experiment ...... 165 Philip B. Russell, John M. Livingston, Wendy Whiting

Atmospheric Physics

Fine Particle Emissions by Aircraft ...... 166 Rudolf F. Pueschel, Guy V. Ferry, Anthony W. Strawa, Duane Allen FIRE Phase III ...... 166 Peter Pilewskie, Warren Gore Laboratory Spectroscopy of Carbon Dioxide in Support of Planetary Atmospheres Research ...... 167 Lawrence P. Giver, Charles Chackerian, Jr.

xiixii C ONTENTS

Mission to Planet Earth Enterprise (continued)

Atmospheric Physics (continued)

Near-Infrared Remote Sensing of Cloud Liquid Water ...... 167 Peter Pilewskie, Warren Gore Quantitative Infrared Spectroscopy of Minor Constituents of the Earth’s Atmosphere ...... 168 Charles Chackerian, Jr., Lawrence P. Giver Stratospheric Transport...... 169 Rudolf F. Pueschel, Guy V. Ferry, Anthony W. Strawa, Duane Allen SUCCESS Irradiance Measurements ...... 170 Peter Pilewskie, Warren Gore

Appendix

Color Plates (1–22) ...... 172

xiiixiii Aeronautics and Space Transportation Technology Enterprise A ERONAUTICS AND SPACE TRANSPORTATION T ECHNOLOGY ENTERPRISE

O v e r v i e w The highlighted FY96 accomplishments address the following NASA’s mission for the Aeronau- goals of the Global Civil Aviation tics and Space Transportation Tech- pillar: nology (ASTT) Enterprise is to pioneer 1. Safety goal: Reduce the aircraft the identification, verification, accident rate by a factor of 5 transfer, application, and commercial- within 10␣ years, and by a factor ization of high-payoff aeronautics and of 10 within 20 years. space transportation technologies. 2. Affordability goals: (a) While Ames’ researchers and technologists maintaining safety, triple the support this mission by seeking aviation system throughput, in enabling revolutionary technological all weather conditions, within advances that will provide air and 10␣ years and (b) reduce the cost space travel for anyone, anytime, of air travel by 25% within anywhere more safely and more 10␣ years, and by 50% within affordably, and with less effect on the 20␣ years. environment and with improved 3. Environmental compatibility goal: business opportunities and global Reduce the perceived noise levels security. of future aircraft by a factor of 2 This pursuit of revolutionary (from those of today’s subsonic technologies addresses bold, mid- aircraft) within 10␣ years, and by a term and long-term goals of the factor of 4 within 20 years. ASTT Enterprise to enable dramatic improvements in aviation and space Research and development transportation. This reflects national conducted by the ASTT Enterprise has priorities as outlined by the National been structured to be led by specified Science and Technology Council. NASA research centers according to These goals are grouped into three the primary roles and missions that areas, or as they are called, three have been assigned to each center. pillars: “Global Civil Aviation,” Ames is the lead center for the High “Revolutionary Technology Leaps,” Performance Computing and Com- and “Access to Space.” The following munications (HPCC) Program and for sections outline these goals and the research and technology (R&T) Ames’ FY96 accomplishments toward base programs in aviation operations achieving them. systems, information technology, and rotorcraft. In addition, Ames leads the Pillar 1: Global Civil Aviation Enterprise core competencies in the Today, with over 11,000 air- areas of human factors, air-traffic planes in commercial service world- management, information system wide, the United States faces strong technologies, and rotorcraft R&T. international competition in this vital Ames’ significant involvement area whose products are the largest in the safety goal includes human positive industrial contributor to the factors, information technology, and U.S. balance of trade. Projects linked condition-based maintenance. Ames to world economic growth suggest made significant contributions toward that air travel demand will triple over addressing this goal, contributions the next 20 years. Therefore, to that led to advances in aviation preserve our Nation’s economic performance measuring, aviation health and the welfare of the traveling safety reporting, crew activity track- public, NASA must provide high-risk ing, air-traffic complexity, aircraft- technology advances that will separation risk modeling, air and contribute to safer, more affordable, ground integration, and human error more environmentally compatible air in aircraft maintenance. travel. Airlines and businesses lose billions of dollars annually as a result

1 3 of delays and lost productivity owing Modification Project at Ames’ computations. Experimental aircraft to weather and congestion in the National Full-Scale Aerodynamics are also invaluable tools for exploring airspace system. Under affordability Complex (NFAC), which is currently new ideas. An example is provided goal (a) (above), Ames’ major effort being completed. In this report, with the use of advanced aero- in research and development of air- accomplishments related to helicopter dynamics and flight controls on the traffic management automation noise and airframe noise are X-36 aircraft. constitutes virtually all of NASA’s presented. Under the high-speed transport work in that area. Accomplishments goal, Ames has diverse activities in include articles on controller perfor- Pillar 2: Revolutionary Technology wind-tunnel testing and simulation, mance under simulated free-flight Leaps external visibility, sonic boom conditions, techniques for low- NASA’s charter is to explore high- minimization, and wing aerodynamic visibility taxi and ground-collision risk technology areas that can revolu- optimization. Articles are presented in avoidance, and conflict-prediction tionize air travel and create new this report to highlight these activities. algorithms. markets for U.S. industry. The tech- Reducing the costs of aircraft nology challenges for NASA include Pillar 3: Access to Space operation and maintenance is a major accelerating the application of In coming decades, NASA challenge. NASA’s test facilities and technology advances, eliminating envisions the space frontier as a busy core expertise in materials, structures, the barriers to affordable supersonic crossroads of U.S.-led international aerodynamics, propulsion, analytical travel, and expanding general science, research, commerce, and methods, and computational tools are aviation, exploration. Experience with this vast key elements in helping to revolution- The highlighted FY96 accom- resource has already yielded new ize aircraft design and manufacturing. plishments address the following two treasures of scientific knowledge, life- NASA’s research efforts are focused goals of the Revolutionary Technol- enhancing applications for use on on innovative design techniques and ogy Leaps pillar: Earth, and fantastic celestial discover- structural concepts. Ames’ contribu- 1. Provide next-generation design ies. The potential for the future seems tions to affordability goal (b) come tools and experimental aircraft to almost limitless. from rotorcraft, national tasking increase design confidence, and Ames addresses the following facilities, and research and develop- cut the aircraft development goal of the third pillar, Access to ment of computational tools. Several cycle time in half. Space: Ames projects contributed to rotor- 2. Reduce the travel time to the Far 1. Reduce the payload cost to craft research and technology East and Europe by 50% within low-Earth orbit by an order of activities, which include rotor aero- 20 years, and do so at today’s magnitude, from $10,000 to dynamics, testing of new concepts, subsonic ticket prices. $1,000 per pound, within stall control, in-flight dynamic stall 10␣ years. The next-generation design tools research, and vortex flows. Examples and experimental aircraft goal will As NASA’s lead center for of accomplishments that enhance dramatically affect the way in which thermal protection systems (TPSs) computational tools are vortex-core business is conducted. Its effect will technology, Ames is charged with detection and tracking of particles in be felt across the three pillars, contrib- developing new thermal protection time-varying flows. Improvements in uting to every technology goal. Ames systems that will enable vehicles the use of facilities are highlighted in has significant work in integrated of the future to be built more eco- the following pages by articles on design systems and the X-36 aircraft. nomically and that will enable planar Doppler velocimetry, pressure- Research is done at Ames in informa- existing ones to be upgraded at sensitive paint and photogrammetry, tion technology to elevate the power reduced cost. Ames maintains one of and visualization of experimental of computing tools through fuzzy the world’s premier arc-jet complexes data. A high-risk, long-term research logic, neural networks, and artificial for providing realistic simulations of effort directed to the manufacture of intelligence. These tools will integrate entry environments. These simulations fullerene nanotechnology gears is also multidisciplinary product develop- are essential for technology develop- described. ment activities to dramatically cut ment, system validation, and system For research related to the design cycle times. Examples of qualifications. Ames supports the U.S. environmental compatibility goal, accomplishments include neural aerospace community in developing Ames has significant aeroacoustic control of rotorcraft vibration, cou- TPSs that will be necessary for the research and testing capabilities, the pling of flow-field computation tools nation’s future space vehicles. most recent advance in those capa- with design optimization tools, and bilities being the Aeroacoustic parallel computational tools and

4 2 A ERONAUTICS AND SPACE TRANSPORTATION T ECHNOLOGY ENTERPRISE

G GLOBALLOBAL C CIVILIVIL A AVIATIONVIATION/S/SAFETYAFETY cessed automatically in order to Visual Basic. The client-server address questions relating to opera- database architecture and method tional performance and safety. for the initial build have been Aviation Performance The Aviation Performance selected. Teledyne Control’s Measuring System Measuring System (APMS) is provid- FLIDRAS software has been acquired Irving C. Statler ing technical tools to facilitate the to read Flight Data Recorder raw large-scale implementation of flight- data parameters, to convert the data Flight Operations Quality data analyses at both the air-carrier into engineering units, and to Assurance (FOQA) programs using and the national-airspace levels. perform data dumps into the data- flight-recorded data have been APMS enhances the existing base management system. As the providing critical safety information Commercial Off The Shelf (COTS) flight database is built, the baselines to non-U.S. airlines for over two capabilities of FOQA, including the of various routine operations will be decades. Although the benefits of capability of analyzing all the data established. Knowledge-based tools, these programs have been demon- collected, in addition to merely currently under development by the strated, the U.S. air carriers have identifying “exceedances” or APMS team, will, in later iterations found them impractical to imple- “special events” (the figure shows when an adequate database is ment because of the extensive the APMS functions). available, provide statistical trending labor required to process the great Phase 1 of the APMS effort and predictive capabilities. The first amounts of data that would typically ended in December 1995. Phase 2 prototype system was delivered in be generated. A collaborative effort focuses on three tasks: (1) selection July 1996 to the first airline partner. was initiated in August 1993 and implementation of an APMS The prototype system is now opera- between the Federal Aviation client-server database architecture; tional and currently being used to Administration (FAA) and NASA to (2) development of a knowledge- process airline flight data. establish and demonstrate the based system for verifying and With the industry becoming feasibility of developing a set of diagnosing “special events” flagged aware of the capabilities of the tools that would allow very large by COTS packages; and (3) construc- APMS suite of tools, the team is quantities of flight data to be pro- tion of a friendly user-interface in being approached by other airlines that had not been solicited to participate in the research project.

Screening for Statistical So far, one additional major airline Flight data special events analysis and one major cargo airline have 90 inputs 80 70 asked to participate in the program. 60 50 40 User-needs studies have been 30 20 10 completed with four U.S. airlines 0 1995 1996 1997 1998 1999 2000 and a fifth has been started. Agree- ments have been signed with two Database of these to cooperatively develop customized suites of APMS tools. The APMS effort continues to work with collaborators to improve system design.

Point of Contact: I. Statler Database Database Flight linkage (650) 604-6655 animation exploration [email protected]

Fig. 1. APMS functions.

G LOBAL CIVIL AVIATION / Safety 3 Aviation Safety Reporting System Incident reports Linda J. Connell Safety alerts The Aviation Safety Reporting Quick responses System (ASRS) solicits, processes, to FAA & NTSB and analyzes aviation safety incident reports from pilots, air-traffic control- ASRS lers and others and uses the data it collects to further aviation safety. Database Database The ASRS (1) codifies the reports it search CD ROM receives (31,096 in FY96) and inserts requests them into a computer database; 90 80 70 60 (2)␣ issues alerting messages on 50 40 30 20 10 pressing safety problems described 0 1995 1996 1997 1998 1999 2000 by incoming reports; (3) provides data retrieval services (search Monthly safety Quarterly safety Research requests) for aviation safety research- newsletter bulletin ers and others; (4) publishes a monthly safety bulletin, CALLBACK, Fig. 1. ASRS products. and a periodic safety journal, DIRECTLINE; (5) performs Quick Response analytic efforts for the ␣ ␣ •␣ ␣ Accomplished a Multi-Engine ␣ ␣ •␣ ␣ Accomplished the second Federal Aviation Administration Turbojet Uncommanded Upsets installment of the Wake Turbu- (FAA), the National Transportation Structured Callback Analysis for lence Structured Callback Safety Board (NTSB), and other the NTSB. The analysis was Project Reports; it included the governmental entities; and (6) does subsequently adopted into the analysis of 51 wake turbulence applied research on aviation opera- USAir B-737 accident investiga- incidents and was submitted to tional problems, especially those tion report. the FAA. involving human performance (see ␣ ␣ •␣ ␣ Completed a GPS Safety Impact ␣ ␣ •␣ ␣ Produced search requests for the the figure). The ASRS is heavily Analysis for the FAA Associate NTSB and the FAA on DC-9 reliant on information technology, Administrator of Research and cabin/cockpit smoke and aircraft and a portion of program resources Acquisitions. equipment problems in support is devoted to maintaining and ␣ ␣ •␣ ␣ Accomplished a Quick Response of the investigation of the DC-9 upgrading that technology. analysis of Runway Transgres- accident near Miami, Florida, on The following list is a summary sion Data for the FAA Office of May 11, 1996. of some of ASRS’s FY96 activities. In System Safety. These data were ␣ ␣ •␣ ␣ Produced a Quick Response FY96, the ASRS program: subsequently presented to the analysis of Part 135 Aircraft ␣ ␣ •␣ ␣ Initiated an ASRS Internet site in FAA deputy administrator. Incidents for the Australian November 1995. Through its ␣ ␣ •␣ ␣ Completed Quick Response Bureau of Air Safety Investiga- Web site, ASRS offers its publi- No.␣ 289 entitled “Near Mid-Air tion. The data are being used to cations, program information, Collision Data Analysis” for the develop a proactive aviation and downloadable (using an FAA Office of System Safety. safety hazard monitoring system. Adobe Acrobat reader) versions of the NASA Incident Reporting Forms.

4 G LOBAL CIVIL AVIATION / Safety A ERONAUTICS AND SPACE TRANSPORTATION T ECHNOLOGY ENTERPRISE

␣ ␣ •␣ ␣ Transmitted 30 runway- ␣ ␣ •␣ ␣ Completed a conceptual and unexpected behavior. One remedy incursion reports at Cleveland- editorial review for a second is to develop technology that can Hopkins Airport, Ohio, to the NASA project, a study on the detect potential operator errors and FAA Office of System Safety and use of modes in human-machine provide the operator with context- the Air Line Pilots Association. interactions. This study, which sensitive advice and reminders. To As a result of ALPA and FAA was completed, made use of be effective, such technology must follow-up actions, revised ASRS data. incorporate knowledge about ground-control procedures were operator-automation interaction in Point of Contact: L. Connell implemented for departures context; for flight deck application, (650) 604-6654 using runways 23L/23R. this includes knowledge about mode [email protected] ␣ ␣ •␣ ␣ Transmitted 24 reports to FAA management. and ALPA involving altitude This research addresses an deviations at FUELR Intersection enabling technology called activity on the CIVET ONE ARRIVAL to tracking, a way of inferring intent. As Los Angeles International Crew Activity Tracking the name implies, the Crew Activity Airport. Subsequent investiga- System Tracking System (CATS) is an tion by the FAA determined that architecture that implements a the recent installation of a new Todd J. Callantine method for activity tracking (see the ILS had changed the glidepath first figure). CATS represents knowl- Human operators supervising angle at FUELR. edge about the operator’s tasks using ␣ •␣ ␣ Published one issue of advanced automation systems can an explicit, task-analytic model have difficulties that have the DIRECTLINE in FY96. Its based on the goal-based decomposi- potential to compromise safety. For research articles addressed tion of tasks into subgoals and aircraft call-sign confusion and example, a recent study found that primitive tasks. CATS uses the model over 44% of flight deck problems ramp safety. to predict operator intentions and to cited in a large body of incident and ␣ ␣ •␣ ␣ Developed a trial version of the interpret subsequent operator ASRS Intranet communications accident reports were related to actions. The predictions and inter- automation. Autoflight system system. It runs on an NT Server pretations are designed to supply the modes, in particular, are often and is available to the ASRS knowledge required for intelligent staff. The decision was made in implicated because they can cause aiding and training systems. January 1996 to develop this internal Intranet communications system based on existing Constraints on Internet applications in order to operation lower costs and increase effi- CATS ciency internally at the ASRS. Crew activity model ␣ ␣ •␣ ␣ Commenced a collaborative State Context information specifiers research project between OFM- NASA and its French counter- Constraints ACM on operation part, ONERA, to evaluate an Predictions ONERA human factors coding Human scheme and taxonomy for Controlled operators system Crew Action Interpretations possible application to ASRS actions manager incident data. [to aid or training system]

Fig. 1. The Crew Activity Tracking System in context.

G LOBAL CIVIL AVIATION / Safety 5 assigned descent point or signals a access-LEGS-pg push-LEGS-key potential error. A Boeing 747-400 simulator build-ctas-adp-ref-wpt put-ref-wpt-scr-pad study to investigate pilot perfor- enter-ctas-adp-ref-wpt put-ref-wpt-LEGS-pg mance on a new descent procedure was conducted at Ames Research program-ctas-adp build-ctas-adp-ref-dist put-ref-dist-scr-pad Center. The data show that although enter-ctas-adp-ref-dist put-ref-dist-LEGS-pg pilots performed the new procedure effectively in most cases, there were verify-ctas-adp SOP-talk still a number of compliance viola-

execute-ctas-adp push-EXEC-key tions. These data are used to investigate a new application of CATS: tracking crew activities to automati- Fig. 2. A simplified task decomposition from the enhanced CATS model. cally identify departures from the procedure and capture the context in which these departures occurred. With this information, the procedure CATS was implemented to track are being developed for use with may be refined to address problems, the activities of Boeing 757 pilots new air-traffic control automation. and thereby improve compliance. using autopilot flight modes under The second figure shows a normal operating conditions. An simplified task decomposition from Point of Contact: T. Callantine experimental evaluation was con- the enhanced CATS model, from (650) 604-2631 ducted to assess the effectiveness of which most cognitive, verbal, and [email protected] the CATS method. Ten type-rated perceptual activities are omitted. The line pilots from a major airline task shown supports a new descent participated in the study. Each flew procedure that uses an assigned five experimental scenarios on a descent point (“adp”), in addition to real-time part-task simulation of the the top-of-descent point computed Study of Line Oriented Boeing 757. Of the 2,089 pilot by the FMC. When the crew has Flight Training actions detected in the study, CATS been cleared for the procedure, Key R. Dismukes correctly interpreted 81%. A subse- CATS uses this portion of the model quent analysis identified adjustments to predict and interpret the CDU Airlines train pilots to work to the CATS model and processing programming activities required to together as safe, efficient crews by scheme that would allow CATS to perform the task. For example, CATS using a realistic full-mission flight correctly interpret 94% of pilot first predicts which pilot is respon- simulation approach called Line actions. sible for programming the assigned Oriented Flight Training (LOFT). In Current research seeks to extend descent point to go to the CDU this annual recurrent training, crews the capabilities of CATS and to LEGS page. CATS next predicts that encounter challenging situations that explore new applications. Specifi- a reference way point will be built in they must manage by coordinating cally, the objective is to enable the CDU scratchpad, then line- their efforts, exercising good judg- CATS to predict and interpret the selected to the appropriate place on ment and decision-making, and actions of two-person crews by using the LEGS page, and so on. As these drawing upon all available complex functions of the Flight actions are performed, CATS checks resources. After the LOFT, the Management Computer Control and the entered values for accuracy and instructor leads the crew in a Display Unit (FMC CDU), and data- then either interprets the actions to debriefing in which they are link communications. These activi- support the task of entering the expected to analyze what happened, ties are critical for procedures that evaluate their own performance,

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and identify ways to improve and when to use these techniques, would be a function of the complex- performance. Because the LOFT is a and shows how to engage crews that ity of the airspace. very busy, intense experience, how do not initially respond. Immediately Shifts in operational procedures much the crews learn from the LOFT after receiving the study materials, will be specified as a function of and take back to line operations several major airlines reprinted the airspace complexity, making the hinges on the effectiveness of the manual for the use of their instruc- development of separation proce- debriefing. tors. Other airlines have overhauled dures dependent on the develop- Both the airlines and the FAA their training of instructors to ment of a complexity metric. The espouse the idea that LOFT instruc- incorporate the findings from the complexity of air-traffic patterns, and tors should refrain from lecturing the study; they later reported significant hence the workload related to the crews in the traditional “teacher-tell” benefits to their crew training management of air traffic, is known manner. Instead, instructors are programs. to include more than a simple count encouraged to “facilitate” self- of aircraft contained in a volume of Point of Contact: K. Dismukes analysis by the crew so that they will airspace. However, the traffic (650) 604-0150 learn more deeply. However, there complexity factors beyond that of [email protected] has been little study of how to aircraft number have not been facilitate this self-analysis; as a clearly identified, nor has any consequence, the airlines have not relationship among the factors been had good data-based techniques for established. training their instructors in debriefing Measuring Air Traffic A human-in-the-loop simulation procedures. Complexity study was conducted to evaluate Human factors scientists at three modes of separation responsi- Ames recently completed a study, Irene V. Laudeman, Connie Brasil, bility and to provide data for use in in collaboration with major U.S. Robert Branstrom developing a complexity metric. Ten airlines, to evaluate LOFT debrief- groups of four currently qualified air- An important goal in advanced ings and to provide guidelines for traffic controllers participated in nine training instructors. The study air-traffic operations is that of simulation scenarios. In each group providing more system flexibility to evaluated the effectiveness of LOFT one participant acted as the control- the user. The idea of sharing the debriefings at a cross section of ler in a sector of airspace and three airlines, analyzed facilitation responsibility for aircraft separation, participants acted as pilots. in which pilots and air-traffic techniques, and identified common Aircraft data in the form of controllers work together to ensure errors. The study demonstrated that latitude, longitude, heading, altitude, instructors who are effective in separation, is designed to provide and speed were collected for all of such flexibility. Currently, under facilitating self-analysis substantially the aircraft in each of the nine instrument flight rules the air-traffic increase the depth of crew participa- 30-minute scenarios. The complexity tion and self-analysis; however, controller is tasked with ensuring the of the simulated airspace was proper separation of aircraft. Under individual instructors differed greatly computed from the aircraft data at shared separation-responsibility in their effectiveness as facilitators. every 2 minutes of the 30-minute In conjunction with the techni- procedures, pilots in appropriately scenarios. Complexity functions equipped aircraft would assume cal report of the study, the research were computed as a sum of traffic some responsibility for the manage- team prepared a detailed manual for factors that included aircraft count, use in training instructors to facilitate ment of aircraft separation. The aircraft converging at the same proportion of responsibility assigned debriefings. This manual explains altitude, and aircraft changing to pilots and air-traffic controllers the concepts of facilitation, describes heading, speed, or altitude. effective techniques, explains how

G LOBAL CIVIL AVIATION / Safety 7 Although industry initiatives involv- Shift in separation responsibility ing human factors training in 140 Scenario 1 shift maintenance have become increas- Scenario 1 shared (3) ingly accepted as one type of 120 Scenario 2 shift maintenance error intervention, Scenario 2 shared (7) there remains a dual challenge: 100 (1)␣ to develop human factors interventions that are directly supported 80 by reliable human error data, and (2)␣ to integrate human factors 60 concepts into the procedures and Dynamic density 40 practices of everyday technical tasks. These challenges are being 20 addressed at Ames Research Center. First, industry-wide incidents 0 reported to the Aviation Safety 2 4 6 8 10121416 18 20 22 24 26 Reporting System are being analyzed Time (min) in order to identify and characterize high priority problem areas. When Fig. 1. Air-traffic complexity functions and points at which separation analyzed for contributing factors, at responsibility was shifted for two types of traffic scenarios. least 50% of the incidents involved more than one technician—other maintenance personnel, flight crew The complexity functions Operational Interventions members, and airport personnel. predicted an operational shift related Consistent with these findings, to the sharing of separation responsi- to Human Error in Aircraft research is being conducted that bility (see the figure) indicating that Maintenance focuses on human factors interventions related to practices and such functions might be useful in Barbara G. Kanki, Vicki Dulchinos specifying shared separation respon- procedures; namely, structured on-the-job training and procedure sibility procedures. A significant proportion of re-design. In both areas, particular aviation accidents and incidents are Point of Contact: I. Laudeman attention is being centered on areas known to be tied to human error. (650) 604-0018 in which maintenance tasks require However, research of flight opera- [email protected] coordination both within and tional errors has shown that between maintenance teams. so-called “pilot error” often involves In the area of structured on-the- a variety of human factors issues job training, field applications of and not a simple lack of individual the Task Analytic Training System— technical skills. In aircraft mainte- a performance-based system that nance operations, there is similar involves full workforce participation concern that maintenance errors in its design, development, and which may lead to incidents and implementation—have been accidents are related to a large conducted. variety of human factors problems.

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free exchange of human factors A. 5% information between aircraft and B. 8% shuttle maintenance operations. X. 19% Point of Contact: B. Kanki (650) 604-5785 C. 12% [email protected]

D. 4% Aircraft Separation Risk Model F. 33% Mary M. Connors E. 19% Increased demand for air travel A. Situation awareness/Time task management (n=38) translates into a need to accommo- B. Planning/Communication-new resources (n=62) date more aircraft in the terminal C. Planning/Communication of task sequence (n=85) airspace. Separations between aircraft pairs must be small enough D. Clarification/Formatting - Simplified English (n=28) to be efficient while remaining E. Clarification/Formatting consistency (n=139) sufficiently large to be safe. Present F. Process improvement (n=243) separation standards are considered X. No functional change (n=140) safe for the equipment and conditions that presently prevail. It is Fig. 1. Distribution of reason codes in the revised procedure possible that new technologies could (N = 735 procedural steps). result in maintaining the present safety level while permitting the distances between aircraft pairs to be reduced. What is needed is a Human factors principles may results of this item-by-item compari- quantitative method of evaluating also be incorporated into the son are found in the summary of safety. The objective of this research maintenance procedures themselves. functional changes shown in the is to develop a computer model that When Boeing modified its B-737 figure. will provide this link between CFM56-7 engine-change procedure, Finally, a collaborative relation- aircraft separation and a quantitative the efficiency of the engine-change ship has been established with the method of assessing safety risk. process was significantly improved. human factors team at Kennedy The model, called the Reduced A 14% increase in efficiency, Space Center; a series of workshops Aircraft Separation Risk Assessment attributed to changes in the mainte- for discussing human factors issues Model (RASRAM), evaluates safety nance manual alone, presented an in aviation and space vehicle risks for a variety of flight scenarios opportunity to conduct a systematic maintenance is being conducted. relating to final approach, landing, comparison between original and The first workshop was held at Ames and rollout for parallel and single revised procedures. The goal was to Research Center in September 1966; runways. The basic approach of analyze the specific modifications it focused on error analysis (inci- RASRAM is to quantify the risk that led to the improvement in dents, accidents, mishaps, and close- associated with current separation efficiency and to identify the contri- calls). This workshop facilitated the standards and to then compare it bution of human factors. Some with that for reduced separation

G LOBAL CIVIL AVIATION / Safety 9 quantifying the safety risk associated MD = miss distance with the effects of these technologies on separation standards. The model Evader aircraft Blunder path can also be used to provide a relative comparison of the safety of proposed new procedures with the MD Blunder aircraft safety of current operations and Runway separation technologies. Using RASRAM, the No transgression zone safety of further separation reduc- 3° Glide path tions for parallel approaches that rely on new technologies can be analyzed and compared with current Fig. 1. Parallel approach lateral separation geometry. procedures. Similarly, the safety of reductions of in-trail separation can operations during instrument is determined (1) by the performance be compared with current proce- meteorological conditions, consider- of the controller in detecting the dures. Although it is being devel- ing procedural and technological blunder and issuing breakout oped for initial application to final changes. The research is being instructions to the evader aircraft, approach and landing, the basic performed for Ames Research Center and (2) by the performance of the approach to modeling separation as an integral part of NASA’s Termi- pilot and aircraft in completing the risk has direct application to all nal Area Productivity (TAP) program, evasive maneuver. RASRAM models phases of flight. The potential and in coordination with the Federal all of these effects and quantifies the application of these models to en Aviation Administration. safety of the operation. The standard route and approach airspace is being RASRAM includes the following risk measure is the probability that undertaken in the Advanced Air two scenarios that measure the effect the blundering aircraft will approach Transportation Technology program of separation on safety: lateral within 500 feet of an aircraft in the at Ames. separation for parallel approaches; other approach stream. Point of Contact: M. Connors and in-trail separation during single NASA’s TAP Program anticipates (650) 604-6114 runway operations, accounting for procedural changes for terminal-area [email protected] runway occupancy and wake vortex operations along with the introduc- effects. The figure illustrates the tion of new technologies. These new parallel approach scenario, for technologies include Differential which independent approaches to GPS (DGPS), Automatic Dependent parallel runways constitute the Surveillance (ADS-B), and several operational context. The primary technologies under development by separation criterion is the distance the NASA TAP program: the Center- between the runway centerlines for TRACON Automation System the two approach paths. The defin- (CTAS), the Aircraft Vortex Spacing ing characteristic of the scenario in System (AVOSS), the Dynamic the model is a blundering aircraft Runway Occupancy Measurement that strays from its own final (DROM), and the Airborne Informa- approach, crossing the path of the tion for Lateral Spacing (AILS). other approach stream. The safety of RASRAM begins the process of the scenario (for current operations)

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The Final Approach the FAST system at Ames and at the to that of the Passive FAST before a FAA Technical Center, and a limited national deployment system is Spacing Tool operational assessment of the specified. Tom Davis FAST system functionalities at Point of Contact: T. Davis Dallas/Fort Worth. (650) 604-5438 The Center/TRACON Automa- Development and field testing of [email protected] tion System (CTAS) is an air-traffic the FAST system achieved a signifi- control automation system under cant milestone during FY96; the development at Ames Research “Passive” FAST functionality, which Center. The system is designed to includes the sequence and runway support increasing demands for advisories, underwent operational Air/Ground Integration capacity and efficiency in the testing at the Dallas/Fort Worth R. Slattery National Airspace System. The TRACON. The tests, which were terminal-area component of the conducted in cooperation with the The Center/TRACON Automa- system, the Final Approach Spacing FAA, the National Air Traffic Con- tion System (CTAS) was developed Tool (FAST), is designed to assist trollers Association, and the Airline for use in the air traffic-control terminal air-traffic controllers in Transport Association, began in environment. As part of the Terminal efficiently managing and controlling January 1996 and continued through Area Productivity Air Traffic Man- arrival air traffic for the last 40 miles July 1996. The objectives of the test agement program, research has of flight down to the runway. The were: (1) to confirm the technical begun to expand CTAS to coordinate FAST system issues the controllers performance of the Passive FAST with aircraft that are equipped with a series of sequencing, runway, functionalities, (2) to assess the Flight Management Systems (FMSs) heading, and speed advisories to airport delay and capacity benefits using data-link. A large portion of achieve an efficient flow of traffic of Passive FAST, and (3) to assess the commercial aircraft fleet is so that increases airport capacity, the controller workload benefits of equipped and many older aircraft reduces delays, and reduces control- Passive FAST. The testing demon- are being retrofitted with an FMS. ler workloads. strated an arrival rate improvement However, busy air-traffic controllers The objective of the research at Dallas/Fort Worth of 13%, a do not often allow pilots to fully and development effort is to test the departure queue backlog reduction utilize the FMS. An FMS calculates FAST system operationally in a series of 9%, and an overall increase in the most efficient trajectory, thus of phased functionality enhance- total airport operations (arrivals and saving fuel, and then follows the ments at the Dallas/Fort Worth departures) of 13%, all with no trajectory very accurately, increasing TRACON (Terminal Radar Approach increase in taxi times and with trajectory prediction accuracy. Thus, Control) (see figure (see Color little or no increase in controller if the CTAS helps the controllers take Plate␣ 1 in the Appendix)). The workload. The system has received advantage of the FMS trajectory, the operational field testing of the FAST overwhelmingly positive support performance of the airspace system system allows researchers to further from all participants. should be improved. develop and assess the system with The Active FAST system The objectives of the research the end-users, that is, with the air- functionalities, including speed and and development effort are to traffic controllers. The assessments heading advisories, remain to be quantify the actual benefits of the include a series of observations with developed and operationally evalu- air/ground system with both control- the FAST system operating in a ated. The Active FAST system will lers and pilots in the loop. Theoreti- shadow mode on live traffic data, undergo operational testing similar cal benefits have been studied, real-time simulation evaluations of under the assumption that the trajectories are followed with the

G LOBAL CIVIL AVIATION / Safety 11 maximum accuracy possible for the eastern arrival gates into the trajectory while in the busy terminal FMS. These benefits may be dimin- TRACON (Terminal Radar Approach area. There were also more errors in ished, however, by the extra Control) and finishing at the runway. loading and in following the FMS workload imposed on the controllers The accuracy of the horizontal route route, though these should be and pilots; also, they may not be increased for the FMS cases, but the reduced by data-link and by inter- realizable because of operator error. vertical predictability was lower. face changes to the FMS. A piloted simulation was This was because the vertical portion Point of Contact: R. Slattery performed using the CVSRF 747-400 of the FMS route is entered as (650) 604-5435 simulator. Since the simulator was crossing altitudes at way points. As [email protected] not equipped with data-link at the long as the pilots meet the required time, the routes were defined as altitude, the point at which they stored arrivals in the FMS (an begin their descent and the way in example is shown in the figure). which they make the descent are The pilots were issued FMS route open. Offsetting the achievable The Traffic Management changes, while still performing the accuracy, the pilots felt that the FMS Advisor rest of their normal duties. For a route changes produced far more baseline comparison, equivalent workload with current generation Harry N. Swenson routes were flown using current FMS systems than did current The growth of commercial air controller clearances. The aircraft procedures. They also expressed travel within the United States has was flown in the Dallas/Fort Worth concerns about the amount of terminal area, starting at the two heads-down time spent loading the put a severe strain on the nation’s air traffic capacity. This, coupled with the “hub-and-spoke” procedures used by the major air carriers and KINGG the marketing requirements for REFLE2: Cross at 210K aircraft to take off and land at IAS. Cross at 4,000' REFLE2 NOVEL optimum times, has required an improvement in the Air Traffic Control System. The Center- TRACON Automation System (CTAS) 17LGT REFLE1 SWIFT REFLE1: Cross at 210K is a decision-support concept being IAS. Cross at 4,000' developed to improve airport JIFFY capacity and to reduce delays while Cross at 170K IAS maintaining controller workload at a reasonable level. The extended terminal-area component of the SEAGO system is the Traffic Management Cross at 250K IAS. REFIL Cross at 11,000' Advisor (TMA). The TMA is a time- Cross at 210K IAS. based strategic planning tool that Cross at 11,000' provides traffic management coordi- nators and en␣ route air traffic SCY controllers the ability to efficiently optimize the capacity of a demand- Fig. 1. Scurry FMS arrivals, REFLE1 and REFLE2. impacted airport. The TMA consists of trajectory prediction, constraint- based runway scheduling, traffic

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flow visualization, and controller tions were conducted. Subsequently, queues are evidence that although arrival sequence, time, and delay the formal operational evaluations sufficient and safe, the controller’s advisories. were conducted. The TMA mental planning process (given The TMA and all other CTAS demonstrated delay reductions of current data sources) is not necessar- tools are being developed to demon- 1–2 minutes per aircraft, as well as ily optimal. By providing data fusion strate user benefits both to air-traffic a significant reduction in controller and automated optimal taxi plan controllers and commercial air workload. The original plan was to advisories to the ground controller, carriers. Air-traffic control is a very remove the TMA upon completion the controller can operate with complex multivariable problem of the formal evaluation, but, based improved data-gathering and requiring teams of highly skilled on the benefits achieved, the FAA, planning capabilities. Improved individuals to safely and efficiently the Air Transport Association, and dynamic taxi routing, and hence move traffic from terminal departure NATCA requested that NASA smoother airport operations with point to terminal arrival. This operationally support the TMA on a less surface taxi delay should result. extended complexity requires that continuous basis. NASA has com- Eventual national implementation automation aids designed to assist plied with that request, and the TMA of the Surface Movement Advisor these teams be proven and validated has been used operationally since systems (SMA) at the 13 largest U.S. in actual operations. The objective the completion of the formal evalua- airports is projected to save users at of the TMA 1996 research and tions. Since the evaluations, a 10% least 5% of the $1.6 billion annual development effort was focused capacity increase has been attributed ground-delay costs incurred as a toward an operational evaluation to TMA operations. result of inefficient taxi and runway at the Ft. Worth Air Route Traffic queuing—based on recent FAA Point of Contact: H. Swenson Control Center, Ft. Worth, Texas. simulations and Air Transport (650) 604-5469 The evaluations also focus research Association cost figures. [email protected] into areas and concepts that provide The SMA is a series of succes- user benefits. sive airfield data systems that is The TMA achieved several being developed as a joint effort major milestones in this focused between Ames Research Center and effort toward operational evalua- Surface Movement the Federal Aviation Administration tions. The first was controller and Advisor (FAA). The first proof-of-concept operational hardware in-the-loop SMA (Build-1) electronically con- simulations at the William J. Hughes Brian J. Glass nects the air-traffic control, airline, FAA Technical Center with the and airport operations users at Recurrent delays during depar- National Air Traffic Controllers Atlanta-Hartsfield airport (ATL) to ture taxiing at large airports have Association (NATCA) Ft. Worth facilitate information-sharing and Center System Design Team. This become commonplace with the data fusion. SMA Build-1 has been prevalence of “hub-and-spoke” was followed by the installation and in use on a daily basis at ATL by airline operations, as large numbers checkout of the TMA hardware/ airlines and airport ramp towers software components at the of aircraft attempt to land, taxi, be since June 1996 and was brought serviced, taxi, and depart, all within Ft. Worth Center, the nation’s fifth online in the FAA control tower 60–90 minute “banks.” Airfield busiest Center, which manages and in September 1996. The figure controls traffic into the second tower controllers strive to avoid shows an overview of the SMA imbalances and bottlenecks by busiest airport in the world (Dallas/ system that was deployed to Atlanta integrating data from visual cues Ft. Worth). Upon completion of the in 1996. system installations, on-site shadow and from a variety of other sources. However, lengthy, imbalanced taxi evaluations and nighttime simula-

G LOBAL CIVIL AVIATION / Safety 13 ValuJet Lockheed Other airlines

FAA tower Delta Real-time Airlines Highspeed radar data network backbone SMA server Weather data

City of Atlanta airport authority Output Input Real-time aircraft manager manager status updates

Monitoring and predictions Airline schedules Flight plans

Performance Prediction Airport operations Statistical histograms algorithms procedures analysis

Fig. 1. Overview of the SMA system deployed to Atlanta in 1996.

Running in a commercial Simplified Vision Models of human observers to make such transaction-processing database on discriminations and have been an off-the-shelf UNIX server, the for Display Quality constructing and testing computa- SMA software currently contains its Assessment tional models to predict their own tracking, time estimation, data Al Ahumada abilities. fusion, monitoring and prediction Image discrimination models software modules. SMA furnishes Detection and recognition of that have been used as image-quality data as an ASCII text stream to obstacles (aircraft, trucks, etc.) is metrics range in complexity from airline servers, or as separate crucial for safe aviation operation in single filter models to multiple- X/Motif-based touchscreen-capable the terminal area. Vision models can channel models with channels that graphical-user interfaces for the FAA, make an important contribution to are selective in spatial frequency and airline, and airport operations display design by allowing computa- orientation. The simple filter models personnel. tional predictions of the visual can be thought of as representing the adequacy of potential designs for visual information at precortical Point of Contact: B. Glass obstacle detection and recognition. levels of the visual system. These (650) 604-3512 The first figure shows a pair of models can predict the variations in [email protected] simulated display images, one the visibility of targets that occur as (panel b) with an obstacle on the the target spatial frequency changes. runway and one without. Investiga- The multiple-channel models tors have been measuring the ability

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simulate the orientation and spatial applying this correction to a frequency selectivity of cortical cells. contrast-sensitivity filter model. In Because the channel outputs are comparing the predictions of this nonlinear, the channel models model with those of the complex predict masking of targets in high- models, it is found that the simple contrast image regions. For example, model predicts human visual the channel models outperform detection performance just as well. contrast-sensitivity filter models in (a) Point of Contact: A. Ahumada predicting the detectability of targets (650) 604-6257 in a natural background. [email protected] Some recent vision models include between-channel interactions that allow the models to predict masking from image components exciting different channels Perceptually Tuned Visual (b) from those responding to the target. Simulation These models have even greater Mary K. Kaiser Fig. 1. Panel (a) is a 128 x 128 pixel computational complexity. Assum- ing homogeneity of these interac- gray-scale digital image of a Human factors engineering is simulated airport runway scene. tions leads to a simple contrast masking correction. The second required to improve the quality of Panel (b) shows the runway scene visual displays in aerospace systems. figure diagrams the image discrimi- with an aircraft obstacle. Advanced computer-generated nation model that results from imagery (CGI) systems are used to create compelling visual displays for navigation/control systems, vehicle/ system simulation, telerobotics, and Background RMS Masking scientific visualization applications. n CSF 1 The quality of these displays can Σ f 2 c 2 n i 1+( ) affect the safety and productivity of C= 1 c flight and ground-based operations. Inevitably, the realism of these Target + X Euclidean displays is constrained by limitations Background X d' distance in CGI hardware and software, CSF n Σ 2 especially if images need to be di 1 generated in real-time. Despite rapid advances in image-generation technology, human operators desire Fig. 2. Schematic of the simple image discrimination model. At the left, the more realistic, higher-fidelity upper image is the background image and the lower image is the target-plus- displays; it is likely that this demand background image. After the luminance images are converted to contrast for improved fidelity will continue images (a step not illustrated), the contrast images are filtered by a contrast for the foreseeable future. sensitivity function (CSF). On the top path, the masking parameter c is the Research is being conducted rms value of the background-filtered contrast values fi. On the bottom path, to examine techniques aimed at the corresponding filtered values from the image are differenced and the reducing the computational cost vector length of these di values is divided by the contrast factor to get the required to achieve a desired level of predicted number of just-noticeable-differences between the two images. image quality and frame rate. These

G LOBAL CIVIL AVIATION / Safety 15 techniques exploit principles of A set of techniques has been demonstrates varying polygonal visual processing to reduce the developed for rendering images with complexity. The resulting fused computational load. This multi- enhanced apparent resolution. image appears to possess the higher- disciplinary research involves a NASA has applied for a patent for resolution detail. User studies collaboration among research this process (NASA Case: ARC conducted with these “hi-lo” stereo scientists at the Ames Research 12080-1). In using this process to displays indicate that people are Center; professors in computer create stereo displays, images with able to extract stereo-specified depth science at Carnegie Mellon Univer- different resolutions are shown to the with these displays about as well as sity and in psychology/biomedical two eyes; examples of this technique they do with traditional (“hi-hi”) engineering at the University of are shown in the figures below. The displays. Further, no interference Virginia; and designers and engi- first figure demonstrates varying with normal stereo vision results neers at various industry sites. texture complexity; the second from exposure to the hi-lo displays. Present efforts focus on further evaluation of the algorithms, the extension of techniques to larger object classes, and the development of generalizable tools suitable for inclusion in a graphics modeling toolbox. Coordination with hardware and software developers seeks to maximize the utility of these techniques and to ensure compatibility with hardware architecture. The development of a number of rendering techniques that significantly enhance the performance of Fig. 1. Only the image presented to the left eye in this stereo pair has texture graphics systems is expected. The mapping. Nonetheless, the resulting stereo percept appears textured. goal is to both extend the upper range of graphical rendering performance and to enable lower-end systems to produce visual imagery that currently can be produced only with high-end systems.

Point of Contact: M. Kaiser (650) 604-4448 [email protected]

Fig. 2. Another example of “hi-lo” stereo images. Here the left image is created with far more detail (that is, a larger number of polygons is used to model the object) than the one on the right. The resulting stereo perception appears high resolution.

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Entropy Masking in Visual prevent saturation of the limited dynamic range of the neural Displays response. Noise masking refers to Andrew B. Watson an inevitable reduction in visibility when a random component is added As part of NASA’s Human to the visual stimulus. Entropy Exploration and Development of masking depends on neither gain Space Enterprise and Aeronautics control nor randomness. Instead, it is and Space Transportation Technol- due to the observers lack of knowl- ogy Enterprise, the Vision Science edge about the obscuring back- and Technology Group at Ames ground, and it may be ameliorated Research Center is doing research on by increasing that knowledge the human factors of visual displays through learning. (a) and visual communication systems. The following experiments A primary thrust of this effort is to illustrate the essentials of entropy develop computational models of masking. The observer attempted to human visual performance that can detect the Gabor-function target be used in the engineering design of pictured in part (a) of the first figure; imaging and display devices. A first the target was obscured by the goal of human vision models is to addition of one of the masks shown predict visibility of arbitrary targets, in parts (b) and (c). The mask shown especially against noisy or cluttered in part (b) is a cosine luminance backgrounds that are typical of real grating with the same spatial fre- imaging environments. This problem quency as the target, and that shown is central to applications such as in part (c) is a sample of one-octave, image compression, flat-panel bandpass noise with a center spatial display design, sensor fusion, and frequency equal to that of the (b) design of helmet-mounted and other Gabor-function target. The two head-up displays. To meet this masks were equated in contrast challenge, a program has been energy so that they would have initiated involving experiments on equal effects on the contrast gain- visual masking: the interference of control system, that is, equivalent the background with the detection of contrast masking. visual targets. On each trial, the observer As a result of this research, a received two brief presentations on new category of visual masking has a cathode-ray-tube monitor. One been identified; it is called entropy contained a background only, the masking. Previous research over other contained a background plus many decades had identified two the target. The observer tried to principal varieties of visual masking: identify the presentation containing (c) contrast masking and noise masking. the target. The contrast of the target The former refers to a reduction in was varied from trial to trial in order Fig. 1. Visual target (a) and two visual sensitivity resulting from a to estimate the contrast required masks: cosine grating (b) and passive adaptive process. In effect, for 82% correct performance. To bandpass noise (c). Each mask is the gain of visual neurons is turned manipulate the degree of random- shown with the target added. down when there is a large amount ness, the bandpass mask was of pattern stimulation, in order to (1) new on each presentation

G LOBAL CIVIL AVIATION / Safety 17 Vertical Motion Simulator Advanced Simulator Ð10 Network William B. Cleveland Ð15 The Advanced Simulator Network (ASN) is an integration of Ð20 newer and higher-performance host computers and real-time data acquisition networks into the Ð25 Target threshold (dB) Vertical Motion Simulator (VMS) complex at Ames Research Center. The system provides significantly Ð30 better performance while retaining the powerful functionality of the None Cos Random Twin Fixed previous system. As shown in the Mask figure, the system consists of the data network, instrumentation input/ Fig. 2. Target thresholds as a function of mask condition. output (I/O), and a host computer together with its interface to the network. In a simulation setting, the (random condition), (2) the same masking effect of the bandpass noise pilot’s controls are input through the for both presentations of a trial but is due to the observer’s ignorance Cockpit CAMAC (Computer Auto- new for each trial (twin condition), about its structure (its entropy). mated Measurement and Control) or (3)␣ always the same (fixed It is thought that entropy mask- I/O, passed via the Data Highway condition). ing is the dominant form of masking and VME interface to the host The results are shown in the in many applied situations. Conse- computer where the aircraft’s second figure. The cosine mask quently, it is important to verify its response is computed and returned elevates the target threshold by a existence and properties in order to via the network highway elements to small amount (about 3 decibels), but enable optimal design of visual the motion, cockpit display, and the random condition produces communications systems. This work laboratory display devices. much more masking. However, the moves NASA closer to its goal of The performance increase of the twin condition shows that this developing a set of general human operational systems is dramatic. By masking is not due to randomness, factors engineering tools that will themselves the computers are twice since the masks are identical in the enhance the safety and effectiveness as fast as the computers of just two presentations of each trial. The of its Space and Aeronautics 4–5 years ago. Testing of the new fixed condition shows that with missions. CAMAC instrumentation shows a learning (640, 2176, and 3584 trials factor of 10 speed-up in perfor- Point of Contact: A. Watson were collected from the three mance over that of the old hardware. (650) 604-5419 observers), a significant reduction in These improvements reduce time [email protected] masking is obtained. Indeed, at the delays that cause a simulated aircraft end of learning, the threshold is to lose stability in comparison with similar to that for the cosine condi- the real aircraft. When there is no tion. It can be concluded that the real aircraft for comparison, incor- rect conclusions are often made

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Phase III, flight demonstration of real-time NN control and accident reconfiguration (1997, 1998). In 1996 major progress was made. Phase I NNs were generated that match the ACTIVE aerodynam- VME I/F Dec Alpha Data "highway" ics and were programmed into the F-15E computer. Three Phase I NNs were produced: (1) the Leavenburg- Marquardt network at Ames LaboratoryMotion Cockpit Research Center (ARC), (2) an active selection net at McDonnell Douglas CAMAC I/O Aircraft Corporation (MDAC), and (3) a neural fuzzy (ANFIS) at Fig. 1. Advanced Simulator Network. Tennessee State University. Four second-generation on-line when the simulator uses poor Intelligent Aircraft Control networks were developed for equipment or techniques. Although Phase II: Radial Basis Networks the VMS system can operate at System (MDAC), Recursive Higher Order 1000 hertz when only I/O is per- Charles C. Jorgensen Neural Network (Washington formed with the motion, laboratory, University), Feedback Linearization and cockpit subsystems, adding the The intelligent aircraft control Neural Net (ARC), and Dynamic Cell typical aircraft model allows a system provides a safety-oriented Structures (ARC). 200-hertz operation. Most simula- flight control technology that can Two on-line aerodynamic tions are near the 60-hertz rate of the efficiently deal with off-nominal and derivative estimation methods were associated graphics generators, but unforeseen changes in aircraft developed by MDAC: Kalman the ASN system performance reserve systems or operating environments. Filtering/Recursive Prediction and will allow larger model options and The effort accomplishes reconfig- Locally Weighted Regression. Three I/O rates when needed. urable flight control under damage Linear Quadratic Regulator Methods Early in FY96, the first of the scenarios by using a modified F-15 were designed by MDAC: (1) Robust systems was installed into an aircraft’s (ACTIVE) differential canard Servo, (2) Setpoint Regulator, and Interchangeable Cab fixed-base and vectored thrust capabilities. This (3)␣ SOFFT, Langley Research Center. simulation laboratory, where it was effort is a four-year cooperative A full-scale parameter sensitivity tested and perfected before it was research contract begun in 1995. analysis was begun for performance installed into the VMS. Before the It comprises three phases: Phase I, envelope, stability, and robustness end of FY96, the VMS system had create neural nets (NNs) that model using the new techniques. A real- been used in five simulations stability and control derivatives in time Ricatti equation solver was including astronauts flying the space the pitch, roll, yaw, lift, and side developed (MDAC), and a new shuttle vehicle. force axes of the F-15 ACTIVE Virtual Reality test environment was aircraft in 1995–96 (see the figure developed by ARC using a nonlinear Point of Contact: W. Cleveland (see Color Plate␣ 2 in the Appendix)); F-15E model. (650) 604-5352 Phase II, develop on-line NNs to Point of Contact: C. Jorgensen [email protected] process aircraft sensor data in real- (650) 604-6725 time and update the stability and [email protected] control derivatives in 1997; and

G LOBAL CIVIL AVIATION / Safety 19 G GLOBALLOBAL C CIVILIVIL A AVIATIONVIATION/ / A wide range of traffic environ- the other extreme is the en route A␣␣AFFORDABILITYFFORDABILITY ments is found in the National area near busy terminal areas where Airspace System. At one extreme is aircraft must be merged for spacing en route airspace away from busy and sequencing. The system is Facilitating User Route terminal areas consisting of aircraft supplied with real-time tracking Preferences in En Route generally not constrained by traffic radar and flight plan information Airspace or weather. If traffic density is low, from the air-traffic control facility’s very little ground-based air-traffic host computer. The Airspace Tool Bob Vivona, Mark Ballin, control intervention is required. At (AT) is designed to achieve user Steve Green, Ralph Bach, Dave McNally Radar tracks, Flight plans Under the current air-traffic system, aircraft generally must fly on fixed routes. On the other hand, the

Air Transport Association estimates Conflict resolution that its member airlines could save advisories $1.2 billion per year if they were Airspace Sector able to fly direct routes. However, tool tool relaxing existing routing restrictions Clearance information will require new conflict-prediction Aircraft and resolution automation to help controllers maintain required Fig. 1. Operational concept for user-preferred routing in en route airspace. separation while minimizing their effect on their workload. Although some automation now exists (for example, Conflict Alert, which uses a 2-minute prediction based on previous radar hits), for the most part air-traffic controllers detect conflicts by visually monitoring radar tracks and, when necessary, issuing resolution advisories to aircraft to avoid loss of separation (5 nautical miles horizontal, 2000 feet vertical). Conflict-prediction and resolution tools for controllers are being developed under the Advanced Air Transportation Technology program at Ames Research Center. The objective of this work is to develop an operational concept and associated software for use of conflict- prediction information in order to generate minimum-cost resolution advisories to facilitate increased Fig. 2. Sample airspace with four sectors showing two typical conflict user route preference in en route scenarios. airspace.

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efficiency for long time-horizon dollars annually in direct operating therefore, to estimate the probability (15–25 minutes), generally inter- costs if the Federal Aviation Admin- that a conflict will occur between a sector conflict-predictions by istration (FAA) would relax routing given pair of aircraft. This conflict- generating resolution advisories restrictions and adopt a policy of probability estimate is important for based on minimum cost deviation “free flight.” The safety and effi- determining both how and when to from user-preferred routes. Reduced ciency of free flight will benefit from optimally resolve conflicts. controller workload is also achieved automated conflict-prediction and An error model and an algo- through inter-sector conflict resolu- resolution advisories to help air- rithm have been developed to tion. The Sector Tool (ST) facilitates traffic controllers maintain the determine conflict probability. Based controller planning within a sector required separation between aircraft on analysis of actual air-traffic data, for short time-horizon conflict- while minimizing the effect on the trajectory-prediction errors are prediction, trial plan (“what if”) trajectories. Trajectory prediction modeled as being normally distrib- solutions, and transition to the is less certain the further in advance uted (Gaussian), with the along-track terminal area (see first figure). a prediction is made, however, error growing with prediction time The second figure shows a so conflicts cannot be predicted as a result of wind modeling error, simple example of en route airspace exactly. A method is needed, as shown in the first figure. The two with four sectors and two sample conflict scenarios. In both cases a Path minimum-cost resolution advisory crossing is computed by the AT. For the case angle Prediction time in which the conflict is predicted across sector boundaries, the AT passes a suggested advisory to the appropriate sector. Each resolution is checked by the sector controller with the aid of the ST, and, if acceptable, is issued to the aircraft by the controller. Predicted Minimum trajectories predicted The Center-TRACON Automa- separation tion System software is being used as a baseline for development, simulation, and field testing of the operational concept. Prediction Point of Contact: D. McNally error (650) 604-5440 ellipse [email protected]

Conflict Probability Estimation for Free Flight Russell A. Paielli, Heinz Erzberger

Predicted time The Air Transport Association estimates that the U.S. airline industry could save several billion Fig. 1. Trajectory prediction error ellipses.

G LOBAL CIVIL AVIATION / Affordability 21 numerical integration. Efficiency is important because the algorithm is intended to run in real time. The high efficiency also makes the Combined algorithm a convenient tool for error ellipse analyzing the effects of various parameters. The algorithm was programmed in C++ and successfully tested by Monte Carlo simulation over a wide range of encounter geometries. It has Circular also been integrated into the Center/ conflict zone TRACON Automation System (CTAS). CTAS is a large software system developed at Ames Research Center to help air-traffic controllers do their job more efficiently and with less stress. In this context, CTAS predicts the trajectories, determines the states of the aircraft at the predicted point of minimum separation, and sends that state information to the conflict-probability algorithm.

Relative velocity The probability results are then used by CTAS to determine if a predicted Extended conflict zone conflict should be displayed to the controller. The system is currently Fig. 2. Encounter geometry. being tested on both live and recorded air-traffic data that are sent to Ames on a dedicated line from error covariances for an aircraft pair conflict zone. In three dimensions Denver Center. are combined into a single equiva- the basic concept is similar but more Point of Contact: R. Paielli lent covariance of the relative difficult to illustrate. (650) 604-5454 position. The second figure shows A coordinate transformation [email protected] the combined error ellipse (based on based on the Cholesky decomposi- the combined covariance) centered tion (“square-root” factorization) of on one aircraft and the circular the combined covariance is used to conflict zone centered on the other. derive an analytical solution for the The extended conflict zone is the conflict probability. If the Gaussian projection of the circular conflict error model were exact, this solution zone in the direction of the relative would be exact for level flight and a velocity. In two dimensions the good approximation for nonlevel conflict probability is the volume flight. This analytical solution is under the probability-density computationally far more efficient function that is within that extended than an alternative solution based on

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Conflict Prediction Algorithms: Initial Field Denver Center Test NASA boundary Lear Jet Dave McNally, Bob Vivona, Karl Bilimoria, Gerd Kanning, En route traffic Steve Green, Ralph Bach, Allan McCrary, Ed Lewis En route J94 traffic The Federal Aviation Adminis- Scott Bluff tration (FAA) is responding to the needs of the aviation community by exploring the concept of “free flight” for aircraft flying under instrument Fig. 1. Flight profiles for initial field test of en route conflict prediction. flight rules. In free flight, en route aircraft fly user-defined trajectories (defined by pilots or airlines) with and the FAA Host computer tracker, before the predicted time of mini- only minimal air-traffic control (ATC) and to get an initial look at opera- mum horizontal separation and adjustments to avoid restricted tional issues pertaining to en route continued just beyond minimum airspace and loss of separation from conflict prediction. The Ames Lear separation. other aircraft. To facilitate user- Jet flew at angles of 0, 45, 90, 135, A preliminary analysis of the preferred routing in all en route and 180 degrees with respect to jet data shows that minimum horizontal environments, an extension of the route J94 near Scotts Bluff (see separation was predicted with ground-based Center-TRACON figure) to create (horizontal plane) 1.5-mile accuracy during the Automation System (CTAS) is being conflicts with normal Center traffic, 15–25 minute period before the developed under the Advanced Air while maintaining normal safe time of actual minimum separation. Transportation Technology program altitude separation at all times. The This is well within the FAA separa- at Ames Research Center. The first NASA Jet recorded differential tion criteria of 5 miles for en route step is to add en route conflict- Global Positioning System (GPS) airspace and 3 miles for the terminal prediction capability to the CTAS position and velocity data to evalu- area. These results are based on software baseline. When fully ate the trackers. A version of CTAS horizontal separation data related to developed, en route conflict- software, modified for en route the distances between the NASA Jet prediction and resolution capability conflict prediction, processed live and each of 59 other aircraft of should achieve many free-flight radar, flight plan, and wind data for various types over 8 days of test benefits without significantly altering all aircraft in the Denver Center. flights. current ATC procedures or requiring Predictions of minimum horizontal Point of Contact: D. McNally modification of airborne equipment. separation between the NASA (650) 604-5440 An initial field test was con- aircraft and each selected aircraft [email protected] ducted from September 24 through were begun nominally 20 minutes October 8, 1996, at the Denver Air Route Traffic Control Center (ARTCC or “Center”). The purpose was to conduct an initial evaluation of an en route conflict-prediction software, to evaluate an advanced tracker developed by the BDM Corporation

G LOBAL CIVIL AVIATION / Affordability 23 divided between pilots and control- displayed. Under the present system lers, the safety of the overall system this kind of “situation awareness” is Assessing Controller will depend heavily on the ability of facilitated by virtue of traffic patterns Performance Under controllers to perform their jobs that are orderly and have a familiar Simulated Free-Flight well. One of the tasks of controllers structure. Research on human will be to look at situation displays cognition suggests that reducing the Conditions and understand the traffic, including structure present in traffic flows Roger Remington, James Johnston, the position and paths of the aircraft might make it more difficult for Eric Ruthruff, Maria Romera

Traditional air-traffic control procedures restrict air traffic to designated routes and altitudes, analogous to highways in the sky. It is well understood that these regulations, although promoting safe air travel, impose a price on the airlines in increased flight time and increased fuel consumption. NASA is presently working with the Federal Aviation Administration (FAA) to develop plans to relax these constraints on air traffic so that airlines would be free to choose routes that minimized delays and fuel costs. Free-flight refers to a family of (a) proposed concepts ranging from the relaxation of a few constraints to total freedom of choice of flightpath. The goal of this joint NASA-FAA activity, the Advanced Air Transpor- tation Technology program, is to ensure that the relaxation of constraints on airspace operations do not compromise safety. The Cogni- tion Laboratory at Ames Research Center has been investigating the effects that relaxing airspace constraints can have on controller performance. The extent to which constraints can be relaxed and free flight enhanced is assumed to depend, in (b) part, on the workload of flightcrew and air-traffic control (ATC). Regard- Fig. 1. A traffic display. (a) With route restrictions. (b) Without route less of how future responsibility is restrictions.

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assisted conflict detection. The 40 overall results to date provide no reasons for pessimism about the 35 feasibility of considerable progress toward the objective of free flight. 30 Point of Contact: R. Remington 25 (650) 604-6243 [email protected]

15 Routes Reaction time (sec) Routes— Evaluating Cockpit Display 10 alt restrictions of Traffic Information Free Displays and Route 5 Free— alt restrictions Assessment Tools for a 0 12 16 20 Free Flight Environment Number of planes Vernol Battiste, Walter W. Johnson

Fig. 2. Conflict detection time as a function of number of aircraft on screen The Radio Technical Commis- for the four restriction conditions. sion for Aeronautics (RTCA) Task Force 3 report on free flight recom- mends the immediate initiation of controllers to maintain situation shows a traffic display with the same “the development of standards for a awareness. number of aircraft in which route cockpit situational awareness display A series of experiments has been restrictions have been eliminated. of traffic information.” In response conducted to determine empirically In addition, the number of planes to these recommendations, the whether controller situation aware- displayed was systematically varied. Advanced Air Transportation ness is hindered by the loss of traffic The second figure shows the results Technologies Program and the Flight constraints under free flight. To of one of the experiments in which Management and Human Factors measure situation awareness, the experienced controllers detected the Division at Ames Research Center experiments tested the speed with presence of conflicts with the aid of have initiated research on display which controllers could find con- a computer conflict-assessment tool. designs and formats to support flight flicts in traffic displays. The experi- The number of aircraft had strong deck self-separation during free- mental design contained four effects on performance; detection flight operations. conditions: the status quo (both fixed times increased with increased The primary goals of this effort routes and fixed altitude restrictions), number of planes in all conditions. are to (1) conduct research to free flight (neither fixed routes nor Removing route restrictions did not support the development of display fixed altitude restrictions, fixed negatively affect performance, but guidelines, and (2) evaluate and routes only, or fixed altitude restric- removing altitude restrictions did design cockpit display concepts and tions only. Part (a) of the first figure have a modest negative effect. prototypes in support of cockpit- shows a traffic display with route Similar results have been obtained based separation during nominal restrictions; part (b) of the first figure in conditions without computer- and off-nominal operations from departure to arrival including the en route and transition phases of flight.

G LOBAL CIVIL AVIATION / Affordability 25 Three critical areas have been identified in the display design GS 473 TAS 473 OCS TRK254 MAG 1822.4z research: (1) alerting; (2) situational 174 NM awareness; and (3) conflict resolution. These three areas are interre- lated, and require an integrated 24 27 approach to arrive at good Human Centered Design recommendations. The research approach has been +10 to identify attributes of displays that are critical to crew alerting and +00 conflict resolution, and also to apply 80 Ð20 basic and advanced principles of +20

good display design. Two critical Ð30 attributes that have been identified Ð23 TWA30 +00 are the surveillance data needed and the format of the display. The main principles guiding the Cockpit Display of Traffic Information (CDTI) design effort are to minimize head- +00 ALERT down time and dwell time, to reduce +00 CTA 04:21 scan frequency, and to improve GPS IRS (3) information extraction. Another principle is minimizing the effect of alerts by providing enough advanced CONFLICT warning so pilots can have adequate 0 0 0 0 +10 Ð25 +25 Ð10 Ð500 +500 time to plan for potential problems. +5 Ð20 +20 PREDIC Finally, the design considers that Ð50 +50 Ð30 +30 Ð1000 +1000 +10 other cockpit duties prevent the SPD HDG VERT PREDICT IDENT crew from focusing their full atten- SPD MIN tion on the task of self-separation. Based on these principles and Fig. 1. Airborne Management of En Route Separation (AMES) display and guidelines, an initial prototype Route Assessment Tool (RAT). Airborne Management of En route Separation (AMES) display was designed. To support the assessment evolving four stage (threat-level) line pilots during a Crew Vehicle of alternative route planning, a depiction of the traffic, based on the Systems Research Facility B-747 Route Assessment Tool (RAT) was output of a collision alert system simulation of free-flight operations. designed and incorporated into the developed at the Massachusetts During the simulation the AMES display design. The AMES display Institute of Technology. In addition, display was compared with a more prototype was integrated with the this display allowed pilots to depict basic display that had only one level B-747 Navigation display and the the predicted location of traffic up to of alerting and no RAT tool. This RAT controls were located on the 10 minutes in the future, and to simulation examined performance top of the dash (see figure). The assess the safety of pilot-proposed during eight en route traffic sce- display was a two-dimensional route deviations. narios incorporating multiple track-up god’s eye view of the traffic The AMES display and RAT “traffic” aircraft, and one “intruder” situation that provided pilots with an were evaluated by 10 Boeing 747

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aircraft on a conflict course, and when visibility is limited to 300 to augmentations to the scene, have used flight procedures based, in part, 700 feet by fog or rain. been developed (see first figure). on FAA rules guiding separation Two display technologies were The superimposed text symbols, the during VFR flight. The data from the investigated: a head-up display and “Inner, Alpha/Bravo” format, repre- simulation show that pilots using the an audio collision avoidance system. sents the current runway or taxiway AMES display were able to maintain In the first, taxi guidance symbols segment (“Inner Taxiway”), the last a significantly wider margin of safety are shown on a head-up display intersection passed (“Alpha”), and between own-ship and intruder, and (HUD). A HUD is a clear, glass the next intersection upcoming a lower overall level of conflict display mounted in the aircraft such (“Bravo”). probabilities between own-ship and that the pilot can see through it to The pictorial scene augmenta- intruder, and between own-ship and view the out-the-window taxiway, tions include visual enhancements other context aircraft. The analysis and at the same time see information that aid the pilot in following the also showed no increase in the that is reflected on the display itself. taxiway clearance and completing amount of maneuvering with the This allows for display information turns. Using satellite positioning, the AMES compared with the basic viewing while still maintaining out- symbology is projected virtually in display, and in fact showed less the-window viewing. 3-D such that the symbols move and maneuvering with the AMES display The taxi symbology for the change size in the same manner as if under some circumstances. Crew HUD is a subsystem of the Taxiway they actually existed in the out-the- comments on the display design Navigation and Situation Awareness window scene. We have termed this were all very favorable, and sug- (T-NASA) System. The other sub- “scene-linked symbology.” Vertical gested that self-separation would be systems are a perspective moving- cones on the side of the commanded possible if these types of displays map display, showing the plane’s taxiway path depict the cleared and tools were available on the position at the airport, and three- route on the HUD in superimposed flight deck. dimensional (3-D) audio which symbols. These are conformal and alerts to the direction of potential represent a virtual representation of Point of Contact: V. Battiste/ traffic incursions. For this project, the cleared taxi route on the HUD. W. Johnson superimposed HUD symbols The side cones and the centerline (650) 604-3666/3667 showing current location and markings are shown repeated every [email protected] ground speed, as well as pictorial [email protected]

Cockpit Displays for Low-Visibility Taxiing David Foyle, Elizabeth M. Wenzel, Durand R. Begault

These cockpit display projects (as part of NASA’s Terminal Area Productivity (TAP) program) are aimed at developing candidate cockpit display and audio technology for the improvement of civil transport (airline) taxi performance Fig. 1. Scene-linked symbols (in white) superimposed on runway scene. for navigation and traffic avoidance,

G LOBAL CIVIL AVIATION / Affordability 27 50 feet down the taxiway. The vertical development and constant 3-D audio warning for GPS equipped spacing should yield increased blunder avoidance obstacle under RVR 300 conditions (e.g., vehicle, capability for estimating ground other aircraft) speed, drift, and look-ahead capability for turns. Turn “countdown” Critical warnings are shown in which each distance turn has countdown (4, 3, and 2) centerline lights that are 300, 200, 3-D audio for and 100 feet, respectively, before Angle ∆ directionalized each turn. This gives added distance warning signal cues for the turn. Virtual turn signs (with the arrows) give an added cue that a turn is necessary. In addition, the angle of the arrow on the sign Pilot hears represents the true angle of the virtual audio warning from turn (that is, 30 degrees right for a the same angle 30-degree right turn). All of the HUD symbols are scene-linked (virtually projected as if they were real objects Fig. 2. Illustration of the 3-D audio GCAS display for the terminal-area in the world), allowing the pilot to productivity program. process the symbology in parallel with other traffic, including possible incursions. sensing (DGPS) to track aircraft and main conclusions of the study were Simulation results have shown other vehicles on the ground, and that an audio GCAS system would that the taxi HUD symbology allows then uses this information to provide be useful for avoiding potential pilots to taxi faster in low-visibility visual and auditory situational incursions under both normal and conditions and essentially eliminates awareness by means of advanced low-visibility conditions, and that an straying off of the cleared ground guidance systems and displays. auditory system presenting incursion taxi route. These benefits have the A 3-D auditory display is used as a alerts would be a useful adjunct to added bonus of also being associ- ground collision avoidance system a moving-map display. A positive ated with decreased workload. (audio GCAS; see second figure) preference was also found for the The second display technology to provide immediate situational stereo headsets that were used to investigated was a 3-D audio awareness of crossing runways, of provide the 3-D audio cueing. Ground Collision Avoidance System potential incursions, and of the Point of Contact: D. Foyle/ (GCAS) and navigation system— aircraft being “off-track” (deviating E. Wenzel spatially localized auditory traffic from centerline). (650) 604-3053/6290 and navigation alerts. Additionally, A full-mission simulation study [email protected] the Crew Roles and Procedures was run using 12 crews in a [email protected] project is assessing the effect of B-747-400 simulator. It was hypoth- these advanced technologies on the esized that there would be a signifi- cockpit crew and controllers, as well cant pilot preference for an audio as recommending procedure modifi- GCAS system to be included on the cations as necessary. flight deck. That preference for the Broadly stated, the TAP initiative audio GCAS system was found. The utilizes differential global position

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Multi-Sensor Image Registration Misha Pavel, Al Ahumada, Barbara Sweet

The use of various imaging sensors that can penetrate obscuring visual phenomena (such as fog, (a)␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣(b)␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣(c) snow and smoke) has been proposed to enable aircraft landings in low- Fig. 1. Forward-looking infrared image (a), visible-light image (b), and the visibility conditions. Images can registered image pair (c). be obtained from both active and passive sensors that are sensitive to electromagnetic energy in the relative to each other which make Flow Visualization of a visible, infrared, and millimeter registration more challenging. Full-Scale Rotor in Hover wavelengths. Images can also be A standard method of registering constructed from database informa- two images is to find a spatial Benton H. Lau, Alan J. Wadcock, tion, by rendering an image of the warping of one image that mini- Gloria K. Yamauchi database viewed from the estimated mizes the sum of the squared position of the aircraft. The focus of differences between the two images. The rotorcraft industry has the current research effort is the However, for images from different strongly recommended that wake development of image registration sensors, this does not work because geometry and vortex strength be (superimposition) techniques in the images are not the same when measured in addition to airloads support of this application. the warping is correct. and acoustic measurements during Two challenges specific to The figure shows results from rotorcraft wind-tunnel tests. The multisensor registration must be NASA’s new method. It estimates existing aeroacoustic analyses overcome. First, the features in two the image polarity relationship require all three kinds of data for different sensor images can be quite separately in local regions and drops validation purposes, especially when different. For example, the contrasts regions from the difference measure predicting blade-vortex interaction can be reversed; the runway might that do not correlate well locally. (BVI) noise. Accounting for blade be bright in a visible-light image and The new method makes it possible deflection is also important in dark in an infrared image. Previously to find the correct spatial transforma- accurately predicting BVI noise and derived procedures for image tion despite local differences in in validating aeroelastic analyses. In registration rely on a high degree of feature polarity and despite image response to industry, Ames Research common features between the two features that are unique to a sensor. Center initiated a test program to images. However, for this applica- evaluate several flow-visualization Point of Contact: A. Ahumada/ tion, there is no guarantee that this and blade-displacement measure- B. Sweet exists; features apparent in one ment techniques for a full-scale (650) 604-6257/0006 sensor might not be apparent in the rotor. Three techniques were [email protected] other. Secondly, the two sensors are evaluated on an XV-15 tiltrotor in [email protected] usually sited at different locations. hover in the Ames 80- by 120-Foot This differential positioning can Wind Tunnel. produce distortions of the images

G LOBAL CIVIL AVIATION / Affordability 29 Flow patterns on a rotating range of thrust conditions including and illuminated the entrained smoke blade can be visualized using rotor stall. in the rotor wake. Images of the fluorescent microtufts. Thousands Rotor-wake geometry can be rotor-wake geometry were recorded of fluorescent microtufts were measured using laser-sheet and flow on video at several thrust conditions. installed on the upper surface of a visualization (see figure). A smoke In addition to testing the standard rotor blade. When illuminated by dispenser was installed near the tiltrotor blades, a series of subwings a powerful ultraviolet strobe, the rotor tip, and an optics pod was were tested and their effects on wake blade motion was frozen and the placed below the rotor plane on the geometry and tip-vortex roll-up were microtufts displayed the flow wind-tunnel floor. When fed with a evaluated. pattern. The microtuft images were laser beam via a fiber optic cable, Blade displacement was mea- subsequently captured on film over a the pod generated a thin laser sheet sured using a stereo imaging technique. Retro-reflective targets were placed along the blade span on the upper surface. Two asynchronous video cameras and strobes mounted in the wind-tunnel ceiling were used to capture the frozen blade motion. The blade displacement or deforma- tion can be deduced from the positions of these targets. The success of these test techniques provides promising results for hover testing of a full-scale rotor. The test techniques can be applied to forward flight testing.

Point of Contact: B. Lau (650) 604-6714 [email protected]

Skin-Friction Measurements on a Hovering Rotor Alan J. Wadcock, Gloria K. Yamauchi

A technique for acquiring skin- friction measurements on a fixed wing using a fringe-imaging skin- friction (FISF) technique was developed at Ames Research Center in the early 1990s. As long as the flow conditions are steady, as they are in Fig. 1. XV-15 tiltrotor and laser sheet setup in the 80- by 120-Foot Wind hover, this technique can also be Tunnel at Ames. applied to rotary wings. During a

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methods, an experimental validation .010 study was conducted using test results from model- and full-scale .008 tests to compare with flight-test data. Accurate measurements of rotorcraft performance as measured .006 in a wind tunnel are strongly influ- x

Cf enced by the test-section configura- .004 tion, that is, whether it is a closed or open jet. The influence of wind- tunnel walls on the induced velocity .002 of lifting bodies has been studied by many researchers over the years. 0 Methods have been developed to 0 .2 .4 .6 .8 1.0 adjust the angle of attack and x/c dynamic pressure for fixed-wing aircraft in wind tunnels to approxi- Fig. 1. Chordwise skin-friction coefficient. mate free-flight conditions. These methods have largely been adopted hover test of a full-scale XV-15 station of r/R = 0.24 are shown in by the rotorcraft community with tiltrotor in the 80- by 120-Foot Wind the accompanying figure for a tip very little testing to verify their Tunnel at Ames, the FISF technique Mach number of 0.59, a thrust applicability to helicopter rotors was demonstrated for the first time coefficient of 0.0035, and a and flight-test measurements. on a rotor. Reynolds number of 1.1 million. Tests conducted by the The objective of this first The measurements clearly indicate Deutsche Forschungsanstalt für demonstration was to determine the the location of the transition from Luft- und Raumfahrt e.V. (DLR) in practicality of the FISF technique laminar to turbulent flow. the Duits-Nederlandse Wind Tunnel when applied to a full-scale rotor. (DNW), under the auspices of the Point of Contact: A. Wadcock Since the FISF technique had not U.S. Army/German Memorandum (650) 604-4573 been used previously in a rotating- of Understanding on Cooperative [email protected] flow environment, the effect of Research in the Field of Helicopter centrifugal force on the fringe Aeromechanics, have provided data patterns was a concern, as were the suitable for evaluating these meth- transient effects caused by starting ods. A 40% scale-model BO-105 and stopping the rotor. The effect of Rotor Data Correlation rotor was tested in five different transients was minimized by remain- Randall Peterson wind-tunnel test sections: (1) 6- by ing on the test condition for a 6-m closed, (2) 8- by 6-m closed, suitable length of time. The effect of The use of wind-tunnel test (3)␣ 8- by 6-m open slots, (4) 9.5- by centrifugal force was shown to be measurements, flight-test measure- 9.5-m closed, and (5) the 8- by 6-m negligible, once the oil-film thick- ments, and analytical predictions open jet. These data along with full- ness was reduced sufficiently. plays a key role in the development scale data from an Ames 40- by Chordwise skin-friction coefficient of new rotor systems. Such tests are 80-Foot Wind Tunnel test and a measurements were acquired at one typically performed by using a range DLR flight-test program provided a low-thrust condition at three blade of rotor-system sizes and wind- means to evaluate wind-tunnel wall- radial stations. Measurements on the tunnel test facilities. To ensure the correction methods specifically for XV-15 tiltrotor blade at a radial accuracy of wind-tunnel testing helicopter rotors. Good correlation

G LOBAL CIVIL AVIATION / Affordability 31 45 knots Canard Rotor/Wing Hover Test

.007 Stephen Swanson, John Madden Experimental data CAMRAD/JA — no wall correction CAMRAD/JA — with wall correction In a joint program between .006 NASA and McDonnell Douglas Helicopter Systems, a one-half-scale .005 rotor model of the McDonnell Douglas Canard Rotor/Wing (CRW) rotorcraft was tested in the 80- by .004 120-Foot Wind Tunnel at Ames σ /

P Research Center. This test was C .003 conducted to evaluate the hover performance of the unique elliptical- airfoil rotor being planned for the .002 CRW. The CRW is a stoppable-rotor design which can hover and fly at

.001 low-speeds like a conventional 0 .02 .04 .06 .08 .10 .12 helicopter, whereas in its stopped- σ rotor mode it can fly at high speeds CT/ comparable to those of fixed-wing aircraft. Initial concepts include a Fig. 1. Rotor power with and without angle-of-attack correction applied to land- or ship-based medium-range the trim conditions of the rotor in the analysis. vertical takeoff and landing, remotely piloted vehicle. A two-bladed teetering rotor is of rotor power over a range of influenced by the presence of the used to generate the required lift for advance ratios for these three wind-tunnel walls. Using the wall- hover and low-speed forward flight. datasets was shown using wall- correction method of Glauert, the Once the rotorcraft is at a sufficient correction methods after accounting angle of attack of the rotor system in forward velocity, the required lift for trim differences between the the tunnel was corrected and used in generation is transferred from the datasets. the trim conditions of the CAMRAD/ rotor to a canard and horizontal tail. Recent rotor-data correlation JA analysis. As shown in the figure, What is unique about this rotor is work has focused on the ability of the accuracy of predicted rotor that it is driven by high-pressure analytical prediction methods such power is significantly improved air exhausted at the rotor tips as as CAMRAD/JA (Comprehensive when the angle-of-attack correction opposed to the conventional heli- Analytical Model of Rotorcraft of Glauert is applied to the trim copter in which the rotor is shaft- Aerodynamics and Dynamics, conditions of the rotor in the driven. In the flight vehicle, Johnson Aeronautics) to accurately analysis. The analytical predictions conventional turbofan engines are predict rotorcraft performance. Full- of rotor power as a function of rotor used to supply the high-pressure air scale BO-105 rotor-system data thrust using a free-wake analysis to the rotor. Because the CRW’s acquired in the Ames 40- by 80-Foot are shown. rotor is stopped to allow high-speed Wind Tunnel are being used in this Point of Contact: R. Peterson forward flight, the rotor’s airfoil cross analytical study. From previous (650) 604-5044 section must be elliptical. This is a experimental comparisons, it was [email protected] compromise between the optimum shown that the rotor-performance measurements were strongly

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Fig. 1. Isolated rotor model installed in the Ames 80- by 120-Foot Wind Tunnel. airfoil shape for conventional rotor gases of the CRW’s engine. The actual and predicted internal flight and that for high-speed figure shows the isolated rotor pressure measurements indicated stopped-rotor flight. installed in the test section and higher than expected duct losses The fixed-wing aerodynamic connected to the high-pressure air within the rotor internal piping. characteristics of the complete system. Preliminary results indicate Point of Contact: S. Swanson aircraft were evaluated in earlier that the rotor was capable of gener- (650) 604-4565 tests. In this recent test, the isolated ating the required lift for takeoff and [email protected] rotor was evaluated in hover in the hovering flight. Comparisons with Ames 80- by 120-Foot Wind Tunnel; predicted aerodynamic performance that tunnel was used because it has showed that the actual thrust the unique capability to provide generated was greater than predicted heated, high-pressure air that could for the same power input. On the be used to simulate the exhaust other hand, comparisons of the

G LOBAL CIVIL AVIATION / Affordability 33 In-flight Dynamic Stall dynamic-stall phenomena. UH-60A test condition. The two pitching- airloads data are available to NASA’s moment departures near 280 and Research customers for similar studies through 355 degrees have been clearly Robert Kufeld, William Bousman an electronic database and search identified as dynamic-stall events. engine called “TRENDS,” which is The two pitching-moment departures The objective of this work is to maintained at Ames Research near 95 and 135 degrees have been improve the complex dynamic-stall Center. linked to passage of shock waves aerodynamic models of a helicopter The figure shows some of the over the airfoil; the final pitching- rotor in high-speed, high-load complex loading a helicopter rotor moment departure near 50 degrees conditions. The improvement of is subjected to during a high-speed appears to be caused by a combina- these models should serve to reduce turn. The data show the measured tion of two effects: supersonic the design and development cost pitching-moment calculation derived aerodynamic and dynamic-stall of new helicopters, because the from pressure transducers located vortex shedding. These data show dynamic-stall condition is the at radial station r/R = 0.92, at an the need for dynamic-stall model driving force in determining the advance ratio of 0.39 and a load improvement at both the traditional strength of the helicopter control factor of 1.5. The figure clearly low-speed range of the fourth system. Test conditions were identi- shows the five rapid and large quadrant and the unexpected high- fied and studied from the flight- negative pitching-moment depar- speed range found in the first maneuver data collected during the tures the blade experiences as it quadrant of the rotor. UH-60A Airloads Program, which makes one revolution during this provides information about the Point of Contact: R. Kufeld (650) 604-5664 [email protected]

.02

Stall Control of Helicopter 0 Rotors ) M

C Khanh Q. Nguyen 2

A control system based on Ð.02 blade-pitch actuation was developed to suppress stall on helicopter rotors. Stall suppression would allow the helicopter flight envelope to be Section moment (M expanded and would alleviate stall- Ð.04 induced loads and vibration. The control system was implemented in a comprehensive rotorcraft analysis, which was based on a Ð.06 finite-element method and which 0 45 90 135 180 225 270 310 360 included unsteady aerodynamic Blade azimuth (deg) effects (dynamic stall) and nonuni- form inflow models. The stall- Fig. 1. Section moment versus rotor azimuth for r/R = 0.920 in a high-speed suppression system is based on a turn; advance ratio = 0.390 and load factor = 1.50. transfer-matrix approach; it employs

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a stall index as a measure of stall. figure in which the stall regions are In general, however, stall The results showed that stall could shown without the system (part (a)) suppression did not guarantee effectively be suppressed using and with the system (part (b)) at a performance improvements. The higher harmonic control at both high-thrust, high-speed flight condi- results also showed the distinction cruise and high-speed flight condition. The control amplitude was between stall suppression and tions. The effectiveness of the stall- small, less than 1 degree. performance improvement with suppression system is shown in the active control. When the controller aimed to reduce the shaft torque, rotor-performance improvement could be achieved, but with a small degradation in stall behavior. (a) Point of Contact: K. Nguyen (650) 604-5043 .4 [email protected]

.2 Lift excess .1 Apache AH-64D Flight

0 .4 Test Predictions .5 Earl P. N. Duque 90 .6 180 .7 .8 Recent design changes to the Azimuth (deg)270 r/R .9 AH-64D (Apache) helicopter have 360 1 created unfavorable handling qualities that may be caused by changes in the aerodynamic flow field. Engineers at McDonnell (b) Douglas Helicopter Systems needed to quickly understand the flow

.4 characteristics and to evaluate potential ways to alleviate the .3 problem. Computational fluid dynamics (CFD) is an ideal tool for .2 examining the effect of late-cycle Lift excess .1 design changes because it is much faster and cheaper than flight testing. 0 .4 The objective of this project was .5 90 .6 to use CFD methods to study the 180 .7 flow field around the helicopter in its .8 Azimuth (deg)270 r/R current configuration and then with .9 several variations which designers 360 1 proposed to improve the handling Fig. 1. Stall regions over rotor disk without the stall-suppression system (a) qualities. The simulation results had and with the system (b). to be obtained quickly in order to

G LOBAL CIVIL AVIATION / Affordability 35 decide which designs would be built Rotor-Wake/Fuselage method used to model the TRAM and tested in flight. isolated-rotor configuration is a Inviscid simulations were done Interaction combination of the OVERFLOW with the TIGER code by John Melton Paul M. Stremel computational fluid dynamics code of Ames Research Center (ARC). Its and the PEGSUS domain connectiv- unstructured Cartesian formulation The interaction of the wake ity program. The isolated-rotor largely bypasses the time-consuming generated by a rotor with the configuration consists of a rotor and and tedious task of grid generation, fuselage of the vehicle has profound a motor/gearbox assembly. In the allowing for fast turnaround of very effects on the overall efficiency of current investigation, the rotor is complicated models. Results from the vehicle. These effects have been represented by an actuator-disk the initial geometry (see figure (see clearly demonstrated in flight as model. Results were computed for vehicle vibration and download. Color Plate 3 in the Appendix)) CT = 0.14 at angles of incidence of influenced two of the proposed Although they are clearly demon- 0 and 15 degrees. The results are design solutions. Subsequent study strable in flight, the quantitative shown in the first figure (see Color of five new designs showed that one aspects of the interactions are not Plate 4 in the Appendix) for 0-degree did not warrant further investigation. clearly understood. Numerous incidence and in the second figure Since the validity of an inviscid numerical and experimental investi- (see Color Plate 5 in the Appendix) approximation is questionable in a gations have been conducted in for 15-degree incidence. Shown in complex, vortex-dominated flow, efforts to better understand the rotor- each figure are the vertical velocity intensive study of a geometrically wake/fuselage interaction. However, contours and the flow-field stream- simplified model (the isolated each of these investigations concen- lines. The vertical velocity contours fuselage without engine, wing, or trated on a unique rotor/geometry are shown at the rotor plane and at tail surfaces) using the thin-layer combination for which conclusions a station on the model support. In Navier-Stokes equations was con- can be drawn only for that particular comparing the streamline results, the ducted using the OVERFLOW code configuration. A generalized method rotor wake for the 0-degree angle of by Pieter Buning of ARC. These for optimizing rotor performance incidence directly interacts with the simulations gave further credence and minimizing fuselage interaction motor assembly. However, at the to the baseline inviscid computa- is not forthcoming. As a result, 15-degree angle of incidence the tions. The combination of complex- numerical methods must be applied rotor wake is completely clear of the geometry/simplified-physics to each configuration to better motor assembly. In comparing the simulations with simplified- identify the aerodynamic effects velocity contours at the rotor plane, geometry/complex-physics simula- of the rotor/fuselage interaction. the contours indicate an interaction tions provided McDonnell Douglas’s The present research was over the motor assembly for the engineers with an overall under- conducted to obtain baseline 0-degree angle of incidence but standing of the Apache flow field interaction results—aerodynamic considerably less interaction at the and with quick feedback on pro- and acoustics data—for the flow 15-degree angle. posed design changes. surrounding the Tilt Rotor Aero- acoustic Model (TRAM) isolated- Point of Contact: P. Stremel Point of Contact: E. Duque rotor configuration. It is extremely (650) 604-4563 (650) 604-4489 important to minimize the interac- [email protected] [email protected] tion of the support hardware with the rotor to insure quality data. However, because of geometric limitations of the support hardware, tunnel installation, and test envelope, a perfectly isolated rotor cannot be tested. The numerical

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Navier-Stokes Simulation lar near-term objective is to predict element edge grids, wake place- the flow about a subsonic transport ment, and wake smoothing strategies of High-Lift Aerodynamics configured for high lift and to assess were developed, verified, and Karlin Roth, Stuart Rogers wind-tunnel interference effects on applied. Importantly, the simulation the flow about this test article. team demonstrated first-of-a-kind The use of the methods of The OVERFLOW code was computations in utilizing a viscous computational fluid dynamics (CFD) used to investigate the flow about a CFD analysis for a complex three- in order to understand the flow over subsonic transport configuration. dimensional high-lift configuration. high-lift wings configured for takeoff The simulations are steady-state, The solution matrix includes a total and landing with leading-edge slats employ the Spalart-Allmaras turbu- of 18 cases which document the and slotted trailing-edge flaps will lence model, and utilize multigrid flow for a range of angles of attack, contribute to the design of simpler or convergence improvement schemes. with and without powered engines, more efficient high-lift systems for The structured, overset grid system and in free-air and within the subsonic transport aircraft. The long- which discretizes the fuselage, high- 12-Foot Pressure Wind Tunnel at range objectives of this work are to lift wing elements, and nacelles Ames Research Center. develop an accurate and efficient consists of 16 million points within Comparison of the free-air and Navier-Stokes analysis method for 36 zones (see figure). During FY96, wind-tunnel simulations shows flow over the high-lift systems of surface grids were generated from significant wall-interference effects subsonic transport aircraft and to the computer-aided design defini- which vary with the model attitude. examine critical physics affecting tion; volume grid methods including In general, simulations conducted in high-lift system design. The particu- the wind tunnel exhibit earlier stall than do the free-air calculations. Further, in addition to an earlier stall angle, powered simulations in the wind tunnel attain lift values near stall which are about 8% higher than the free-air values. In order to test the Wall Interference Correction System developed for the 12-Foot Pressure Wind Tunnel on a powered, high-lift model, it was applied to the simulated data at selected conditions. The initial analysis indicates that this correction method may not be appropriate at conditions near maximum lift.

Point of Contact: K. Roth/S. Rogers (650) 604-6678/4481 [email protected] [email protected]

Fig. 1. Overset grid system within cross section of a multielement high-lift wing.

G LOBAL CIVIL AVIATION / Affordability 37 Lift-Jet Effects on Powered-Lift STOVL Model Karlin Roth

During the transition from hover to wingborne flight, short takeoff and vertical landing (STOVL) aircraft rely on the direct thrust of lift jets to supplement aerodynamic wing lift. The jets usually induce a loss of lift and a change in the nose-up pitching moment on the vehicle; both of these effects increase with increasing forward velocity. Thus, proper design of STOVL aircraft requires an understanding of the physics of the lift-jet/airframe interaction. The ability of three-dimensional, laminar and turbulent Navier-Stokes computations to simulate the Fig. 1. Mach number contours taken in the symmetry plane to illustrate the performance of a geometrically deflection of lift jets. simplified STOVL model during transition flight was investigated. Simulations were made using the leading-edge flow field or the flow Vortex Core Detection OVERFLOW code for the model within 2 diameters of the jet exits. for Computational Grid which consists of a 60-degree For laminar calculations, the pres- cropped delta wing planform; a sure suction peaks at the wing Refinement simple fuselage shape blended to the leading edge tend to be initiated David Kenwright wing; and tandem, circular, high- farther inboard, to cover more area pressure-air lift jets that exit perpen- on the wing, to have slightly less Predicting rotor wake is one of dicularly to the flat lower surface. suction, and to agree better with the the most challenging problems in Predictions were compared with measurements than the turbulent rotorcraft computational fluid measurements at a free-stream Mach predictions. Notably, the simulations dynamics (CFD). The rotor wake is number of 0.146, a 10-degree angle predict a jet-induced lift loss for the disturbed flow that is left behind of attack, and with sonic lift jets. the model that is mostly due to as the rotor blade cuts through the Flow visualization shows the decreased suction at the wing air. The wake rolls up into vortices structure of the wing leading-edge leading edge. near the blade tips, a result of the vortices and the lift jets; the deflec- pressure differences caused by the Point of Contact: K. Roth tion of the lift jets is illustrated in the moving rotor. These vortices, an (650) 604-6678 figure using Mach number contours unwanted side effect of lift, cause [email protected] in the model’s symmetry plane. control buffeting, airframe vibration, Although grid refinements and noise. The requirement for low improve the computational results, noise is particularly important for none of the computations completely characterize the wing

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civilian helicopters and tiltrotors Power Onyx workstation. The same This work is part of an ongoing which operate in highly populated technique has also been applied to computational study of the tip-vortex areas. much larger, unsteady simulations of flow through initial formation/ A major problem with the CFD aircraft to reveal the time-evolution roll-up, growth, and decay. In this simulation of rotorcraft is that the tip of vortex cores. particular study, the near- and vortices diffuse too quickly because intermediate-fields behind the wings Point of Contact: D. Kenwright of inadequate grid resolution. are investigated to (1) explore a (650) 604-1704 Adaptive grid-refinement schemes more physical modeling of the flow [email protected] developed at Ames Research Center by including the viscous upstream have been partially successful in effects; (2) provide an improved capturing these vortices, although vortex flow field to be used as inflow inadequate grid resolution near the for the intermediate-wake; and vortex core causes discrepancies Wingtip Vortex Flows (3) investigate the validity and between computed and wind-tunnel applicability of a simplified Navier- Jennifer Dacles-Mariani, results. Stokes solver using the velocity/ Dochan Kwak A vortex-core detection tech- vorticity formulation in tip-vortex nique was implemented in the The wingtip vortex flow has flow prediction. Unsteady Flow Analysis Toolkit been the subject of numerous The approach taken is to derive (UFAT) to permit scientists to locate studies. Its significance has been a wake model from the full Navier- and visualize the regions of swirling seen in practical problems such as Stokes equations using the velocity/ or rotating flow. This technique is landing separation distances for vorticity formulation. It has the based on an eigenvector method aircraft, blade-vortex interaction, advantage of being able to retain developed at the Massachusetts and cavitation on ship propeller some of the flow physics without a Institute of Technology with funding blades (see first figure). Despite these lot of empiricism. These equations from Ames. The figure (see Color numerous studies, most of the wake- allow physical diffusion in the Plate 6 in the Appendix) shows vortex flow behavior is still not streamwise direction, including vortex cores extracted from a clearly understood. viscous upstream effects and vortex simulation of a helicopter rotor in forward flight. The vortex cores (red lines) become disjointed where the computational grid is too coarse. In this simulation, the grid was refined based on the vorticity magnitude. From the visualization, it is apparent that the grid refinement process failed to capture the vortex core. The vortex cores are extracted in Upwash a batch computation which can take Downwash from seconds to hours to complete depending on the size of the dataset and the complexity of the flow. For the rotorcraft simulation shown in the figure which consisted of Fig. 1. Schematic of a downstream wake of an aircraft. 800,000 tetrahedral elements, the extraction process took less than 8 seconds on a Silicon Graphics

G LOBAL CIVIL AVIATION / Affordability 39 stretching. For vortex-dominated Wind Tunnel at Ames Research Transonic Overset flows, vorticity is the natural choice Center showed a similar trend Potential Solver of variable. The accuracy of the between the measured and the method may be better preserved computed upwash and downwash Terry Holst since it is being calculated directly. velocities (see second figure). The From this study, a detailed slopes of the velocity across the The “full-potential+boundary- account of tip-vortex formation and vortex were predicted well by the layer” approach for transonic cruise of the roll-up process was accom- computation. Most of the disagree- analysis and design can be up to plished. The roles of numerics and ment is in the region where the 100 times faster than Navier-Stokes turbulence models in tip-vortex sampling period of the measured approaches and just as applicable prediction was also studied in detail. data was not long enough, which over a wide range of cases involving The preliminary results indicated resulted in the irregularity of weak shock waves with little or no that the velocity/vorticity formulation the data. boundary-layer separation. A fast using the preconditioned conjugate full-potential capability using a gradient method was successful in Point of Contact: J. Dacles-Mariani zonal grid approach for general predicting wake-vortex flow. Com- (650) 604-5369 geometry modeling will be a valu- parison with measured data of a [email protected] able tool for near real-time assess- 0.03 scale model of the Boeing 747 ment of aerodynamic shapes in the aircraft, taken in the 80- by 120-Foot design or wind-tunnel environments. The objective of the present work is to develop a full-potential analysis and design capability .2 Time averaged value (measured) utilizing the Chimera zonal grid Full Navier-Stokes formulation approach that will be compatible Model II with the well-established .1 OVERFLOW Euler/Navier-Stokes flow solver. Such an approach would be extremely cost effective, 0 especially considering that all of these approaches would utilize the

w-velocity Ð.1 same problem setup and post- processing software, and to a large extent, the same grid-generation Ð.2 software. A transonic three-zone wing- fuselage solver (for inviscid flow) Ð.3 has been developed and validated Ð1.2 Ð.8 Ð.4 0 .4 .8 1.2 using experimental pressure mea- y/b surements (see figure). This half- million-grid-point computation, Fig. 2. Upwash and downwash velocity profile at x/c = 162 feet. which includes surface definition, surface-grid generation, volume-grid generation, Chimera hole-cutting, donor-cell search, flow-field generation, and PLOT3D file generation, required about 1 minute of computer

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time on a single processor Cray C90 1.0 computer. In developing this solver, a new, approximate Chimera donor-cell .5 search algorithm has been developed that is up to 100 times faster than previous techniques. For 0 example, in two-zone cases, the new algorithm can find donor cells

Comp (Y/B=0.17) at a rate in excess of 60,000 cells Ð.5 Comp (Y/B=0.40) per second on a single processor Comp (Y/B=0.85) Cray C90 computer. This search Exp (Y/B=0.17) algorithm has an approximate Pressure coefficient (Ðc) Ð1.0 Exp (Y/B=0.40) characteristic that will automatically Exp (Y/B=0.85) utilize a nearest-neighbor cell when the actual donor cell cannot be Ð1.5 found, thus reducing the chance for Ð.2 0 .2 .4 .6 .8 1 orphan points to exist. Normalized axial distance (x/c) Point of Contact: T. Holst (a) (650) 604-6032 [email protected] .4

.2 Real-Time Particle Tracing

0 in Time-Varying Flows David Kenwright, David Kao

Ð.2 Particle tracing is a scientific visualization technique that is Ð.4 widely used to study aeronautical

Pressure coefficient (Ðc) Comp (fuselage side) simulations. In time-varying flows, Exp (fuselage side) particle tracing can be used to Ð.6 Comp (fuselage top) produce streaklines (a visualization Exp (fuselage top) technique commonly used in wind- Ð.8 tunnel experiments) by simulating 0 .2 .4 .6 .8 1 the continuous injection of particles Normalized axial distance along fuselage (x/l) into a flow. To detect important flow (b) features, several thousand particles must be injected and traced through Fig. 1. Wing/fuselage surface-pressure comparisons RAE wing-fuselage, a flow field by using numerical α ° M∞ = 0.8, = 2 . (a) Upper wing; (b) upper fuselage. integration, which makes particle tracing computationally intensive. Consequently, streaklines are usually pre-computed in a batch process

G LOBAL CIVIL AVIATION / Affordability 41 by using programs, such as the more readily available to research- The implementation of the Unsteady Flow Analysis Toolkit, ers, and by providing quicker Metacenter includes a “peer sched- and then playing them back later in turnaround for batch jobs, a larger uler” to interact with the Portable animations or videos—a process range of available resources for Batch System (PBS) queuing system which can take hours. computation, and better distribution used on each system. In this model, A real-time algorithm for of the computational workload as long as all systems have work to computing and displaying streaklines across multiple supercomputers. do, they act as independent comput- known as the tetrahedra method, The current homogeneous ers. But when the utilization of one was developed by members of the configuration of the Metacenter links system drops below a predefined visualization technologies group the IBM SP2 computers at Ames and utilization threshold, then peer at Ames Research Center. The those at Langley. With the systems scheduling begins. A system that improved performance offered by similarly configured, each Center is short of jobs, “asks” the other the tetrahedra method now allows can rely on help from the other for systems in the Metacenter (its streaklines to be computed and troubleshooting difficult problems. “peers”) for a list of all the queued visualized in real time on high-end Planning and problems are discussed jobs on the remote systems. It then Silicon Graphics, Inc. workstations. at weekly teleconferences, and goes through a series of checks, The benefit to scientists is immediate problems are resolved more quickly verifying that it can indeed run a visualization of their data and the because the experience of personnel specific job. If all the tests are capability to interactively explore at both sites is utilized. passed, the scheduler requests the time-varying flows. Comparisons with conventional particle-tracing algorithms have verified that the NASA MetaCenter FY96 SP2 Utilization tetrahedra method is accurate as Four week floating average, Oct 1, 1995 Ð Oct 1, 1996 well as fast. 100 The tetrahedra method has been Target NAS SP2 installed in two visualization systems LaRC SP2 developed at Ames: the Virtual 80 Windtunnel (see the figure (see Color Plate 7 in the Appendix)) and the Unsteady Flow Analysis Toolkit. 60 Point of Contact: D. Kenwright (650) 604-1704 [email protected] 40

OS upgrage (AIX + PSSP) Available Node Utilization (%) NASA Metacenter 20 Mary Hultquist

0 The NASA Metacenter is an Oct 95 Apr 6 Oct 96 exploratory project of the Parallel Week beginning Systems Groups at Ames Research Center and Langley Research Center. Fig. 1. FY96 utilization on the IBM SP2. The focus of the project is to achieve more effective use of NASA supercomputers by making the systems

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PBS to move the job to the local Eagle is the production super- of growing needs, it is important that server. The job is then run locally, computer for general science and a new source of computing power and the results sent back to the user. engineering research for the Office be found for researchers at Ames This implementation has of Aeronautics and Space Transpor- Research Center. resulted in a more balanced utiliza- tation Technology. Newton is a It was realized that in terms of tion of the Metacenter systems, as testbed supercomputer cluster, raw computer power the Silicon shown in the figure. The users are intended to ease migration of Graphics, Inc. (SGI) workstations thus able to get jobs returned more computer codes between vector sitting on the researchers’ desks, quickly, because a job does not computing and distributed- considered together, had power wait in a queue at one system while computing paradigms. The PBS approximately equal to that of a another system sits idle. Moreover, allows construction of custom four-processor CRAY C-90. Since system downtime is decreased schedulers using any of three this resource was sitting idle every because personnel at both sites can different languages. It is a key night and most weekends, a project work together to get down systems component in NASA’s plan to was undertaken to link these work- back into production. develop metacenters, virtual com- stations, thus creating a cluster puter centers composed of machines computer. Point of Contact: M. Hultquist potentially supplied from several Two needs had to be met to (650) 604-0814 vendors, and potentially sited in make this a reality. One was for fast [email protected] several locations. interprocessor communication. A The PBS beta program ended Grand Junction fast Ethernet data the fiscal year with 51 client sites, switch was obtained, and the distributed among government, 24␣ most powerful of the approxi- Portable Batch System universities, and private industry. mately 60 workstations in use were installed on the data switch. It is David Tweten Point of Contact: D. Tweten expected that this switch will at least (650) 604-4416 double the interprocessor communi- As of this year, all super- [email protected] computers at Ames Research Center, cation speed for these workstations whether production or testbed, and by eliminating “data collisions” at a regardless of manufacture, run the local network router. same batch and cluster control The second need was for system, the Portable Batch System Developing a Cluster scheduling software to queue jobs, (PBS). Most recently, Ames’s two Computer from oversee their execution, and gener- Cray C-90s, called the vonNeumann ally make the workstations function and Eagle, as well as the Center’s Workstations together as a computer. The Portable Cray J-90 cluster, called the Newton, Reese L. Sorenson Batch System (PBS) software, were converted to use the PBS as developed locally at Ames and their sole production batch system. Finding adequate computational already functioning as the operating The PBS is a research batch process- resources to meet the ever-expanding system on a CRAY supercomputer ing and cluster control software needs of aerodynamic simulation by and on a dedicated workstation package written at the Center. computational fluid dynamics (CFD) cluster, was ported to these VonNeumann is NASA’s largest has always been a challenge, one machines and customized for this supercomputer; it is used to perform exacerbated by recent budgetary implementation. cutting-edge research for NASA’s constraints and redirected priorities. The cluster is scheduled to be aeronautics-focused programs and Facing a possible decrease of available 12 hours per day through- for base research and technology. available computer time in the face out the year. Test cases have been run successfully on it. Recently

G LOBAL CIVIL AVIATION / Affordability 43 acquired workstations, even more without quantitative comparison shifts and with computed scattering powerful than those originally used, with other measurements, or in signals using a Mie scattering theory are being installed in the cluster. supersonic flows where the Doppler for polydisperse smoke particles. The Documentation to be posted on the shift is large and its measurement is relevant parameters incorporated a World Wide Web has been written. relatively insensitive to instrumental range of practical aerodynamic test The significance of this project errors. Moreover, most reported conditions and facility sizes. The is twofold: first, the critically impor- applications have relied on the use results (1) helped define the opti- tant work of aerodynamic simulation of continuous-wave lasers, which mum values of the instrument at Ames will continue to have limit the measurement to time- parameters, (2) showed that the adequate computational resources; averaged velocity fields. expected signal levels from a second, the software techniques and The objective of this study has practical PDV system were suffi- the experience of this project are been to quantitatively determine the ciently large to allow its useful available to others facing similar limits of PDV capabilities for appli- application in large facilities, and constraints. cations in large-scale wind tunnels (3) showed that the expected that are intended primarily for velocity measurement uncertainties Point of Contact: R. Sorenson production testing of subsonic were small relative to the mean (650) 604-4471 aircraft. For such applications, the velocities of interest for most sub- [email protected] adequate resolution of low-speed sonic, large-scale wind-tunnel flow fields requires accurate mea- testing. surements of small Doppler shifts PDV performance was then that are obtained at distances of demonstrated by using several Planar Doppler several meters from the sample bench-top setups, including a Velocimetry Using region. In addition, the use of rotating wheel where the exact pulsed lasers provides the unique velocity field was always known Pulsed Lasers capability to obtain not only time- everywhere, a turbulent air jet with Robert L. McKenzie averaged fields, but also their flow properties that were calibrated statistical fluctuation amplitudes and using pitot and hot-wire probes, Recently, planar doppler the spatial excursions of unsteady and stationary solid and aerosol velocimetry (PDV) has been shown flow regions such as wakes and targets where only the PDV noise is by several laboratories to offer an separations. observed. Images from these targets attractive means for measuring three- To accomplish the objectives, were used to validate the model dimensional velocity vectors every- the PDV measurement process was description of noise magnitudes and where in a light sheet placed in a first modeled and its performance to confirm the minimum velocities flow. Unlike other optical means of evaluated computationally. The that could be resolved. The bench- measuring flow velocities, PDV is noise sources considered included top experiments also allowed the particularly attractive for use in large those related to the optical and optical configuration and calibration wind tunnels where distances to the electronic properties of charge- procedures of the instrument to be sample region may be several coupled device (CCD) arrays and developed into a robust and easily meters, because it does not require to speckle effects associated with operated system that is applicable to the spatial resolution and tracking of coherent illumination from pulsed the environment of large-scale wind individual scattering-particles or the lasers. The signal-noise estimates tunnels. An example of some results alignment of crossed beams at large were incorporated into the PDV is shown in the figure (see Color distances. To date, demonstrations signal analysis process and com- Plate 8 in the Appendix) where the of PDV (called “doppler global bined with a spectroscopic model average axial velocity field and its velocimetry” by some authors) have of the iodine vapor cell used to root-mean-square fluctuation been made either in low-speed flows discriminate Doppler frequency amplitudes are displayed for the flow in a low-speed, turbulent, free jet.

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The plane of the image is normal to not follow the sudden changes in ses. Before these more powerful the jet centerline. The velocity flow speeds or directions. The methods can be of practical value to profiles are taken along the grid lines method has further advantages: aircraft designers, however, they shown in each image. The velocity the measurement procedures are must be tested by comparing their field, part (a) in the figure, shows the compatible with the production results with reliable experimental average velocity distribution of the testing environment of large-scale data. In particular, it is important to core flow and the fluctuation field; wind tunnels, the experimental setup verify that unsteady, nonlinear part (b) of the figure shows the high is relatively simple, and the system aerodynamic features and their relative fluctuation amplitudes in the could be operated by trained wind- interactions with the structure are turbulent shear layer at the edge of tunnel technicians as a production properly represented. the jet. These measurements were instrument. To help address this need, made with a preliminary PDV simple, small-scale, aeroelastic Point of Contact: R. McKenzie optical system that was capable of experiments were conducted in the (650) 604-6158 determining only one velocity High Reynolds Number Channel 2 [email protected] component. The combined use of (HRC-2) at Ames Research Center. two additional systems would allow The objective of the experiments the determination of all three was to (1) evaluate the use of velocity components simultaneously pressure-sensitive paint (PSP) to from each laser pulse. Pressure-Sensitive Paint measure unsteady pressure distribu- The PDV measurement capabili- and Photogrammetry for tions on aeroelastic models and ties developed in this study demon- (2) stereophotogrammetry to mea- strate that PDV offers significant Aeroelastic Experiments sure unsteady model deformations. advantages when compared with Edward T. Schairer, Semispan, clipped delta-wing other means of measuring velocity Lawrence A. Hand models built from thin flat plates fields in large-scale, subsonic wind were tested at transonic speeds. tunnels. Measurements obtained Methods for predicting the The models were imaged by three from each laser pulse allow the aeroelastic stability of aerospace synchronized black-and-white video accurate resolution of complete structures are generally based on cameras, and the data were recorded velocity vector fields with resolu- linearized aerodynamic theory. The on videotape. Correlated images tions of instantaneous speeds as low accuracy of these methods suffers from two of these cameras were as 2 m/sec. Much smaller average when nonlinear flow features (for used to estimate the space coordi- speeds can also be resolved. From example, shock waves, vortices, nates of reference marks on the the pulse-to-pulse data, both mean separated flow) interact with the model at each instant, and the velocities and their fluctuation aircraft structure. For example, at motion of each mark was estimated amplitudes can be determined in transonic speeds, where significant by fitting the deflection data with a any aerosol-seeded flow with shock waves may be present, two- damped sinusoid. The third camera adequate optical access, including and three-dimensional wings tend to was used for PSP. complex, three-dimensional, turbu- flutter at lower dynamic pressures All the procedures needed to lent flows. The method has no upper than predicted by linear flutter measure unsteady pressure distribu- limit above which velocity can not analyses. tions using PSP were successfully be measured, other than in extreme Since the late 1970s, consider- demonstrated. The PSP measure- hypersonic flow situations contain- able progress has been made in ments were seriously compromised, ing strong shock waves; in the latter using computational fluid dynamics however, because the response time case, the necessary scattering (CFD) to account for nonlinear of the pressure paint was too slow, particles or aerosols in the flow do aerodynamics in aeroelastic analy- resulting in significant attenuation

G LOBAL CIVIL AVIATION / Affordability 45 of the unsteady component of the PSP signal. The first figure presents typical PSP data from a run (Mach = 0.85), where the wingtip was deflected and released. The gray levels in the image (part (a)) which was acquired just after the wingtip was released, are proportional to the pressure coefficient. Part (b) of the figure compares the pressure coefficient along a spanwise line from root to tip with steady data acquired after the unsteady transient had disappeared. Note that the suction peak associated with the leading-edge vortex has moved outboard in the steady condition. The second figure presents photogrammetry data acquired during a run at Mach = 0.85, where the tip of the model was unre- strained as the pressure in the tunnel was slowly increased. Part (a) of the (a) figure shows the time history of the deflection of the wingtip at three 1.0 dynamic pressures just before the model became unstable; part (b) shows the phases and amplitudes of .8 points on the wing compared with Steady the trailing edge of the wingtip. The (final) onset of instability was marked by a .6 Unsteady large increase in the amplitude of p the motion, as well as an increase in ÐC the phase difference between the .4 leading and trailing edges. This work is a first step in using PSP and photogrammetry to docu- .2 ment complex, unsteady aeroelastic responses. Once these techniques 0 are further refined, they can be used 0 .2 .4 .6 .8 1.0 to better understand these responses y/b and to help validate higher-order aeroelasticity methods. A natural (b)

Fig. 1. PSP image of flexible wing and corresponding pressure coefficient along x/C = 0.75.

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Tip deflectionPhase difference (deg) Amplitude ratio .6 .90 .4 .80 q = 3.33 .70 .2 .50 .60 0 .30 .40 z/b 0 .20 Ð.2 20 10 .10 Ð.4 f = 48.4 Hz; ζ = Ð0.0004 Ð.6 .6 .90 .4 .70 .80 q = 3.45 .50 .2 .60 .30 0 .40 z/b 10 .10 .20 Ð.2 20 0 Ð.4 f = 50.3 Hz; ζ = 0 Ð.6 .6 .4 .90 .70 .80 q = 3.47 .50 .2 10 .60 .30 0 30 .40 z/b 40 .10 Ð.2 60 70 50 .20 90 20 Ð.4 100 80 f = 51.2 Hz; ζ = Ð0.0014 Ð.6 0 .10 .20 .30 .40 Time (sec) (a)␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣␣(b)

Fig. 2. Deflection of wingtip trailing edge, and phase difference and amplitude ratio with respect to tip trailing edge. extension of this work is to apply Visualizing Wind-Tunnel ing computational results to be PSP and photogrammetry to tests of Experimental Data applied to experimentally collected helicopter rotor blades. data. This product is a step toward Samuel P. Uselton, Glenn Deardorff, developing a unified environment Point of Contact: E. Schairer/L. Hand Leslie Keely, Yinsyi Hung, Arsi Vaziri for analyzing data from multiple (650) 604-6925/1646 sources. The ability of researchers [email protected] A new software tool that dis- and engineers to display and interact [email protected] plays data collected during wind- with data from a variety of sources tunnel tests and that supports within a single visualization environ- interactive analysis of those data has ment will increase the understanding been developed at Ames Research gained from the data and reduce the Center. The tool, called exVis, time required. allows visualization and interaction The initial product, exVis 1.0, methods frequently used in analyz- was developed for data collected

G LOBAL CIVIL AVIATION / Affordability 47 using a pressure-sensitive paint (PSP) Previously selected slices or graphs Surface Tension Effects system. The exVis software package can be deleted, and a graph can be reads a Flexible Image Transport printed via postscript. A user can on Skin Friction System (FITS) format file produced save the current status and restore Measurements by the PSP data-acquisition system the program to that state at a later G. Zilliac, A. Celic which contains pressure values, and time. An on-line help feature is also displays these data as an image in a included. The Fringe-Imaging skin friction window (“ImageViewer” shown at Although exVis was developed technique (FISF), which was origi- left in the figure (see Color Plate 9 in specifically with PSP data acquisi- nally developed by Monson and the Appendix)). The image can be tion in mind, it is sufficiently robust Mateer at Ames Research Center displayed using a gray scale or a to work with other scalar data that and recently extended to three- pseudocolor mapping of data to are provided in FITS format, and dimensional flows, is the most screen intensity. could be easily adapted for data accurate skin-friction measurement Users can select tools that allow provided in other two-dimensional technique currently available. The the selection of a “slice” of data from array formats. ExVis 1.0 was com- principle of the FISF is that the the image along a line segment. This pleted in July 1996 and integrated skin friction at a point on an aero- slice is then graphed in a separate with other Ames-developed dynamic surface can be determined window (“GraphViewer,” at the right software for use in a wind-tunnel by measuring the time-rate-of- in the figure) that shows how the test (September 1996). change of the thickness of an oil coefficient of pressure varies along drop placed on the surface under the Point of Contact: S. Uselton the length of the slice. Several slices influence of the external air bound- (650) 604-3985 can be selected from the same image ary layer. Lubrication theory is used [email protected] and graphed on the same axes, or to relate the variation in oil-patch different slices (or sets of slices) can thickness to shear stress. be graphed in separate windows. Multiple ImageViewers can each display an image, with selected .2 slices graphed together or separately. The ImageViewer and GraphViewer 3 sec 4 sec can each be queried interactively .1 2 sec 1 sec to show the data value at the Y, mm 0 sec cursor; the GraphViewer also 0 displays the corresponding location 0 1 2 345678 in the ImageViewer. The user can X, mm change the sizes and positions of ImageViewers and GraphViewers. Fig. 1. Oil-drop profile evolution.

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.1 RIPPLE result Fullerene Gear Design, Simplified model Simulation, and Visualization Albert Globus

H, mm Ames Research Center has designed and computationally investigated a series of atomically precise gears based on fullerene chemistry (see first figure). These gears are approximately 1 nanom- .01 .001 .01 .1 1 10 eter in diameter and can turn at up to 100 gigahertz according to T, sec computer simulations. Long-range Fig. 2. Oil-drop thickness at X = 3 mm. goals include the design and validation of programmable molecular machines that can replicate and build useful aerospace products. The uncertainty of FISF measure- from its initial circular-arc shape to a This work will require massive ments is estimated to be as low as wedge-like shape. The close agree- computer power as nanotechnology 4%, yet little is known about the ment between the oil-drop thickness research moves from “what if” to effects of surface tension and wall- computed using RIPPLE and the “how.” The current simulations help adhesion forces on the measured results obtained with a greatly in understanding these computa- results. simplified numerical model of oil- tional requirements. If successful, A modified version of the free- drop flow (solution of Squires oil- molecular nanotechnology could surface Navier-Stokes solver RIPPLE, drop equation which does not revolutionize aeronautics and space developed at Los Alamos National include surface tension and wall- technology by producing materials Laboratories, was used to compute adhesion effects) proves that surface with radically improved strength-to- the time development of an oil drop tension will have a negligible effect weight ratios and active materials on a surface under a simulated air on FISF results (second figure). filled with atomically precise boundary layer. RIPPLE uses the Point of Contact: G. Zilliac machines that react to the environ- Volume of Fluid (VOF) method to (650) 604-3904 ment and that can self-repair. track the surface and the Continuum [email protected] Hypothetical nanotechnology Surface Force (CSF) approach to materials based on diamond chemis- model surface tension and wall- try have great potential, but at adhesion effects. present no clear path can be seen for The figures show the develop- their synthesis. In contrast, fullerenes ment of an oil drop over a period of (closed-cage carbon molecules) are about 4 seconds. The profile of the now routinely produced in the drop (first figure) rapidly changes

G LOBAL CIVIL AVIATION / Affordability 49 laboratory. The carbon form called C-60 (a molecule with 60 carbons arranged in a soccer-ball-like configuration) is produced commer- cially, and carbon nanotubes have been produced in bulk, some over 100 microns long. It is possible to add a wide variety of molecular fragments to C-60 and other fullerenes. In particular, benzyne will react with the C-60 under mild laboratory conditions to form appended structures similar to gear teeth. A series of videos has been made including gear synthesis steps, favorable operating conditions, various gear configurations, a rack- and-pinion system (see second figure), and tooth slip conditions, which are all based on molecular dynamics simulations run on parallel Fig. 1. Hypothetical carbon nanotube gears. Each gear is approximately computers. Each gear consists of a 1␣ nanometer in diameter. Simulations suggest this system can rotate at up carbon nanotube with several to 100 gigahertz. O-benzyne fragments added to form gear teeth. Molecular dynamics simulations suggest that when one gear is rotated, intermolecular forces cause the second gear to rotate at up to 100 gigahertz without slippage or fragmentation.

Point of Contact: A. Globus (650) 604-4404 [email protected]

Fig. 2. Hypothetical rack-and-pinion system built from functionalized fullerene nanotubes.

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GGLOBALLOBAL C CIVILIVIL A AVIATIONVIATION/ / Nacelle deceleration 110/60 NVIRONMENTAL OMPATIBILITY 140/30 180/0 <- 250/0 ENVIRONMENTALE C COMPATIBILITY for landing from Landing Decision Point at 200 ft altitude 2000 ft altitude Civil Tiltrotor Noise 3° initial Abatement Approaches glideslope ° William A. Decker, 9 final 250/0 glideslope Rickey C. Simmons 180/0 140/30 A civil tiltrotor regional transport 3000 ft altitude operating from vertiports near urban 110/60 and business centers offers consider- 3° able potential for relieving conventional airport runway congestion. Flight operations near urban areas 9° must also minimize noise effects while providing for all-weather schedule reliability. Conversion from Fig. 1. Tiltrotor noise-abatement approach profiles with two-segment airplane-mode flight to a helicopter- flightpaths. Altitude (flightpath angle), airspeed, and nacelle angle (for ° like landing while minimizing noise example, 110/60 ) are specified as functions of distance from landing. presents both a challenge and an opportunity for tiltrotor aircraft. The introduction of worldwide aircraft the vertiport. Depending on the electronic display formats for position information with the Global terrain and airspace constraints transport aircraft. Pursuit guidance Positioning Satellite system provides associated with nearby conventional using flightpath vector symbols, an economic guidance source to airports, the initial approach seg- adapted from military head-up support the desired low-noise, ment involved conducting either a display designs, has been developed all-weather operations. level-flight conversion toward the for tiltrotor use and applied to the Initial tiltrotor noise-abatement helicopter-mode landing configura- panel-mounted electronic displays. landing approach profiles were tion, or performing all of the conver- The unique large-motion cueing constructed based on actual noise sion in descending flight. Both capability of the Vertical Motion measurements of the XV-15 tiltrotor approach profiles carefully specified Simulator (VMS) at Ames Research research aircraft. Instead of a airspeed, descent rate (flightpath Center contributed to piloted conventional landing approach position) and proprotor tilt angle evaluations of approach profiles which intercepts and tracks down a based on the distance from the and displays. Use of a visual scene 3-degree glideslope, two alternative landing spot. based on the San Francisco Bay profiles were constructed, both Cockpit displays and control Area, developed in the VMS featuring an initial 3-degree descent features have been developed to SIMLAB, contributed to the evalua- which changes to a steep 9-degree help guide pilots to reliably and tion scenario and provided geo- descent close to the landing spot easily fly these complex approach graphic rationale for the complex (first figure). Based on the XV-15 profiles in all-weather conditions. As approach flightpath. Eleven pilots noise data, the steeper final illustrated in the second figure, the representing NASA, the FAA, British approach path offers good potential displays were adapted from modern CAA, and the rotorcraft industry for reducing noise while providing better clearance of obstacles near

G LOBAL CIVIL AVIATION / Environmental Compatibility 51 phone to measure BVI noise generated by the XV-15 tiltrotor. Four flights were performed with the YO-3A and XV-15 flying in close formation, as shown in the figure. The flight conditions and microphone location were chosen to measure the most prominent BVI noise. The starboard wing-tip microphone of the YO-3A was positioned 20 degrees below the right rotor hub of the XV-15 and offset to the right to pick up BVIs occurring at a rotor azimuth of 150 degrees (see figure). The distance between the starboard wingtip microphone and the rotor hub Fig. 2. Pilot’s view on approach to urban vertiport. Electronic cockpit was 3 rotor diameters (75 feet). displays provide guidance for complex noise-abatement approach profiles. Target flight conditions included advance ratios of 0.165 and 0.185, tip Mach number of 0.69, a rotor evaluated the approaches and sons with similar wind-tunnel weight coefficient of 0.0111, and displays, and provided comments measurements, (2) to use these descent rates of 300–1100 feet per for further refinement. comparisons to better understand minute. BVI noise, and (3) to determine how The results of the flight test were Point of Contact: W. Decker to minimize BVI noise on rotorcraft. used to determine equivalent test (650) 604-5362 During the flight portion of this conditions for a series of tests of the [email protected] test, the YO-3A fixed-wing aircraft XV-15 rotor in the National Full- used a wing-tip-mounted micro- Scale Aerodynamics Complex

XV-15 Blade-Vortex Interaction Noise C. W. Acree, Megan S. McCluer, Cahit Kitaplioglu

As part of the continuing In-Flight Rotorcraft Acoustics Program, flight tests of the XV-15 tiltrotor were completed and wind- tunnel tests are under way. Program objectives are (1) to use the NASA Ames YO-3A acoustic research aircraft to measure blade-vortex interaction (BVI) noise from rotorcraft in flight and to make compari- Fig. 1. YO-3A and XV-15 in formation flight.

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(NFAC) 80- by 120-Foot Wind improved understanding of the ducted in the NFAC N246 Model Tunnel test section at Ames Research aeroacoustic characteristics of Preparation building at Ames. Center. A single (right-side) rotor was tiltrotor aircraft and, therefore, The checkout testing included the mounted on the Rotor Test Appara- initiated the development of two acquisition of hover data—including tus (RTA), and microphones were hardware-compatible test rigs: an rotor airloads data—for a 1/4-scale placed in locations geometrically isolated-rotor test stand and a full- set of proprotor blades using the identical to the relative positions of span model (dual rotors with a NFAC NPRIME data-acquisition the YO-3A microphones and XV-15 complete airframe representation). system. Key test-stand capabilities rotor during flight. The data from the These two test stands are inclusively being checked out include a rotating NFAC tests have been compared called the Tilt Rotor Aeroacoustic amplifier system (RAS) developed with the flight data to validate the Model (TRAM). The isolated rotor by the Nationaal Lucht-en wind-tunnel test and the measure- test stand is not a stand-alone unit, Ruimtevaartlaboratorium (NLR) ment methods. Although very good but is instead intended to be com- and the Monitoring Front-End Data qualitative agreement was achieved, posed chiefly of major subassem- System (MFEDS) real-time safety- good quantitative agreement has yet blies of the full-span configuration. of-flight monitoring system. A to be demonstrated. In particular, the The TRAM will be used as a test considerable amount of infrastruc- ability to match wind tunnel with bed for testing moderate-scale tilt- ture buildup—including armor-plate flight will likely require very good rotor models in two different test shielding and control room installa- characterization of the flight operat- configurations in different research tion—was required in the N246 ing conditions to enable matching of facilities: (1) isolated rotor testing at building to enable TRAM functional the exact test condition in the wind the Duits-Netherlands Windkannal testing. tunnel. (DNW) in The Netherlands; and The full-span version of the (2) isolated rotor and full-span TRAM test stand is also being Point of Contact: C. Acree testing at the National Full-Scale concurrently developed. Fabrication (650) 604-5423 Aerodynamics Complex (NFAC) at of full-span model development is [email protected] Ames Research Center. under way (see figure). A new A checkout test of the TRAM generation rotor-control console for isolated-rotor test stand was con- Tiltrotor Aeroacoustic Model Larry Young

NASA conducts tiltrotor research programs in order to meet national requirements for military and civilian tiltrotor aircraft. This research requires moderate-to-large- scale wind-tunnel testing of tiltrotor models. Such testing provides the data necessary to confirm aeroacoustic prediction methods, and to investigate and demonstrate advanced civil tiltrotor and high- speed rotorcraft technologies. In 1991, NASA established that Fig. 1. Full-span TRAM fabrication and assembly. it had a requirement to gain an

G LOBAL CIVIL AVIATION / Environmental Compatibility 53 the isolated rotor test and the full- to analyze those predictions in a acoustic propagation allows rotor span model is also in development. way that identifies the sources of the designers to “see and hear” the noise The 1/4-scale TRAM rotors and offending noise; and (3) control of in the far-field. Computer animations airframe are based on the design of rotor-blade motion in ways that of the far-field noise propagation the V-22 Osprey tiltrotor aircraft. reduce the noise. Researchers at convey much more information than The TRAM test stand will also be an Ames Research Center have recently can be obtained from typical rotor- advanced technology demonstrator developed new acoustic prediction noise experiments, in which the platform for the Short Haul Civil and analysis tools that directly data are limited to those picked Tiltrotor (SH(CT)) program, a sub- address the first two of these three up by a few far-field microphones. element of the Advanced Subsonic objectives. In addition to the new prediction Technology (AST) initiative. Both The new acoustic prediction and visualization tools, the CFD/ Boeing and Sikorsky Aircraft have scheme combines computational Kirchhoff analysis can be modified been contracted by the NASA fluid dynamics (CFD) with Kirchhoff to highlight the sources of noise on SH(CT) program to develop interface integration methods. The CFD the Kirchhoff surface. This allows a hardware to test a new generation of methods compute the nonlinear rotor designer to pinpoint the origins small-scale, advanced proprotors on aerodynamics and acoustics close to of the far-field noise and to modify the TRAM test stand. the rotor blades, and the Kirchhoff the blade trajectories to minimize integrations carry the acoustic the blade-vortex interactions. Point of Contact: L. Young information to the far-field in a The new prediction and analysis (650) 604-4022 computationally efficient manner. tools will have applications to a [email protected] These CFD/Kirchhoff methods run variety of helicopter and tiltrotor on the IBM SP-2 parallel computer geometries. to facilitate the computation of time- Point of Contact: R. Strawn accurate acoustic information over (650) 604-4510 Predicting and Analyzing large regions of space. Computer [email protected] Rotorcraft Noise audio and visual rendering (see figure) of the resulting far-field Roger C. Strawn, Rupak Biswas, Lenny Oliker

Aerodynamic noise is a major problem for future civil tiltrotor designs. Noise is a particular problem during landing when the rotor- wake system is pushed up into the rotating blades. The resulting blade- vortex interaction (BVI) noise can be unacceptable in urban environments. All four of the major U.S. helicopter companies have active research programs with the objective of reducing tiltrotor and helicopter BVI noise. Three things are required in order for rotor designers to systematically reduce BVI noise: (1) an improvement in the accuracy of far- field noise predictions; (2) the ability Fig. 1. Computed acoustic pressure contours for the AH-1 Cobra helicopter.

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Airframe Noise Measurements: Atmospheric Pressure W. Clifton Horne, Julie A. Hayes, Michael E. Watts, Paul H. Bent

With the trend toward quieter, higher bypass-ratio engines in commercial transport aircraft, airframe noise is a significant problem during approach and landing. In support of the Noise Reduction Element of the Advanced Subsonic Technology (AST) Program, an aeroacoustic test of an unpowered, 4.7%-scale McDonnell Douglas DC-10 was conducted in the NASA Ames 40- by 80- Foot Wind Tunnel (see figure). Acoustical measurements included streamwise traverses of four microphones, far- field measurements with directional microphones using parabolic reflectors, and noise-source location with a 40-element phased microphone array. Aerodynamic measurements included steady and unsteady wing-surface pressures and model incidence. The primary objectives of this test were to (1) assess the feasibility of extrapolating wind-tunnel airframe noise measurements for Fig. 1. DC-10 model in the Ames 40- by 80-Foot Wind Tunnel. comparison with full-scale flight-test results, (2) locate prominent noise Processing System developed at as 3 months of posttest processing sources with the acoustic array, Ames Research Center. were required in previous tests). The and (3) evaluate prototype noise- This system used high-performance processing system was designed to reduction concepts on a realistic graphical workstations in the control fully support existing remote access transport configuration. room to process the array data and wind-tunnel capabilities. Measurements supporting all display results during the test. The Studies of flap-edge fences of the primary test objectives were system processed 200 frequencies at designed to reduce noise emanating obtained. In particular, acoustic each data point within 30 minutes, from the flap edge showed broad- images of airframe noise sources on thus allowing all test data to be band noise reduction levels of the high-lift system and landing gear processed during the test (as much were obtained. This was achieved using the Microphone Array Phased

G LOBAL CIVIL AVIATION / Environmental Compatibility 55 3–4 decibels. Correlation of the well understood. Therefore, acoustic accommodated with existing facility noise signals on a far-field micro- measurements, over a range of scale support infrastructure. Several phone with the unsteady pressure factors (or Reynolds numbers), are aeroacoustic noise sources were signals on the model aircraft surface required to identify the important located with the array, associated was effective in locating the source noise sources on full-scale aircraft with support struts and the trailing of the airframe noise. and to determine the scaling laws edge of the semi-span ground that will permit accurate full-scale plane. The second test utilizing the Point of Contact: C. Horne predictions from small-scale tests. 4.7%-scale DC-10 aircraft model (650) 604-4571 Recent successful tests by Ames was then undertaken. During this [email protected] and Boeing using a multielement second test, the Boeing array phased microphone array in closed, acquired noise measurements to untreated test sections suggested that 60␣ kilohertz, corresponding to about useful airframe noise measurements 3 kilohertz full-scale, and identified Airframe Noise could be obtained in the Ames noise sources at atmospheric Measurements: Pressures 12-Foot Pressure Wind Tunnel pressure which corresponded (PWT) for variable Reynolds number closely with sources identified in to 4.7 Atmospheres testing. Feasibility tests of a Boeing the previous 40- by 80-Foot Wind W. Clifton Horne, Stephen M. Jaeger, 52-element array in the 12-Foot Tunnel test (see figure (see Color Mahendra Joshi, James R. Underbrink PWT were planned in two phases. Plate 10 in the Appendix)). In An initial study of the operational addition, noise measurements Airframe noise, primarily feasibility was planned with the test were obtained for pressures up to attributable to the landing gear, section empty except for a survey 4.7 atmospheres. Preliminary leading-edge slat, and trailing-edge strut, model ground plane, and evaluation of these measurements flap, is known to be a significant calibration noise sources. If this show that the relative strength of the component of the approach and initial study proved to be successful, noise sources varies with Reynolds landing noise of commercial trans- a second demonstration of aero- number in a complex and as yet port aircraft. The NASA Advanced acoustic measurements of a unpredictable manner, stressing Subsonic Technology (AST) Noise 4.7%-scale DC-10 was planned in the need for large-scale, high- Reduction Technology Program is conjunction with McDonnell Reynolds-number validation of sponsoring several measurement and Douglas to acquire the first variable noise-prediction methods. prediction programs in order to Reynolds number airframe noise Point of Contact: C. Horne reduce airframe noise by 4 decibels measurements. The results would be (650) 604-4571 below 1992 levels. Because of the compared with atmospheric mea- [email protected] expense of flight tests, an important surements acquired from the same element of this research is the model in the 40- by 80-Foot Wind application of new measurement Tunnel at Ames with a 40-element technology, such as the multisensor phased-array designed and phased acoustic array, on tests of assembled at Ames. small-scale wind-tunnel models and The first feasibility test demon- then scaling and extrapolating these strated that the microphone-array measurements to full-scale. The system (sensors, cabling, signal physics of aerodynamic noise acquisition and processing, and generation and the effect of geomet- computer networking) could be ric scale are highly complex and not

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R REVOLUTIONARYEVOLUTIONARY TTECHNOLOGYECHNOLOGY LLEAPSEAPS// The project involves the design, Closed-Loop Neural ␣␣IINNOVATIVENNOVATIVE TTECHNOLOGY ANDAND TTOOLSOOLS fabrication, and flight evaluation of two unmanned aircraft. The 10-foot- Control of Rotorcraft span flight articles are about 18 feet Vibration long and 3 feet high and weigh Sesi Kottapalli X-36 Pioneers Advanced 1250 pounds. Aerodynamics and Flight Features of the X-36 include A study on identification and multifunction wing trailing edge control of rotorcraft hub loads Controls control surfaces, combined ailerons, (vibration) using neural networks Rodney Bailey, Mark Sumich split ailerons and flaps, wing leading has been initiated at Ames Research edge flaps, and all moving canards. Center. Neural control simulation The X-36 project is pioneering The aircraft has neither vertical nor covers both identification and the development of advanced horizontal aft tail surfaces. The control of hub loads, where a metric aerodynamics and flight control aircraft (shown in the figure) is is used to represent the hub load technologies that will permit the naturally unstable in both the pitch components. The closed-loop concurrence of low radar observa- and yaw directions, with artificial controller must be computationally bility, agility, and supersonic speed stability provided by the control laws efficient, it must converge quickly in a single design. Prior to the X-36 utilizing both aerodynamic and (in six iterations or less), and technologies, these features were propulsion forces. gradient-based methods must mutually exclusive. The flight The flight testing at Dryden will not be used. evaluations of the X-36 aircraft, a evaluate real-time stability margin The program objective is to joint NASA/McDonnell Douglas and will determine aerodynamic, implement closed-loop neural project, are currently under way at stability, and control data on the control of rotorcraft vibration in the Dryden Flight Research Center. configuration using the parameter- a wind tunnel in two phases: The project began in February identification derivative. (1) conducting neural-control 1994 after several years of research simulations using existing individual Point of Contact: R. Bailey and concept development in the blade-control wind-tunnel test data, (650) 604-6265 Ames facilities by both Ames and and (2) implementing closed-loop [email protected] McDonnell Douglas engineers. neural control during a future full- scale rotorcraft wind-tunnel test (contingent on first-phase results being sufficiently promising). The identification (plant modeling) procedure, which involves the use of a two-hidden-layer radial basis function neural network, has been completed. The procedure has been extended to multi-input, multi- output applications. A simple, straightforward-to-implement neural- control technique, the “direct inverse” method, was selected, successfully applied, and found to Fig. 1. X-36 Tailless Fighter Agility Research Aircraft prepares for flight at the Dryden Flight Research Center.

R EVOLUTIONARY TECHNOLOGY LEAPS / Innovative Technology and Tools 57 modules to the code OVERFLOW. Present Closed Loop Neural Control Simulation The object is to demonstrate the use (“metric” refers to vibratory hub loads metric) of a numerical-optimization routine

Control Actual Desired Updated to understand the significance of phase input metric metric control phase different geometric parameters on input the aerodynamics of a wing. This study demonstrated how Inverted one optimizer package is used to Half-interval neural network Plant method study the flow physics of a transonic for control model (user specified (supplies new wing. This numerical-optimization metric reduction) control input) routine is integrated with a grid generator and a validated Navier– Stokes flow solver. The effects of wing sweep angle, root and tip twist Fig. 1. Inverted neural network for vibration control. angles, dihedral, and angle of attack on the lift-to-drag ratio are studied using surface-pressure contours and be robust. The present approach (see Coupled Navier–Stokes pressure distributions. The results show that when lift-to-drag ratio the figure) has the following essential and Optimizer Analysis ingredients: accurate plant model- is increased using single design ing, halving of the metric in order to of a Transonic Wing variable optimization, the resulting lift coefficient falls below the accelerate controller convergence, Roxana M. Greenman, original value. The angle of attack “inverted-axes” control modeling, Samson Cheung, Eugene L. Tu and a feedback iterative loop. A must be increased in order to back-propagation neural network Numerical optimization can be preserve the original lift coefficient used in the control step has been used as a means of studying the with the modified geometry. A better successful. Current results show that effects of the geometric parameters way to find the optimal configura- a 66% reduction in baseline rotor on the aerodynamics of a wing. tion with the highest lift-to-drag ratio vibratory hub loads is achievable in Different types of aerodynamic is by first optimizing with multiple only four controller iterations. A numerical-optimization techniques design variables (see the figure (see limited-scope comparison of the that have been researched in recent Color Plate 11 in the Appendix)), results from the present neural- years have been found to need then including the angle of attack in control procedure with those from improvement. New optimization the design loop with lift constrained a one-step deterministic controller tools must be developed to provide to the original value. This method showed that the two control meth- efficient means for improving the showed an improvement of 2.4% ods are comparable, with neural design process and understanding (with constant lift) in the lift-to-drag control being more robust. the flow physics. The overall objec- ratio. tive is to develop the necessary tools Point of Contact: S. Kottapalli Point of Contact: R. Greenman needed to help, using computational (650) 604-3092 (650) 604-3997 fluid dynamics for the design of [email protected] [email protected] advanced wings through the inclusion of new, promising optimization

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Parallel Unstructured be modified can be rapidly identified These improvements are necessary when an edge is inserted or deleted. for future high-fidelity simulations of Mesh Adaption Regions of the mesh that need to be realistic problems in unsteady Rupak Biswas, Leonid Oliker, adapted are identified by marking environments. Roger Strawn the edges based on an error indica- Point of Contact: R. Biswas tor. The adaption procedure for each (650) 604-4411 Computational methods to solve element is determined from a binary [email protected] large-scale realistic problems can pattern that depends on which of its be made more efficient and cost six edges are marked. The edge data effective by using them in conjunc- structures and pattern marking tion with dynamic mesh adaption ensure that the refinement and procedures that perform coarsening coarsening procedures can be Load Balancing Adaptive and refinement to capture interesting performed efficiently. Unstructured Meshes solution features. Such adaptive The parallel mesh adaption procedures evolve with the solution, procedure has been used to model Rupak Biswas, Leonid Oliker, and they provide scientists a robust the high-speed impulsive noise for a Andrew Sohn and reliable methodology to obtain UH-1H helicopter rotor in hover. A solutions on adapted meshes that are coarse mesh is initially generated Mesh adaption is a powerful tool for efficient, unstructured-grid comparable to those obtained on and additional points are dynami- computations, but it causes load globally fine grids but at a much cally added to capture the acoustic lower computational cost. In addi- wave and the shock near the tip. imbalance among processors on a parallel machine. A novel method tion, with the popularity of distrib- Mesh coarsening is used to remove has been developed to dynamically uted computing, parallel unnecessary points from regions unstructured mesh adaption proce- with smooth solutions; thus, existing balance the processor workloads with a global view. A dual graph dures are absolutely imperative. grid points are redistributed in a representation of the initial computa- An efficient solution-adaptive more efficient manner. A close-up of procedure has been developed for the final grid and pressure contours tional mesh keeps the complexity and connectivity constant during the the simultaneous coarsening and in the plane of the rotor after three course of an adaptive computation. refinement of unstructured tetrahe- adaption steps is shown in the figure dral meshes. An innovative data (see Color Plate 12 in the Appendix). It is a portable system for efficiently performing large-scale adaptive structure, which uses a combination Results show excellent agreement calculations in a parallel message- of dynamically allocated arrays and with experimental microphone data linked lists, allows the mesh connec- for far-field acoustic pressure. passing environment. The first figure depicts the tivity to be rapidly reconstructed Parallel speedup depends on the framework used for parallel adaptive after individual points are added fraction of the mesh that is adapted. and/or deleted. The data structure, When 33% of the mesh was refined, scientific computations. Mesh adaption, repartitioning, processor based on edges of the mesh rather a speedup of 43.2X was obtained on assignment, and data remapping are than the tetrahedral elements, not 64 processors. The speedup im- only enhances the efficiency but proved to 51.5X when 60% of the critical components of the framework that must be accomplished also facilitates anisotropic mesh mesh was refined. rapidly and efficiently so as not to adaption. This scenario means that Current results demonstrate each tetrahedral element is defined significant gains in computational cause a significant overhead to the numerical simulation. The unstruc- by its six edges rather than by its four efficiency when the parallel tured mesh is first partitioned and vertices. Each edge, in turn, main- solution-adaptive method is com- tains a list of all the elements that pared to its fixed-grid counterparts. mapped among the available share it. Thus, elements that need to processors. A solver then runs for several iterations, updating solution

R EVOLUTIONARY TECHNOLOGY LEAPS / Innovative Technology and Tools 59 variables. After an acceptable Initialization Mesh adaptor Load balancer solution is obtained, the mesh adaption procedure is invoked. It Initial mesh Edge marking N Y first targets edges of the mesh for Balanced? coarsening and refinement based on Coarsening an error indicator computed from Partitioning Repartitioning the numerical solution. The old mesh is then coarsened, resulting in

Mapping Reassignment a smaller grid. Since edges have already been marked for refinement, it is possible to exactly predict the Y N Expensive? new mesh before actually performing the refinement step. Program Remapping control is thus passed to the load balancer. If a quick evaluation step Solver Refinement determines that the new adapted mesh will be unacceptably load balanced, a repartitioner divides the mesh into subgrids. The new parti- Fig. 1. Framework for parallel adaptive scientific computation with load tions are then assigned to the balancing. processors in a way that minimizes the cost of data movement. If the remapping cost is less than the computational gain that would be 102 achieved with balanced partitions, all necessary data are appropriately 101 redistributed; otherwise, the new partitioning is discarded. The 100 computational mesh is then actually refined and the numerical calculation is restarted. 10Ð1 An extensive study with a computational mesh used to simu- 10Ð2 late a UH-1H helicopter rotor blade acoustics experiment indicated that Execution time (sec) Ð3 10 Adaption the load-balancing scheme is Partitioning effective for large-scale scientific Ð4 10 Reassignment computations on distributed-memory Remapping machines and scales excellently with 10Ð5 the number of processors. The 0 8 16 24 32 40 48 56 64 second figure shows how the total Number of processors execution time was spent in each module of the framework when the Fig. 2. Anatomy of total execution time. mesh was refined to be more than five times larger than the original.

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The processor reassignment times problem by implementing a library RANS-MP: Portable are almost negligible compared to that provides a grid-independent the other times. The repartitioning approach to CFD data access. Using Parallel Navier–Stokes time is generally independent of the FEL, a single visualization algorithm Solver number of processors. Both the can work on a variety of grid types. R. Van der Wijngaart, adaption and remapping times Very high performance data access Maurice Yarrow gradually decrease as the number is an additional objective in order to of processors is increased. These support interactive visualization, Efficient, cost-effective solution sample results show that none of which allows intuitive exploration of flow problems of interest to the the individual modules will be a of the simulated flow phenomena. aircraft industry requires competi- bottleneck on massively parallel Another objective of FEL is to tively priced hardware and maintain- machines. provide programmers with the ability able, portable software. The current to access, organize, and manipulate generation of parallel computers Point of Contact: R. Biswas field-type data on many types of provides that hardware, and stan- (650) 604-4411 numerical grids at the same time. dard system software such as the [email protected] FEL was fully implemented and message passing interface (MPI) released for structured multizone library provides half of the software and unstructured grid types, proving solution. The other half comes from the grid-independence concept. application programs that employ Initial Release of the Field Data access times averaging algorithms that are tolerant of Encapsulation Library 0.0002 second per access were differences in specific machine measured. These capabilities parameters, most notably the speed Steve Bryson allow the development of high- with which the processors in a performance visualization algorithms parallel computer can exchange Computational fluid dynamics that will work for all supported grid data. The Reynolds-averaged (CFD) simulations are a new way of types. FEL has been integrated into Navier–Stokes with multipartitioning designing and evaluating aircraft the Virtual Windtunnel as well as (RANS-MP) program has been designs on a computer. CFD simula- other individual visualization specifically designed to meet these tions are computed at many points, systems. The concepts behind requirements. forming a three-dimensional grid in FEL were presented at Visualization The newly developed RANS-MP space. The variety of grid types can ‘96, an IEEE peer-reviewed confer- flow solver program employs the greatly complicate the task of using ence held in October 1996 in advanced, bidirectional, multi- computer graphics visualization to San Francisco, California. partition algorithm. This method investigate the CFD simulations (see FEL is an example of a “horizon- limits data movements between the figure (see Color Plate 13 in the tal product,” a set of software processors to a minimum, rendering Appendix)). Visualization algorithms libraries that can be used in a variety it insensitive to the peculiarities can depend very strongly on the type of applications, significantly reduc- of different parallel computers. of grid; an algorithm written for one ing the time required to implement a RANS-MP uses the widely available grid type may not work on another new visualization system. MPI, which means it can run grid type. This problem is particu- efficiently on most of today’s parallel larly acute when developing a Point of Contact: S. Bryson machines. It also employs a pilot general-purpose visualization system (650) 604-4524 for CFD. The objective of the Field [email protected] Encapsulation Library (FEL) project is to solve the grid-dependence

R EVOLUTIONARY TECHNOLOGY LEAPS / Innovative Technology and Tools 61 version of MPI’s companion input/ Although RANS-MP primarily fore, the code must be written to output (I/O) library MPI-I/O, which targets cache-based systems that allow efficient vectorization, the allows efficient scheduling of make up the bulk of the latest high- main source of performance previously prohibitively expensive performance computing architec- improvement on such machines. parallel read and write operations. tures, care has also been taken to When the wing problem is solved on The first figure shows the provide good performance on more the C90, RANS-MP attains a respect- performance of the program on the traditional computers such as the able 45% of the maximum possible Ames Research Center IBM SP-2 Cray C90 and the NEC SX-4. There- performance of the machine. parallel computer in terms of millions of points updated per second by the flow solver. The problem is that of viscous flow 4 around an aircraft wing. A good measure of the quality of a parallel program is its scalability, which is defined as the improvement in Ideal speedup performance as more processors 3 are added to the computation. The figure indicates that, even for a relatively small grid of fixed size of Variable grid size 200,000 points, the scalability is 2 quite good (heavy dashed curve). Performance is even better if the problem size is allowed to grow with Megapoints/sec the number of processors employed Fixed grid size (heavy solid curve). For reference, 1 the ideal speedup curve (thin solid line) is also shown. The second figure indicates the improvement in performance of using the MPI-I/O library over that of 0 the standard, nonparallel I/O library 0 20 40 6080 100 120 on the SP-2, where a gain of up to a Number of processors factor of 30 in write speed can be observed. Fig. 1. Millions of points updated per second on IBM SP-2.

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trillions of floating point operations per second, including: (1) performance tuning, visualization, and analysis; (2) parallel debugging; and 2.00 (3) programming paradigms and MPI-I/O environments. In the first area, an integrated 1.00 performance-tuning environment is developed around the Automated .50 Instrumentation and Monitoring System (AIMS). (See the first figure.) AIMS is a software tool that automatically instruments parallel Megabytes/sec .20 FORTRAN and C programs, monitors their execution on parallel architectures, and displays and .10 analyzes their performance. Dynamic variation of system param- .05 eters and overall performance are Standard I/O automatically captured during execution and subsequently dis-

0 20 40 60 80 100 played on the color screen of a workstation. A key feature of AIMS is Number of processors that it provides source-code click- Fig. 2. Write speed in megabytes per second for MPI-I/O and standard I/O back, allowing the user to relate on IBM SP-2. trace events with specific statements in the application program. AIMS also supports tracking and visualiza- Measurements show that more than Parallel Tools for Parallel tion of interprocessor data move- 99% of all computational statements ments. In addition to providing trace are executed in vector mode. and Distributed Computer Systems information, AIMS has been used to Point of Contact: M. Yarrow investigate the possibility of regener- (650) 604-5708 D. DiNucci, M. Frumkin, R. Hood, ating program trace information from [email protected] H. Jin, L. Lopez, R. Papasin, statistics collected during program C. Schulbach, J. Yan execution. The Numerical Aerodynamic Software tools have been Simulation trace visualizer (NTV) is a developed that accelerate the related tool that provides an alterna- development of Grand Challenge tive to the visualization kernel (VK) Computational Aeroscience applica- of AIMS. Whereas VK provides tions for massively parallel process- dynamic visualization of programs, ing systems. These software tools NTV provides static, zoomable and associated research focus on views. Another product, Ben, is a areas critical to understanding and library of visualization routines that using computer systems capable of can be used to develop visualization capabilities in other software tools

R EVOLUTIONARY TECHNOLOGY LEAPS / Innovative Technology and Tools 63 and products. AIMS is available for the IBM SP-2 (message passing interface (MPI)) and on workstation clusters (parallel vertical machine (PVM) and MPI). NTV supports AIMS traces as well as native traces from the IBM SP-2. The second area involves the development of a debugger for use on parallel and distributed computer systems. The portable parallel/ distributed debugger (p2d2) (see the second figure) is a system using a client/server model that is portable across target machines and communication libraries. This system allows the architecture- and operating system-dependent code to be located in a server while the client- side code remains highly portable. Fig. 1. AIMS software toolkit for automatically instrumenting parallel It was designed with scalable user programs, monitoring their execution, and displaying and analyzing their performance.

Fig. 2. p2d2 being used to debug the running program mp_overflow.

64 R EVOLUTIONARY TECHNOLOGY LEAPS / Innovative Technology and Tools A ERONAUTICS AND SPACE TRANSPORTATION T ECHNOLOGY ENTERPRISE interface elements in expectation Numerical Aerodynamic vendors, and are readily viewable at that users will want to debug the NASA NPB Web site. computations involving many (16 to Simulation Parallel New to NPB2.2 are the IS 256) processes. p2d2 is currently Benchmarks 2.2 integer sort kernel and a vastly available on the IBM SP-2 (for MPI). William Saphir, improved FT Fast Fourier Transform Development of support for PVM R. Van der Wijngaart, kernel. Unlike the other kernels that has also been completed. Alex Woo, Maurice Yarrow measure floating-point performance, In the third area, programming the IS code does integer operations paradigms and environments, the The Numerical Aerodynamic only and measures raw processor Cooperative Data Sharing System Simulation (NAS) Parallel Bench- power. It also provides a strenuous (CDS) has been developed to marks 2.2 (NPB2.2) bring a new era test of the speed of the communica- provide an efficient, portable, and of integrity to the performance tion network of a modern parallel simple system for creating processes claims of the vendors of high- computer. The new FT program, no and communicating between them performance parallel computers. longer limited to 128 processors, has in cluster, message-passing, and NASA is an immediate beneficiary had its floating-point performance shared-memory environments. This of these benchmark tools, as is the improved. The three application setup allows the user to specify the scientific and engineering commu- benchmarks known as BT, LU, and semantics required of each community at large, since evaluation of SP solve equations of viscous flow, nication so that it can execute with high-performance computers can each with a different algorithm. near-optimal performance on any now be based on objective perfor- The remaining two kernels solve a target architecture: shared-memory, mance criteria rather than vendor multigrid problem and a so-called message-passing, or cluster. The hyperbole. The NPB2.2 also stand “embarrassingly parallel” problem. CDS application user interface out as excellent source code models The suite provides a comprehensive consists of two layers: a kernel for the development of future test of the capabilities and relative level (CDS1), with objectives of parallel versions of simulation performance level of a parallel minimality, orthogonality, portabil- programs for the aerospace industry. computer, making the task of ity, efficiency, and utility; and a user NPB2.2 consist of source code assessing high-performance comput- level (CDS2) built upon CDS1, with versions of seven computational ers for NASA laboratories easier than the sole objective of providing a fluid dynamics applications and ever before. useful user interface without interfer- kernels that were originally given as Point of Contact: M. Yarrow ing with the desirable characteristics “paper and pencil” specifications. In (650) 604-5708 of CDS1. CDS1 is available on SUN their original form, they gained wide [email protected]’ Solaris and Silicon Graphics Inc. acceptance as measures of parallel Challenge Array systems. computer performance, but vendor implementations were machine- Point of Contact: C. Schulbach specific and proprietary. The current (650) 604-3180 source code versions, however, have [email protected] Large-Scale Parallel been specifically designed to run on modern parallel computers that Semiconductor Simulation support the commonly available Subhash Saini message passing interface (MPI). They are available from the World At the present time, several Wide Web, and have been designed technologies are pressing the to be extremely easy to use. Data limits of the semiconductor-based generated by these benchmarks are computer industry, including the now available for a wide variety of 0.1-micron foreseeable limit of the parallel computers from numerous photolithography process, quantum

R EVOLUTIONARY TECHNOLOGY LEAPS / Innovative Technology and Tools 65 strategy for implementing parallel 1016 adaptive unstructured-grid technol- 15 Enhanced evolution ogy for semiconductor device 10 1 Pflop/s modeling has been developed. This 14 10 strategy addresses the important

1013 Normal evolution issues, such as load balancing. Also studied were the scaling properties Highly parallel 1 Tflop/s 1012 Conventional supercomputers DM computers of several algorithms, such as fast 1011 multipole expansions (FME) to determine the trade-off between FME 10 RISC SMPs 10 and long-range molecular dynamics 1 Gflop/s 109 methods in terms of computational cost. Both these methods are used in 8 RISC workstations 10 device modeling.

Floating point operations per second (Flop/s) 107 1990 1995 2000 2005 2010 Point of Contact: S. Saini Year peak performance first reached (650) 604-4343 [email protected] Fig. 1. High-performance computing technology roadmap.

EVOLUTIONARY ECHNOLOGY EAPS R REVOLUTIONARY TTECHNOLOGY LLEAPS// ␣␣SUPERSONIC TECHNOLOGY SUPERSONIC TECHNOLOGY effects, heat dissipation, the skyrock- atmosphere and climate; and the eting cost of manufacturing plants, design, manufacture, and operation and others. NASA requirements for of smart nanorobots for space high-performance computers are exploration. different from those of mainstream A roadmap for the high- Nonlinear Aerodynamic industry. For many applications, performance computing industry has Shape Optimization of such as the High-Performance been developed and is presented in High-Speed Research Computing and Communication the figure. Current consensus is that (HPCC) remote exploration and petaflops computing systems will be Configurations experimentation (REE) project, NASA feasible in 20 years using advanced Susan Cliff, James Reuther, Ray Hicks requires low-powered, ultracompact, semiconductor technology. Ames high-performance computers that are Research Center has instituted a new The overall goal of this research resistant to radiation damage. By the program in semiconductor process is to develop an aerodynamic shape year 2010, many important future and device modeling to ensure that optimization technique that is based NASA missions will rely on petaflops NASA will be able to meet future on nonlinear computational fluid computer systems. Applications of requirements of petaflop computing. dynamics (CFD) methods and interest to NASA that will most likely In spite of the seemingly obvious control theory techniques; eliminates require petaflops computing include need for highly parallel computing the dependence on a large number multidisciplinary optimization of as a simulation and design tool in of CFD solutions; and can be commercial aircraft designs, propul- this arena, so far any utilization of effectively used to optimize aero- sion systems, large-eddy and the parallel systems has been rare. The dynamic shapes to yield superior direct numerical simulation of principal impediments include aerodynamic performance. In turbulence; computation of the radar access to parallel testbeds, as well as support of the high-speed research scatter signature of aircraft bodies; the availability of usable software (HSR) program, the specific objec- full-scale simulation of the Earth’s and parallel computing expertise. A tive is to apply these methods to

66 R EVOLUTIONARY TECHNOLOGY LEAPS / Innovative Technology and Tools A ERONAUTICS AND SPACE TRANSPORTATION T ECHNOLOGY ENTERPRISE

candidate configurations to assess differences to obtain the necessary constraints, including wing spar their capabilities and simultaneously gradient of an aerodynamic objec- depth, wing leading edge bluntness, enhance the aerodynamic perfor- tive function (for example, drag) with landing gear box size and location, mance of the vehicle. respect to the design variables. Thus, fuel volume, passenger cabin The aerodynamic design for if N is the number of design vari- dimensions, and floor attitude. The supersonic cruise of high-speed ables used for the shape design, then optimization procedure used up to commercial transport aircraft is an N flow solutions are required to 140 independent design variables extremely difficult problem because obtain the gradient during each distributed over the wing and of the complex flow fields and the design cycle. Through the use of fuselage and focused on wing need to efficiently integrate the control theory-based methods, a set thickness and camber and fuselage major components of the vehicle of adjoint equations are formulated camber and area distribution. Over (i.e., the fuselage, wing, and engine that reduce the computational 200 design iterations were executed nacelles) while satisfying numerous requirement down to the equivalent in the overall design process, and structural and operational con- of two flow solutions, independent they yielded very significant perfor- straints. Past design efforts have of the number of control variables. mance gains relative to the baseline. relied upon linear theory methods. The result is a computational savings These performance gains were Unfortunately, the near-field of greater than an order of magni- validated through numerous detailed interactions of the components are tude. Furthermore, since the gradient Euler and Navier–Stokes analyses. nonlinear and the use of linear calculations are no longer depen- Hardware is currently being fabri- theory-based design methods dent on the number of design cated for a wind-tunnel test to provides only limited design guid- variables, the shape of complex experimentally validate the results. ance. Furthermore, the level of configurations can be optimized This design/optimization cruise aerodynamic performance using a large number of design approach represents some of the first achievable with linear design variables. successful attempts to use the power methods is insufficient to ensure an Using the nonlinear design/ of CFD as a true design tool applied economically viable configuration. optimization code named SYN87 to complex aircraft configurations The role of CFD in the aero- and its predecessors OPT3D and with a large realistic spectrum of space industry today is primarily OPT67, which combine Euler flow constraints. In addition, the large that of an analysis tool used in the solvers with constrained and uncon- performance gains achieved clearly final stages of the design process. strained numerical optimization demonstrate the advantage of Although this tool has proved very algorithms, five successful aero- using nonlinear design methods to beneficial, to make full use of the dynamic designs have been accom- enhance aerodynamic performance. power of CFD it must be incorpo- plished. The first four designs have Point of Contact: D. Bencze rated into the framework of an been validated through wind tunnel (650) 604-6618 automated design process. Past testing. The most recent application [email protected] efforts to accomplish this objective of this automated aerodynamic have proved extremely difficult for design process, which used SYN87 applications involving complex and the adjoint gradient computa- aircraft configurations because of the tions, was focused on the Mach 2.4 computational expense associated HSR Technology Concept Airplane with the thousands of CFD solutions (TCA). The cruise aerodynamic that are required to gain an under- shape of this configuration (shown in standing of aerodynamic design the figure (see Color Plate 14 in the space and its related optima. Appendix)) was optimized to obtain Traditional aerodynamic shape the minimum drag subject to a large optimization methods use finite spectrum of realistic geometry

R EVOLUTIONARY TECHNOLOGY LEAPS / Supersonic Technology 67 Surface Operations Behavioral Evaluation Interim Testbed for High-Speed Research Mary K. Kaiser

The eXternal Vision System (XVS) element of the high-speed research (HSR) program is examining issues associated with building a high-speed civil transport (HSCT) with no forward-looking windows. Forward visibility would be provided by a synthetic vision system, generally conceived as displaying visible light camera imagery with superimposed symbology. This design Fig. 1. The SOREV. Externally mounted cameras feed the forward and concept presents numerous engi- inboard displays at the rear driver station. An outboard side window is neering and human factors chal- configured to simulate the side window visibility planned for the HSCT. lenges, including the adequacy of the XVS display for control, navigation, and obstacle detection; Ames has worked with industry “first looks” at critical human factors integration of the XVS display with partners at Boeing and Honeywell to issues associated with the XVS and the side windows (which are opti- equip a full-size Ford van (shown in surface operations. the figure) with an XVS system cal); and crew coordination in an Point of Contact: M. Kaiser located at a rear driver station. The XVS-equipped flight deck. (650) 604-4448 rear station has two XVS displays Surface operations may present [email protected] particular challenges to an XVS- (forward and inboard) and an optical equipped aircraft because vehicle window with the visibility angles control is primarily vision-based specified by the Reference H design (compared to many phases of flight of the HSCT. The cameras can be in which the pilot relies heavily on mounted at several locations on the instrument information) and because vehicle, creating parallax similar to artifacts such as sensor-offset that anticipated with aircraft parallax become more severe when mounted camera systems. Transport the aircraft is close to the ground. delays in the camera/display system To examine these surface can be introduced, and the impact operations issues in a high-fidelity on driver control and situational testbed, the HSR program is con- awareness can be examined. structing a near-full-scale testbed, Although its overall fidelity is the Surface Operations Research somewhat limited, the SOREV is Evaluation Vehicle (SOREV). The proving to be a useful testbed for SOREV is scheduled to be operational in late FY97. In the interim,

68 R EVOLUTIONARY TECHNOLOGY LEAPS / Supersonic Technology A ERONAUTICS AND SPACE TRANSPORTATION T ECHNOLOGY ENTERPRISE

R REVOLUTIONARYEVOLUTIONARY T TECHNOLOGYECHNOLOGY LLEAPSEAPS// Health Management to an opera- ␣␣AACCESSCCESS TO TO S SPACEPACE tional cryogenic testbed; and (4)␣ testability models developed by using a software tool set from Propulsion Checkout and QualTech Systems, Inc. were used in Control System positioning the IPTD sensors. Ann Patterson-Hine The design models were automatically converted to real-time The Propulsion Checkout and code that monitored sensor data and Control System (PCCS) was part of that worked with the Langley smart- the Integrated Propulsion Technol- sensor routines to identify off- ogy Demonstrator (IPTD) task nominal conditions to the operator. supported by the X-33 program. This successfully demonstrated The objective of the IPTD was to Rockwell’s approach to reducing predict and evaluate potential software development costs by improvements in ground and flight reusing design models and software propulsion-system operations in for operational vehicle code. efforts to reduce turnaround times Point of Contact: A. Patterson-Hine and to cut cost-risk factors. The IPTD (650) 604-4178 consists of liquid-oxygen and liquid- [email protected] hydrogen propulsion modules, a remote interface unit that is a prototype of Rockwell’s X-33 Phase␣ II propulsion system avionics- to-control-center interface, and a prototype control center at Marshall Space Flight Center’s (MSFC’s) Advanced Engine Test Facility. The task, which was completed in FY96, achieved the following: (1)␣ on-board diagnostic/prognostic algorithms for the propulsion system of the Reusable Launch Vehicle were demonstrated to be capable of trending and analyzing a historical database; (2) playback of IPTD data on valve actuations identified early performance degradation of the 12-inch prevalve in the main propulsion system that otherwise would have been undetectable; (3)␣ the diagnostic/prognostic algorithms are the first known application of predictive Integrated Vehicle

R EVOLUTIONARY TECHNOLOGY LEAPS / Access to Space 69 Space Science Enterprise

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O v e r v i e w life) since the inception of these NASA’s Space Science Enter- disciplines. Research at Ames prise seeks answers to fundamental focuses on revealing how life begins, questions about the origin of the on what processes govern its evolu- Universe, the origin and evolution of tion, on what destiny may be galaxies and planetary systems, the realized, and on how often life may origin and distribution of life in the have emerged on other planets. Universe, and the connections When coupled with Ames’ pioneer- between the Sun, Earth, and helio- ing research on the dynamics of sphere. Through our primary mission galaxies, molecular gases and in astrobiology (the study of the clouds, planetary systems, and the living Universe), Ames provides Solar System, our study of life is pioneering research, technology facilitated by understanding the development, and flight projects that cosmic environment within which promote fundamental discoveries life evolves. Ames conducts studies about the origin, evolution, and of biologically important materials in distribution of life within the context geologic samples and in extrasolar of cosmic processes. Research is matter; provides theoretical insights conducted to: for addressing major issues in life’s evolution; plays a key role as ␣ ␣ •␣ ␣ Determine the abundance and NASA’s expert in matters of plan- distribution of biogenic cometary protection; and helps to focus pounds that are conducive to the science for future Mars missions the origin of life on issues related to the possibility of ␣ ␣ •␣ ␣ Identify locations in the Solar the independent origin of life on System where conditions Mars. conducive to life have existed One of the most important ␣ ␣ •␣ ␣ Survey and begin surface questions in exobiology and astrobi- explorations of the most fasci- ology is how living systems emerge nating and accessible planetary from molecular chaos. Highlighted bodies in this report are exobiological ␣ ␣ •␣ ␣ Discover the origin, evolution, simulations that revealed several and fate of the Universe, galax- new and important basic principles ies, stars, and planets governing the ability of peptides to ␣ ␣ •␣ ␣ Survey cosmic rays and interstel- acquire ordered structures, to self- lar gas as samples of extrasolar catalyze, and to give rise to a simple matter mechanism for transmitting signals ␣ ␣ •␣ ␣ Explore the frontiers of the from the external environment to the heliosphere interior of a protocell. ␣ ␣ •␣ ␣ Search for planets and planetary The role of comets in the origin formation around other stars of life is also featured. Comets, which can be considered the fossils of the protoplanetary nebular Exobiology and Astrobiology processes, retain within their icy Ames has been recognized as a nuclei clues about the beginning of world leader in astrobiology and the Solar System. Ames reported an exobiology (search for extraterrestrial important finding this year on the

71 composition and properties of oxidants—a primary obstacle to Galaxy, hinting at common evolu- interstellar and cometary ices that uncovering the biological history of tionary processes. A complementary may have profound implications for Mars; and a unique concept, the Ames study on PAHs revealed that a our understanding of the origin Pascal Mission, to use Mars as a new type of PAHs, hydrogen PAHs of life. natural laboratory for the study of (H-PAHs), found at the boundary of factors that control a planet’s climate the Orion Nebula and Orion Planetology system. Molecular Cloud, are absent in Ames conceived and initiated higher-radiation environments. 7␣ of the 11 planetary missions that Astrophysics Results presented in this report have flown since 1972, including As NASA’s lead Center in indicate that different chemically the Mars Pathfinder. The Galileo airborne astronomy, Ames pioneered active regions in planetary nebulae probe made history on December 7, and developed astrophysics and has and molecular clouds are defined— 1995, with its entry into the atmo- the world’s only capability for at least in part—by the characteris- sphere of Jupiter, the first time a making astronomical observations tics of the radiation environment. spacecraft entered the atmosphere from the stratosphere. Development Protoplanetary nebulae, the of an outer planet. Plunging into was begun this year on the Strato- birthplaces of planets and planetary Jupiter’s swirling storm clouds at spheric Observatory for Infrared systems, are distributed throughout 106,000 miles per hour, the probe Astronomy (SOFIA), the infrared the Universe. The “primary accre- descended 400 miles through telescope of which will gather tion” process—the process by which turbulence, violent winds, and almost an order of magnitude more the first sizeable objects (comets, clouds, transmitting data for almost light than its predecessor and asteroids, etc.) formed from solids an hour before the communications achieve a five-order-of-magnitude that entered a given protoplanetary system succumbed to the intense improvement in capability. Ames nebula as micron-sized dust motes— Jovian environment. Results from the astronomers, who also contribute is one of the major unsolved prob- probe’s descent are reported below. directly to space-based infrared lems of the origin of planetary Ames also recently completed a science, won the right to the most systems. A new insight, achieved comprehensive study of the Solar observation time on the premier this year upon completion of a new System which fully models the entire infrared space mission of the model of turbulence and damping range of bombardment, transport, decade—the European Infrared by particles in the midplane of a and mixing effects by which highly Space Observatory. These and the protoplanetary nebula, challenges absorbing “primitive” interplanetary highlights described below are certain theories of accretion material pollutes, and redistributes presented more fully in later sections dynamics. material in, an initially pristine icy of this report. Ames researchers recently system such as Saturn’s rings. Ames and the University of completed the most comprehensive Surprising findings are described in Tokyo produced the Mid-Infrared theoretical computation of the this report. Spectrometer on the Japanese potential energy surface and dipole Of all the planets in the Solar Infrared Telescope mission which moment for hot water in sunspots System, Mars is most like Earth, obtained infrared spectra of more of the Sun and in the spectra of especially in that its weather and than 10,000 objects and has yielded selected cool stars, revealing that climate are dynamically similar to interesting new information on the sunspot atmospheres are much Earth’s and in that its history may character of the interstellar material. cooler in the shallow layers than had have included life. Research high- Results obtained this year confirm been predicted by previous models. lighted in this report includes a that two types of interstellar mate- These results and other potential new finding on the structure of the rial—grains and certain polycyclic applications of the model are Martian regolith and its role in the aromatic hydrocarbons (PAHs)—are highlighted in this report. Martian climate; the results of Ames mixed in a constant ratio throughout The final stages in the life of a research on the nature of the Martian different interstellar regions of the star somewhat more massive than

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the Sun was studied by Ames the face of a wide variety of faults, dynamic range. WaveLab is avail- researchers and colleagues from including total loss of command and able at no cost to the public on a the University of Hawaii and the control from Earth. World Wide Web site maintained at University of Wyoming. The results Live tests of a key component of Stanford University. provide an important insight into the Automatic Telescope Project Significant progress has been understanding how the structural were successfully completed. The made in understanding and improv- evolution of the nebula, through primary objective is to provide ing the operation of two of the main interacting winds, might provide the advanced scheduling and automa- components of a pulse-tube conditions necessary for molecular tion infrastructure so that the cryocooler for use in spacecraft. In survival. benefits and performance of single- addition, Ames developed a star Also described in this issue is a user automatic telescopes can be sensor that can be mounted in a remarkable “hands-on” educational made available to a large commu- cryogenic vacuum vessel to serve as software package developed by nity of users, with no additional a guide star-tracker for the Gravity Ames that allows students of all ages people in the loop. The benefits will Probe B relativity mission. to perform simulated observations of be a dramatic reduction in telescope planets around other stars, as if they operating costs and an increase in were the astronomers, and then to both scientific productivity and ease analyze the data to determine the of use. habitable properties of the planets. Ames’ Assisted Space System Included in the package is a descrip- Experimental Testbed (ASSET) tion of Ames’ proposed Kepler project is an Internet-based global mission, the only currently practical spacecraft control network that method for finding Earth-sized provides operational support of a planets around other stars. variety of low-cost missions and a high-risk, low-inertia testbed for Space Technologies validating spacecraft autonomy To support the Space Science strategies. This year ASSET enabled Enterprise, Ames scientists and rapid experimentation with revolu- engineers develop, validate, and tionary autonomy technologies in a verify enabling, cutting-edge, high- real-world, complex space system payoff technologies for conducting in support of the New Millennium future space science and exploration program concerning the data missions at substantially reduced distribution, principal investigator costs. Cost reduction is achieved interfacing, beacon operations, principally by using information ground-system automation, and fault technology to develop advanced management. flight- and ground-system autonomy Ames has developed WaveLab, technologies. The following high- a powerful suite of wavelet algo- lights are reported more fully in later rithms that can be used to character- sections. ize the physical processes An executive system for intelli- underlying complicated temporal gent autonomous spacecraft, and spatial variations, removing planned for the Deep Space One unwanted observational noise from mission, was prototyped this year. data, compressing data with insig- Deep Space One will autonomously nificant loss of information, and navigate to asteroids and comets and probing computer models for will be able to achieve its mission in physical processes with large

73 PROGRESS PROGRESS IN INEXOBIOLOGY EXOBIOLOGY XRD data from the prototype The Rietveld method, which fits CHEMIN instrument. the entire observed diffraction X-ray diffraction is the most pattern with a pattern calculated Remote Analysis of direct and accurate analytical using the crystal structures of the Martian Surface Materials method for determining the presence constituent phases of the model of mineral species, because the data mineral system, shows great promise D. Blake, P. Sarrazin, D. Bish, obtained by this method are funda- for mineral analysis. This method D. Vaniman, S. Chipera, S. A. Collins, mentally linked to crystal structure. can provide rapid quantitative T. Elliott Other methods, based on chemical estimates of mineral abundance, as or spectral properties, are derivative well as compositional, unit-cell A miniaturized x-ray diffraction and subject to much greater uncer- parameter and structural data on and x-ray fluorescence (XRD/XRF) tainties. Moreover, significant individual minerals. In addition, instrument for exploring the Mars progress has been made in the last recent advances in quadratic goal surface is being developed; the decade in the development of programming allow solution of instrument will minimize the quantitative XRD of multicom simultaneous linear equations using uncertainties inherent in remote ponent mixtures. mineralogical and geochemical analyses. The instrument has been named CHEMIN, in reference to its role as a simultaneous chemical and mineralogical analyzer. A functioning prototype of this instrument uses a copper X-ray tube, transmission geometry, and an energy-selective charge-coupled device (CCD) operating in single-photon counting mode to collect simultaneous XRF and XRD data. The ultimate use of this instrument will be in obtaining combined XRD and XRF data from planetary samples. Such an approach will greatly improve the accuracy of remote petrological analyses by constraining the number of possible mineralogic interpretations of the data. For example, although the Viking landers provided very useful XRF data on the Martian regolith, the complex chemistry reported (particularly the mixed-anion suite that includes sulfur and chlorine, as well as oxygen) allows a wide range of mineralogic interpretations. Since Fig. 1. Two-dimensional image of basalt diffraction pattern obtained with remote XRF has yielded proven the CHEMIN instrument using only monoenergetic copper-characteristic results, the focus is on preliminary radiation. The rings correspond to lattice spacings within individual minerals tests in obtaining quantitative making up the basalt.

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chemical and mineralogic data. Use of these techniques with combined 3200 bulk-sample XRD and XRF data Observed pattern Calculated pattern makes possible extraction of consid- 2800 erable information on individual mineral compositions. 2400 To test the capabilities of CHEMIN against realistically com- 2000 plex samples, Rietveld analysis was used to determine mineral abun- 1600 dances from CHEMIN-derived Intensity diffraction patterns of a basalt. This 1200 sample was chosen as representative Background of a rock type that is known to be 800 abundant on the Martian surface, and also one that fits the generic 400 mineralogy of all of the Mars Difference pattern 0 meteorites identified so far (includ- 8 12 16 20 24 28 32 36 40 44 48 ing the ALH84001 meteorite pur- 2θ (°Cu) ported to contain evidence of primitive Martian bacteria). Fig. 2. Rietveld refinement of the diffractogram obtained by summing x-ray XRD and XRF data were intensities shown in Fig. 1 radially around the central beam. The patterns are obtained from a sample of terrestrial evaluated by least-squares fitting between model and actual results. basalt with the prototype CHEMIN instrument using repetitive 30-second counts. After accumula- plotting the two-dimensional agrees well with the observed tion of numerous 30-second-count distribution of those pixels contain- pattern. In addition, the resulting datasets, the data were analyzed on ing copper-characteristic radiation mineral analysis agrees well with a pixel-by-pixel basis. X-ray powder (first figure). The powder rings were optically determined modes for this diffraction rings were generated by then integrated to generate conven- sample. This level of success has tional 2θ-versus-intensity powder- only recently been obtained, and diffraction patterns (2θ is the angle considerable improvement in the Table 1. Rietveld quantitative between the diffracted beam and the CHEMIN results are anticipated in analysis of basalt sample entering beam). The resulting XRD the near future. data were used as input to Rietveld The CHEMIN instrument has Mineral Weight, % refinements. The results of the been proposed for a number of Forsterite 7.5 analysis are shown in the table and space missions, and an XRD/XRF Albite 28.9 in the second figure. Despite the capability is included in instrument complexity of the basalt sample and suites proposed for Mars landers and Anorthite 17.5 the significant limitations of the rovers by several working groups. Augite 4.7 prototype CHEMIN instrument, the Point of Contact: D. Blake Magnetite 1.9 Rietveld analysis is surprisingly (650) 604-4816 Phlogopite 0.1 good, with a calculated pattern that [email protected] Florapatite 1.6 Sanidine 37.9

P ROGRESS IN EXOBIOLOGY 75 Stable Isotope The stable isotopic composition deposits tend to increase with of the elements oxygen (O), hydro- declining temperature and thus Biogeochemistry of gen (H), sulfur (S), and carbon (C) in help to map temperature gradients Hydrothermal Systems minerals and other chemical species within hydrothermal systems. The 13 12 David J. Des Marais can indicate the existence, extent, C/ C values of carbonates and conditions, and processes (including 13C-depleted microbial organic Hydrothermal systems probably biological activity) of hydrothermal carbon increase along the thermal existed in any rocky planet which systems. The reactions between hot gradients of thermal spring outflows, was sufficiently large to accumulate water and rock-forming minerals principally because of the outgassing substantial internal heat from allow the isotopic ratios 18O/16O of of relatively 13C-depleted carbon radioactive decay and which also deuterium to hydrogen (D/H) of the dioxide (CO2). Hydrothermal waters possessed a significant crustal minerals to equilibrate with this can differ in their D/H contents inventory of water. Hydrothermal water, causing isotopic changes because of their variety of sources, systems provide the liquid water, which can be used to detect fossil which can include seawater or nutrients, reduced conditions, and systems and to delineate their areal rainwater, which falls over ranges in chemical energy necessary to extent. These isotopic changes can elevation and geographic location. support life. Therefore NASA’s indicate fluid composition, alteration Therefore, measurements of D/H astrobiology and solar system temperatures, water-rock ratios, and values in hydrothermal minerals can exploration programs should include so forth. The 18O/16O values of help to decipher the origins of the a search for hydrothermal systems in hydrothermal silica and carbonate fluids. The 34S/32S and 13C/12C other planets. values of fluids and minerals reflect the origin of the S and C, the partial pressure of O2, and also the nature Biosynthesis CO2: of key oxidation-reduction pro- Sea, Atm. cesses. For example, a wide range 34 32 Decomposition of S/ S values is consistent with ° Marine equilibration below 100 C between Fresh organic matter Ð HCO3 sulfide- and sulfate-bearing minerals, Decomposition and burial Burial and can be attributed to sulfur Weathering Carbon- metabolizing bacteria and not to Sedimentary organic matter Out- ates nonbiological processes. Depending gassing on its magnitude, the difference in Hydrothermal Hydrothermal the 13C/12C value between carbon- CO and carbonate reduced carbon 2 ate minerals and coexisting organic carbon can be attributed either to Subduction Mantle equilibrium at hydrothermal tem- carbon Subduction peratures or, if the difference in the ratio exceeds 1%, to organic biosyn- Ð40 Ð30 Ð20 Ð10 0 +10 thesis (see figure). δ13 C The observations of hydrothermal mineral assemblages and Fig. 1. Carbon isotopic composition of crustal carbon reservoirs, with coexisting organic carbon in special emphasis on hydrothermal systems. The horizontal axis depicts Yellowstone National Park indicate variations in 13C/12C values in parts per thousand, with lower values to the that both temperature gradients and left. Boxes and arrows depict carbon reservoirs and processes linking the microbial communities can indeed reservoirs, respectively. The isotopic composition of hydrothermal carbon be documented through measure- species can be affected both by mantle carbon and by contamination from ments of their oxygen and carbon crustal sources of organic and carbonate carbon.

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isotopic compositions. Parallel early history of Earth, it is likely that to create a framework for recogniz- measurements are now being hydrothermal systems were wide- ing such deposits in the Precambrian made in rocks from an ancient spread owing to higher internal heat record, the authors have been (400-million-year-old) hydrothermal flow, and to the thermal energy carrying out studies of modern system in Queensland, Australia. invested by large impacts. Thus, thermal-spring systems in hydrothermal environments are Yellowstone National Park, along Point of Contact: D. Des Marais regarded as key environments for the with ancient deposits from localities (650) 604-3220 origin and early evolution of terres- in western North America and [email protected] trial life, a view that also receives Australia. support from the universal tree of life In FY96 studies of modern derived by comparing the nucleic thermal springs led to several acid base sequences in the RNA of discoveries that have helped refine Fossilization Processes in living organisms. The patterns of the understanding of stromatolite Thermal Springs early branching suggest that the morphogenesis and fossilization common ancestor of all living processes at high temperatures. Jack Farmer, Sherry Cady, organisms was an extreme thermo- Columnar geyserites (see first figure), David J. Des Marais phile, that is, a microorganism that are high-temperature subaerial preferred living at temperatures splash deposits that form around the Stromatolites are laminated above 80°C (176°F). vents of siliceous thermal springs. biosedimentary structures that form The fossil record of thermal- The structures thus formed resemble when communities of microorgan- spring deposits is virtually unknown, many Precambrian stromatolites. isms either entrap sedimentary and no subaerial systems have yet Columnar geyserites were first grains, or induce the precipitation of been recognized in the ancient studied in the late 1970s and minerals through their metabolic geological record of Earth. In order determined to be abiogenic (that is, processes. Fossil stromatolites provide a primary source of information about the early biosphere on Earth, and have also been identified as important targets in the exploration for a fossil record on Mars. These megascopic biosedimentary structures are rich storehouses of paleobiological information and often contain not only the fossilized remains of the microorganisms which produced them, but also biochemical and isotopic signatures that directly link them to life processes. Thermal springs are highly productive microbial factories that provide an important glimpse into the nature of the primitive biosphere. In recent years, the microbial communities and stromatolites of thermal springs have assumed a Fig. 1. Thin-section view of columnar stromatolites (geyserites) formed prominent place in studies of around high-temperature vents of silica-depositing springs in Yellowstone primitive biospheres. During the National Park; columns are about 3 mm high.

P ROGRESS IN EXOBIOLOGY 77 Molecular Biomarkers for Stromatolite-Building Cyanobacteria Linda L. Jahnke, Roger E. Summons, Harold P. Klein

Life began on early Earth in an environment devoid of free molecular oxygen (O2). It is clear that the rise of O2 as a consequence of the evolution of oxygenic photosynthesis had a profound effect not only on the subsequent progression of biological evolution but also on Earth’s geological history. Although oxygenic photosynthesis evolved within the cyanobacterial lineage, Fig. 2. Thin-section view of fossilized microbes from 350-million-year-old evidence for this event’s timing siliceous thermal-spring deposits discovered in the Drummond Basin of remains obscured within the northeast Queensland, Australia; individual filaments are about 20 µm in molecular and rock records. One diameter. potential help in resolving this issue resides in the complex organic not produced by living organisms). Observations were made of the molecules that can be extracted from Since that time, some authors have primary biofabrics and microfossils ancient sedimentary rocks. These questioned the biogenicity of the that are preserved in these ancient molecules, called biomarkers, are oldest fossil stromatolites, suggesting deposits, despite extensive textural the remnants or molecular fossils of that they were also formed inorgani- reorganization during diagenesis ancient microorganisms. The carbon cally. But studies of modern geyser- (second figure). skeletons of such fossil molecules ites have shown conclusively that can survive structurally intact for Point of Contact: J. Farmer these deposits are actually formed in billions of years, and organic (650) 604-5748 the presence of thin biofilms of geochemists are working to identify [email protected] thermophylic bacteria and archae- them in ancient organic sedimentary bacteria, and that the geyserite materials. The challenge is to microstructure reflects a significant understand the link between such biogenic contribution. molecular fossils and their “living” In FY96 the first detailed paleon- counterparts, the biomarker mol- tological studies of ancient subaerial ecules synthesized by contemporary thermal-spring deposits in northeast bacterial groups. Understanding the Queensland, Australia, were also function and influence of environ- completed. These 350-million-year- mental factors on the synthesis of old deposits are precise analogs for such biomarker molecules in the the modern subaerial systems that source organism can then provide a have been studied in Yellowstone. basis for interpretation of this ancient organic record.

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of cyanobacteria to determine the extent to which this low DIC-DMA synthesis phenomenon occurs. To date, we have screened 6␣ marine and 12 freshwater strains of cyanobacteria. None of the marine cyanobacteria, including several Synechococcus, three Oscillatoria, and a Pseudanabaena were able to synthesize DMA. This was also true for a variety of cyanobacteria (Gloeocapsa, Synechococcus, Oscillatoria, Pseudanabaena) isolated from the hot spring, microbial mats in Yellowstone National Park. Two other Yellowstone isolates, Chlorogloeopsis and Fischerella, did synthesize dimethylalkanes, but these com- µ Fig. 1. Photomicrograph of a Phormidium (filament width 1.5 m) isolated pounds differed in carbon chain from a Yellowstone microbial mat. length and methyl group positions, and were synthesized under both high and low DIC conditions. The Extant cyanobacteria are a cyanobacteria, are resistant to biodegradation, and form some of only cyanobacteria found to be diverse group of prokaryotic micro- capable of dimetylheptadecane organisms found in a wide variety of the oldest known biomarkers, having been isolated from Proterozoic rocks synthesis were four Phormidium modern environments. We have types isolated from siliceous hot focused our study on the types of dated at 1.7 billion years ago. More recently, we have identified another springs (see first figure). Like cyanobacteria involved in the Phormidium luridum, the construction of microbial mats and class of methylated alkane having two methyl branches at carbons 7,11 Yellowstone Phormidium contained their fossilized equivalents, stroma- high levels of DMA when grown tolites. These laminated, organo- or 7,10 in a cyanobacterium, Phormidium luridum. We found that under low DIC conditions. sedimentary structures are among The Phormidium are responsible the most common fossils in the these dimethylheptadecanes (DMA) were only synthesized when the for the formation of a type of colum- geological record. Important nar stromatolite, the Conophytons biomarkers for identification of cyanobacterium was grown with low levels of dissolved inorganic carbon (conical-formed microfossils). cyanobacterial input to sedimentary Conophytons were one of the most organic matter are a group of (DIC). Cells grown with DIC levels equivalent to atmospheric levels of distinctive groups of stromatolites straight-chain hydrocarbons which disappeared near the end of (alkanes) having 17 to 20 carbons carbon dioxide (CO2) (0.03%) contain DMA, whereas cells grown the Precambrian. The Phormidium (C17-C20) with midchain, mats in Yellowstone provide a branched methyl groups such as with 1% CO2 have only a straight- chain n-heptadecane. We have surviving “primitive” analog for 7-methylheptadecane (C17). These methylalkanes are specific to carried out a screening of a variety

P ROGRESS IN EXOBIOLOGY 79 Earth-Threatening Comets Leave Tell-Tale Dust Trails Peter Jenniskens, David Morrison

Over its geologic history, Earth has been bombarded by a continuous shower of large asteroids and comets, some of which led to large- scale extinctions. Unlike other dangers, impacts of larger bodies can affect mankind as a whole and pose a threat to modern civilization. The first step toward avoiding such impacts is to know where the potential impacting objects are. Most large asteroids can be found by dedicated searches using large telescopes, because they have a short orbital period and come close to Earth frequently enough to be detected. However, that is not the case for comets with long orbital periods, which come back to the inner parts of the solar system only once every 200–100,000 years. And some 2 to 10% of all such impacts are thought to be due to these long- Fig. 2. Silicifying Phormidium mat (width 12 inches) showing Conophyton period comets. structure, Weeds Pool, Yellowstone National Park. Researchers are studying the possibility of using the meteoroid particles in the path of these comets study of the Conophytons (second Yellowstone Phormidium mats may as a means of detecting their pres- figure). DMA are found only in provide important insights for ence. From numerous accounts of Precambrian oils, and disappear interpretation of the organic molecu- amateur observers, they know that from younger organic sediments just lar fossil record. some meteor streams show brief as the Conophyton stromatolites Point of Contact: L. Jahnke episodes of high activity: the meteor disappear from the rock record. The (650) 604-3221 outbursts. At such times, Earth environmental factors controlling [email protected] crosses relatively recent ejecta of dimethylalkane synthesis in the particles, which evaporate in Earth’s atmosphere in the flashes of light that are called meteors. Most intriguing are the outbursts that occur at times unrelated to the return of the comet to perihelion, and it is

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suspected that these might be and techniques are being developed Astrophysical Studies and flew a associated with long-period comets. to find more in order to study their CDP-capture experiment early this It remained unclear whether the properties. year (October 1995 to February outbursts were caused by a trail of 1996) as part of the European Point of Contact: P. Jenniskens dust in the path of these comets or Exposure Facility’s Comrade experi- (650) 604-3086 by clouds of dust in orbits with a ment on the Russian Mir space [email protected] shorter orbital period. No observa- station. Two small capture cells/ tions made with standard meteor modules each 9 by 5 by 1.5 centi- observing techniques had been meters thick were flown, recovered, successful, until FY96. and returned to Ames on March 25, It was proposed that the plan- Capturing Cosmic Dust 1996. One of the two aerogel etary motions affect the orbits of on Mir capture modules was exposed from particles, causing Earth to periodi- early October 1995 until early cally traverse the trail of dust. The Kenji Nishioka, Ted Bunch, February 1996; the second capture return of one such stream in Novem- Mark Fonda, Glenn Carle, module was exposed for only ber of 1995 was predicted. Condi- Sherwood Chang, James Ryder, 10␣ days during the Orionids shower tions would be favorable to measure Janet Borg in October 1995. These capture cells the orbital period of the particles were the first aerogel experiments to As part of exobiology’s effort to over Europe and Africa, where it was fly on Mir. The results of preliminary night at the expected time of the solve the quintessential question of analyses of the capture modules are how life started on Earth, it is event, and the point from which the summarized below. Strict proce- necessary to have information meteors radiated would be high in dures were followed in handling the the sky, allowing good viewing. A concerning the prehistoric origin and modules to ensure that any changes evolution of biogenic elements and network of photographic and image- detected, including contamination, compounds from the interstellar intensified TV systems was set up in would be a result of the environment Andalusia, Spain, operated princi- medium that coalesced into the solar around Mir, from shipping of the system. Interplanetary and cosmic pally by amateur observers of the modules (packing material), or from dust particles (IDPs/CDPs) are Dutch Meteor Society. captured particles. The outburst did indeed occur believed to have survived from that Physical (visual) examinations early period largely unchanged; as a and was confirmed by many observ- of the modules were done in a result, they may shed light on the ers in Europe. Meteor rates increased 10,000 class clean room. When the briefly to five meteors per minute. chemical pathways taken by the module covers were removed, the biogenic elements and their com- Most of the meteors were too weak integrity of the module/aerogel was pounds in moving from their origins to be photographed. A rare color verified; it had survived shipping, image is shown in the figure (see in stars and the surrounding media launch, orbital exposure, and to their incorporation into planetary Color Plate 15 in the Appendix). Ten recovery without apparent structural bodies such as Earth. Thus the meteors were recorded from mul- problems, except for stretching of tiple sites and triangulation of their interest to capture contamination- the platinum retainer wires. This free cosmic dust particles. paths allowed the reconstruction of probably resulted when entrained air Ames Research Center, the SETI the orbit of the particles. The in the aerogel could not escape particles had a long orbital period, Institute, and Lockheed Martin quickly enough to equalize the Missiles and Space have developed confirming that this meteor outburst internal pressure and the rapidly ultrapure aerogel, containing about was due to a trail of dust in the wake decreasing external pressure during of a long-period comet. Identifica- one part per million carbon, for launch, thus causing the aerogel to contamination-free capture of CDPs tion was made of 14 such streams bulge and the wires to stretch. The in Earth orbit. This group joined with that produce occasional outbursts cosmetic surface blemishes on the the University of Paris’s Institute for

P ROGRESS IN EXOBIOLOGY 81 aerogel surface reported in the 1995 strongly suggesting the possibility of peptides—possible precursors of Research and Technology Report, an orbital debris particle or other enzymes and receptors. Unfortu- appeared noticeably darker and source of contamination. nately, short peptides typically have rougher, whereas the clear unblem- Valuable insights were gained disordered structures in aqueous ished surfaces appeared unaffected into the manufacturing, fabrication, solution and, therefore, do not in the recovered modules; this was and use of aerogel for building a appear to be suitable for the desired later confirmed by microscopic successful IDP/CDP capture instru- cellular functions. However, at examination. These initially blem- ment from this flight experiment. water-membrane, water-oil, or ished areas are probably susceptible Aerogel is robust and holds together water-air interfaces, many of these to ozone oxidation. even under IDP/CDP impact, and peptides, depending on their While in the clean room, surface under launch and ground handling sequence, can acquire a broad range and subsurface aerogel samples loads. Also, aerogel does not appear of well-defined secondary structures, were taken from the modules for susceptible to the migration of such as a-helix, b-strand, or b-turn. analyses. Organic chemical analyses surface contaminants. But as A crucial, common characteristic of of the aerogel surface samples expected, the experiments gave rise these interfaces is that a nonpolar showed high contamination levels to new questions. For example, phase is adjacent to water. (2%) of dioctyl adipate, a plasticizer. where did the high concentration The ability of small peptides to This was unanticipated, and there of dioctyl adipate come from? Do organize at aqueous interfaces was are no reports of this contaminant as particles, especially at the micron or examined by performing a series of an orbital experiment concern in the tens of micron size, survive capture, large-scale molecular dynamics literature. Additional samplings from and how will these micron-size computer simulations of several the modules confirmed the high particles and their tracks be found peptides. The peptides were com- contamination levels. Interior and analyzed cost effectively? posed of two amino acids, nonpolar samples showed that the contamina- leucine (L) and polar glutamine (Q), Point of Contact: K. Nishioka tion did not migrate and was con- in a variety of environments; they (650) 604-0103 fined to the surface. differed in the size and sequence of [email protected] An automated microscopic the amino acids. Among the mol- scanning system at the University of ecules studied were the dipeptides California at Berkeley was used to LL, LQ, QL, and QQ. Although these scan the modules for impacts. peptides were too short to form a Several candidate impact points with Simple Peptides at secondary structure, they are very tracks were found and are being Water-Membrane good models for use in examining analyzed by an x-ray probe tech- the conformational preferences of nique at Brookhaven National Interfaces the peptide backbone as a function Laboratory. Preliminary x-ray Andrew Pohorille, Christophe Chipot of the sequence and the environ- fluorescence spectra results from the ment. The studies of L/Q peptides x-ray probe of a track failed to detect Even the simplest protocell must were extended to include two particulate matter at the end of the have had the capability to catalyze heptamers, of sequence LQQLLQL track. But, the “chondritic” elements the chemical reactions needed for its and LQLQLQL. The sequences were calcium (Ca), iron (Fe), nickel (Ni), survival and growth and to commu- designed to maximize the interfacial manganese (Mn), titanium (Ti), and nicate with its environment. These stability of the a-helix and b-strand chromium (Cr) were found in the functions must have been accom- conformations, respectively, by track and could indicate the breakup plished by simple molecules that exposing polar side chains to water of a pyroxene particle; however, could have been present in a and nonpolar side chains to a small amounts of lead (Pb), zinc protobiological milieu. One such nonpolar phase. (Zn), copper (Cu), strontium (Sr), and group of potential early catalysts and Finally, a transition of an zirconium (Zr) were also found, signaling molecules were the undecamer (11 residues), composed

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entirely of leucine residues, from a backbone angles but also in confor- nonpolar phase. As demonstrated by disordered structure in water to an mations of side chains. Once folded, the example of the leucine a-helix in a nonpolar phase, repre- the peptides form structures that are undecamer, such peptides fold into senting the interior of the membrane, suitable for polymerization and have an a-helix as they partition into the was investigated. This is the first time the potential for catalytic activity. nonpolar medium (see the two that the complete folding of a If peptides consist of nonpolar figures). The folding proceeds peptide in solution was accom- residues only, they insert into the plished in computer simulations. The simulations revealed several basic principles governing the sequence-dependent organization of peptides at interfaces. Understanding these principles allows for determining how peptides could have performed protocellular functions. Short peptides tend to accumulate at interfaces and acquire ordered structures, provided that they have a proper sequence of polar and nonpolar amino acids. The specific identity of amino acids appears to be less important, which is a desirable protobiological property. The dominant factor determining the interfacial structure of peptides is the hydrophobic effect, which is manifested at aqueous interfaces as a tendency for polar and nonpolar groups of the solute to segregate into the aqueous and nonpolar phases, respectively. The resulting structures are called amphiphilic. Exceptions from this tendency are observed only when intramolecular hydrogen bonds are formed in the nonpolar phase without completely removing polar side chains from water, a unique feature of interfacial systems. Based on the results for folding the LQQLLQL heptamer to an a-helix at the water surface, it is Fig. 1. Polyleucine undecamer interacting with the water-hexane interface proposed that, whenever possible, at t = 0 nanoseconds. The center of mass of the peptide is located peptides fold at interfaces through a approximately 11 angstroms from the water-hexane interface. In water, the series of amphiphilic intermediates. structure of the peptide is disordered. The atoms of the polyleucine are dark Transitions between these intermedi- gray, the oxygen and hydrogen atoms of water are medium gray and white, ates involve changes not only in respectively, and the CH2 and CH3 segments of hexane are light gray.

P ROGRESS IN EXOBIOLOGY 83 simple mechanism for transmitting signals from the environment to the interior of a protocell.

Point of Contact: A. Pohorille (650) 604-5759 [email protected]

Silicon-Micromachined Gas Chromatography System Thomas Shen, James Suminto, Frank Yang, Daniel Kojiro, Glenn Carle

The development of gas chro- matographic equipment for planetary atmospheric probes and soil gas or pyrolytic analysis was required for both the Viking mission to Mars and the Pioneer Venus mission. A gas chromatography (GC) instrument was used for the Pioneer Venus mission. However, future missions, such as the Mars Exploration Mis- sions and missions to probe the atmospheres or moons of the outer planet, will require further reductions in equipment weight, volume, Fig. 2. Polyleucine undecamer interacting with the water-hexane interface and power requirements. at t = 40.2 nanoseconds. The peptide has folded into an a-helix, and the NASA is in a very dynamic peptide backbone vector makes an angle of about 20° with the normal to mode at this time. A massive effort is the water-hexane interface. The color scheme is the same as described under way to revolutionize the in Fig. 1. technical approach to spacecraft and robotic exploration. The Discovery Program is the first of these new through an intermediate conforma- to perpendicular, especially in approaches. Other programs follow- tion, called a 310-helix, which response to local electric fields. ing it include New Millennium, remains in equilibrium with the The ability of nonpolar peptides to Micro-spacecraft, and Nanoinstru- a-helix. Once in the nonpolar modify both their structure and ments. All of these enterprises have environment, the peptides can orientation with changing external in common the requirement for readily change their orientation with conditions may have provided a better, faster, cheaper. Clearly, respect to the interface from parallel current technology will not likely be feasible for future space studies.

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Nitrogen Sources and .04 Detector #6 Sinks on Early Earth Detector #5 David P. Summers Detector #4 .03 One important form of fixed and reduced nitrogen on early Earth is ammonia. However, current .02 geochemical evidence points to a nonreducing atmosphere which

Current (mA) contains nitrogen (N2) instead of ammonia. One source of ammonia .01 involves the formation of nitrite – (NO3 ) which can then be reduced to ammonia by ferrous iron (Fe+2). It has also been suggested that this 0 0 100 200 300 400 500 cannot be an important source of Voltage (V) ammonia since nitrite can react with ammonia (to make nitrogen). Fig. 1. Discharge curves of micromachined chips. Whether this is true, however, depends on how the kinetics of the reactions involved compare with the A silicon-micromachined GC on the chip with the new in-house- speed of other sources and sinks for system in which the detector and developed highly efficient silicon both ammonia and nitrite. If the column are integrated into a small polymer material (U.S. patented) will reaction of nitrite with ammonia is piece of silicon has been studied by be modified and coated to separate slow compared with other processes several researchers. The problem is most chemical components. This that make and destroy ammonia, that no sensitive detector has been small and highly sensitive GC system then it will not be important. Any designed and tested. A proposal was will be able to meet future mission evaluation of the importance of made to use the matastable ioniza- requirements. various sources and sinks of nitrite tion detector principle, and replace In this first year of the project, and ammonia, and of whether the radioactive material with the several micromachined chips with ammonia is likely to be present in glow discharge method, which has different electrode designs were significant amounts, requires an not been studied on the silicon- prepared and tested. The preliminary analysis of all the kinetic processes micromachined GC system. A very devices were produced by Micro- affecting those species. narrow discharge distance can be Tech Scientific Inc. Several chips Using a kinetic analysis of rate produced and controlled, a helium have been evaluated. The discharge data that had either been measured ionization detector can be produced, curves of these chips are demon- at Ames or were already published and a highly sensitive analysis can strated in the figure. in the literature, a kinetic analysis be obtained (concentrations below was performed to establish what the Point of Contact: T. Shen the parts-per-million level can be concentrations and rates might have (650) 604-5769 detected) through a micromachined been in the early ocean. Plausible [email protected] silicon wafer. In addition, a column sinks/sources for nitrite and ammonia on early Earth are: the reduction of nitrite to ammonia, the reaction of nitrite with ammonia, photochemical destruction of either nitrite or

P ROGRESS IN EXOBIOLOGY 85 ammonia, and destruction at hydro- 3␣ x 10–8 and 2 x 10–6 molar, respec- bombard planetary rings, generating thermal vents. The photochemical tively. The very low nitrite concen- ejecta which transport mass and destruction of nitrite depends on tration reflects the fact that the nitrite angular momentum in systematic trace species that can react with is reduced to ammonia before it has ways throughout the system. An photo-generated hydroxy radicals a chance to build up or undergo any exhaustive study, which fully models and on the amount of ultraviolet competing processes. The concen- the entire range of bombardment, light, neither of which is known for tration is such that its importance for transport, and mixing effects by certain to have existed on early many processes envisioned for the which highly absorbing “primitive” Earth. Furthermore, the product of origin of life (like the formation of interplanetary material pollutes and photolysis, nitric oxide (NO), is the amino acids) is unclear. redistributes material in an initially same compound that nitrite (and This is part of a broader question pristine icy system such as Saturn’s hence ammonia) is formed from. of whether life would have started rings, has been completed. The Therefore, values for rates of photo- in the open ocean, where dilution study includes careful treatment of chemical destruction probably makes the formation of more the fate of ejecta particles as they fly represent only an upper limit. complex species difficult, or some- about within a realistic radial profile Ammonia can also be lost by where where a means of concentra- of ring particle abundance, and also adsorption into clays. However, this tion species (such as with vesicles detailed radiative transfer modeling, will be significant only when the or by evaporation) is present. In using actual material refractive ammonium concentration is high general, concentration would tend to indices of the individual ring particle enough to compete with potassium raise the concentration of all species, reflectivity as a function of wave- and serves mostly to limit the rather than change the relative length and location in the rings. concentration below an upper limit importance of the source and sinks The model implies (1) that with of 10 millimolar. (except where species are not most parameters of the model Under most conditions, the allowed to be photolyzed or swept constrained by other observations, primary sink for nitrite is reduction into hydrothermal systems). it is found that the basic global to ammonia. Destruction at hydro- brightness and color differences Point of Contact: D. Summers thermal vents is important at acidic between the major ring regions (650) 604-6206 pH’s and close to the freezing point (A-ring, B-ring, C-ring, etc.) can be [email protected] of water. The reaction between understood for the first time, and in a ammonia and nitrite is not an simple way, by differential darkening important sink for either nitrite or caused by the infall of spectrally ammonia. Photochemical destruc- Progress PROGRESS in IN Planetary PLANETARY Systems SYSTEMS neutral, highly absorptive, probably tion, even in a worst case scenario, carbonaceous, meteoritic material is unimportant under many condi- with orbits much like those of tions but could be important under Planetary Rings comets; (2) that the “initial,” primor- acidic, high carbon dioxide (CO2) Jeff Cuzzi dial composition of the rings is pressure, or low-temperature almost entirely water ice, but must conditions. The primary sink for Planetary ring and moon contain a uniformly distributed, ammonia is photochemical destruc- systems, especially the magnificent highly red, probably organic mate- tion in the atmosphere. Under acidic Saturn system, contain elements of rial such as is found in “primitive” conditions, more of the ammonia is processes in particle disks that bodies in the outer solar system and tied up as ammonium (reducing its provide insights into planetary in Titan’s organic atmospheric haze vapor pressure), and hydrothermal formation. Saturn’s rings will be a (silicates are not acceptable as destruction becomes more impor- main focus of study for the Cassini coloring agents); (3) that the radial tant. At 25°C, pH 7.6, and 0.2␣ atmo- mission, to be launched in October profile of ring particle color (and sphere of CO2, nitrite and ammonia 1997. Interplanetary meteoroids thus compositional) variations have steady-state concentrations of provides a good fit to the model

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profiles for a range of exposure equations are averaged, and new that a certain key descriptor of the times which is in agreement with terms appear as a result of particle multifractal (the so-called singularity exposure-time estimates from damping, which has been modeled spectrum) is Reynolds-number bombardment effects on radial using a gradient-diffusion-type independent. variations of ring structure; and approach. Quantitatively, the density-field (4)␣ that nominal parameters for the In FY96, several different singularity spectrum agrees with that model imply a ring age of the order parameterizations for dissipation of for turbulent dissipation, perhaps of 100 million to 1 billion years, turbulence by the gas itself, which providing some profound clues depending on the ejecta yield and has a major effect, were compared. toward explaining this very impor- the meteoroid flux, indicating that A two-length scale model, a law-of- tant process. It is now feasible to the rings may not be as old as the the-wall model, and two variable make use of extensive mathematical solar system (4.5 billion years). eddy-frequency models were techniques developed for fractal explored; few really significant analysis to predict the probability Point of Contact: J. Cuzzi differences in model behavior were density of particle concentration at (650) 604-6343 found between these parameteriza- arbitrary Reynolds numbers, [email protected] tions. Significant damping of nebula strengthening the applicability of turbulence does occur, to a degree these results to plausible nebulae that is particle-size dependent, but with Reynolds numbers that are the damping effect is not sufficiently orders of magnitude higher than are Planetesimal Formation in strong to allow the particle layer to achievable numerically. settle into a gravitationally unstable the Protoplanetary Nebula Point of Contact: J. Cuzzi dense midplane layer as some prior (650) 604-6343 Jeff Cuzzi workers had speculated. This [email protected] appears to be one of the first fully The “primary accretion” coupled, physically parameterized process—the process by which the studies of turbulence damping by first sizable objects (comets, aster- mass loading—certainly this is so in oids, etc.) formed from solids that the context of an orbiting disk. PASCAL: A Mars Climate entered the protoplanetary nebula as Three-dimensional direct micron-sized dust motes—is one of Network Mission numerical simulations of particles in the major unsolved problems in turbulence have been exhaustively Robert M. Haberle, David C. Catling, understanding the origin of planetary analyzed. The Taylor microscale Steven C. Merrihew systems. One key accomplishment Reynolds number ranges from 40 to this year was the completion of a 140, and the code handles one Of all the planets in the solar new model of self-consistent turbu- system, Mars is most like Earth. In million particles at each of 16 Stokes lence generation and damping, by particular, its weather and climate numbers (the Stokes number is the thin, dense layers of large (10-cm ratio of particle stopping time to are dynamically similar to Earth’s. radius and larger) particles in the Mars therefore offers a natural Kolmogorov eddy turnover time). midplane of a protoplanetary laboratory for the study of the factors Previously, it was demonstrated that nebula. Prior studies neglected the the particle size most strongly that control a planet’s climate role of the particles in damping system. Yet the kind of observations concentrated (by orders of magni- turbulence in the gas; a scheme to that are needed to carry out such a tude) is in good agreement with account for this effect has been chondritic meteoritic data. This year, study, namely long-term simulta- developed and implemented. The neous measurements from a network it has been demonstrated for the first scheme begins with the Reynolds- of globally distributed surface time that the particle density field for averaged equation for the turbulent the most strongly concentrated stations, are lacking in NASA’s Mars kinetic energy. The full two-phase exploration program. To remedy particle size is a multifractal—and

P ROGRESS IN PLANETARY SYSTEMS 87 this, a Mars climate network mission the surface. This aspect of the The Center for Star was proposed in response to the 5th mission will be particularly valuable Announcement of Opportunity to for future Mars orbiters which plan Formation NASA’s Discovery Program. This to aerobrake into their final orbits. D. Hollenbach, P. Cassen mission was named PASCAL after PASCAL would be launched in the 17th century French scientist April of 2001 and arrive at Mars in The Center for Star Formation whose name is synonymous with January 2002. The 6.8-kilogram Studies, a consortium of scientists the Système International unit of probes would be released from a from the Space Science Division at pressure. spin-stabilized carrier on direct Ames and the astronomy depart- Pressure is the key measurement approach to Mars. To achieve global ments of the Universities of Califor- of the PASCAL mission. It provides a coverage, the probes would be nia at Berkeley and Santa Cruz, measure of the total mass in a released in salvos of eight, each conducts a coordinated program column of air. Given information on separated by a propulsive time-of- of theoretical research on star and its horizontal and temporal variation arrival adjustment to allow Mars to planet formation. The Center one can infer the nature of the rotate underneath. Entry descent and supports postdoctoral fellows, senior planet’s general atmospheric circula- landing would utilize a heat shield, a visitors, and students; meets regu- tion and climate system. Fortunately, parachute, and crushable material larly at Ames to exchange ideas and pressure is also easy to measure, and for final deceleration. One possible to present informal seminars on pressure sensors do not require network configuration resulting from current research; hosts visits of orientation or deployment. Thus, this deployment scheme is shown in outside scientists; and conducts a very simple landers can be designed the figure (see Color Plate 16 in the week-long workshop on selected that are light and robust. In effect, Appendix). aspects of star and planet formation we are trading off the ability to make To ensure long lifetimes, each of each summer. many different kinds of measure- PASCAL’s surface stations would be The Star Formation Summer ments at a few sites, for just a few powered by a Light Weight Radio- Workshop in 1996 was held at measurements at many sites. This isotope Heating Unit (LWRHU) Wellesley College in Wellesley, trade allows us to achieve the global coupled to a thermoelectric con- Massachusetts, and included, in coverage that is required to observe verter. The LWRHU also provides addition to the Ames scientists, the planet’s climate system while thermal control for the surface about 100 astrophysicists from all keeping the total mission cost well stations. Communication would over the world. within the Discovery cap. occur through one of the orbiters of The main focus of work in FY96 PASCAL’s mission objective is to the Mars Surveyor Program (MSP). was on the collapse of dense clouds establish a network of 24 globally MSP plans to have orbiters at Mars to form protostars with protoplane- distributed surface stations that will beginning in September 1997 and tary disks, the evolution of these measure hourly variations in pres- continuing well into the next disks, which ultimately form planets, sure and temperature over a period century. As a safety precaution, and the influence of young massive of 10 Mars years (~18.8 Earth years). however, PASCAL’s landers are stars on the surrounding star-forming This long-term continuous presence capable of storing up to 5 Mars years molecular cloud. D. Hollenbach, will define the nature and variability of data should an orbiter not be A.␣ Tielens, and M. Kaufman mod- of the planet’s climate system on available. eled the thermal structure and time scales ranging from hours to spectra of dense molecular clouds Point of Contact: R. Haberle years. It will also provide a weather which are collapsing to form high (650) 604-5491 monitoring infrastructure for future mass stars. A similar calculation was [email protected] Mars missions. In addition to made by C. Ceccarelli (University of network science, PASCAL will gather Grenoble), D. Hollenbach, and data on the structure of the atmo- A.␣ Tielens for clouds collapsing to sphere as each probe descends to form low-mass stars. When the

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model spectra are compared with and the cessation of star formation of the innermost Jovian energetic observations, observers can identify in the cloud. D. Hollenbach and trapped proton fluxes, made with the collapsing clouds and measure the H.␣ Stoerzer modeled these pro- Pioneer 10 and 11 spacecraft, as rate at which the protostellar mass is cesses, incorporating a large well as provide data from the region increasing. D. Hollenbach and numerical code which followed even closer to the planet that had D.␣ Neufeld (Johns Hopkins Univer- the time-dependent chemistry, the not yet been directly traversed by sity) calculated the heating and thermal balance, and the transport of spacecraft. Beginning at 3 hours ionization created when the collaps- radiation. Their models predict the before atmospheric entry, inside the ing cloud hits the protoplanetary infrared spectra from such regions, orbit of Io, and until entry, the disk. Comparisons of the models so that observations can be inter- experiment sampled the energetic with recent radio observations of preted quantitatively in terms of the trapped particle environment. Flux hot, ionized gas surrounding a rates of these destructive processes. measurements and energy spectral nearby protostar made it possible to These theoretical models have and angular distribution data for determine the rate of mass accretion been used to interpret observational energetic electrons and protons were onto the disk and the mass of the data from such NASA facilities as the obtained. central protostar. K. Chick and Infrared Telescope Facility, the The electron fluxes appear to P.␣ Cassen developed models to Kuiper Airborne Observatory, and be within a factor of 3 of values explain the survival of presolar the Infrared Astronomical Observa- obtained by earlier experiments material during the formation of the tory, as well as data from numerous aboard Pioneers 10 and 11, at solar system, as dust particles in the ground-based radio and optical locations where comparisons could collapsing molecular cloud eventu- telescopes. In addition, they have be made. Except nearest to the ally incorporate into primitive been used to determine require- atmosphere, where the energy meteorites. ments for future missions such as spectrum steepened considerably, Once formed in the collapse, the Stratospheric Observatory for the most probable measured elec- protoplanetary disks around solar- Infrared Astronomy and the pro- tron energy was about 20 and type stars evolve for millions of years posed Space Infrared Telescope 40␣ million electron volts, respec- as they form planets. K. R. Bell and Facility. tively, for each of two separate P. Cassen examined the shapes of electron-energy thresholds, based Point of Contact: D. Hollenbach protoplanetary disks and demon- principally on energy-dependent (650) 604-4164 strated how the temperature depen- responses for the experiment [email protected] dence of the effective grain opacity deduced from Monte Carlo simula- can lead to configurations in which tions. Energetic-proton fluxes, much of the disk is shadowed from spectra, and angular distributions the central star. B. Pickett, P. Cassen, were measured in three separate and R. Durisen (Indiana University) Energetic Trapped energy ranges in the 42 to used three-dimensional hydrody- Particles near Jupiter ~131 million electron-volt energy namic simulations to show how the range. The proton fluxes were development of gravitational insta- John D. Mihalov observed to decrease abruptly bilities in the early stages of proto- inward from the location of Jupiter’s On December 7, 1995, the planetary disks is controlled by the ring, and also as Jupiter’s atmo- radiant energy losses. Galileo Probe carried experiments sphere was approached. into Jupiter’s atmosphere, near the Young massive stars radiate Future analyses of the decreases planet’s equator. The experiment copious amounts of ultraviolet in particle fluxes measured as the radiation, which heats, dissociates, complement included an energetic- atmosphere was approached may particle telescope supplied by a and ionizes the surrounding molecu- give insight into the structure of group at the University in Kiel, West lar cloud, and which ultimately Jupiter’s near-equatorial upper leads to the dispersal of the cloud Germany. Data from this experiment could improve earlier measurements

P ROGRESS IN PLANETARY SYSTEMS 89 atmosphere, because the energetic NASA Ames Research Center and Time-Dependent particles lose energy as they interact the Statistics Department of Stanford with atmospheric constituents while University through Joint Research Structures in Galaxies they drift around the planet and Interchanges, and was funded by the Bruce F. Smith, Richard A. Gerber, bounce along the magnetic field. In NASA Astrophysics Data Program Richard H. Miller, addition, atmospheric interactions of and Astrophysics Software and Thomas Y. Steiman-Cameron the electrons are characterized by Research Aids Program. The author Coulomb scattering that causes collaborated with David Donoho Numerical experiments on diffusion of mirror points along of the Stanford and U.C. Berkeley models of galaxies are yielding new magnetic field lines. Some energetic Statistics Departments on this insights into galactic structures and trapped helium, in the 62 to project. The actual software is in the dynamics. This research is designed 136␣ million electron-volt per form of MatLab (copyright the to examine time dependencies in the nucleon energy range, evidently was MathWorks, Inc.) scripts, which can structural components of galaxies detected outside Jupiter’s ring. be easily translated to other systems. and to determine the implications for The World Wide Web site, both the structural and dynamical Point of Contact: J. Mihalov maintained at Stanford (http:// evolution of galaxies. The results of (650) 604-5516 playfair.Stanford.EDU:80/~wavelab/) these investigations are being used [email protected] includes downloadable software for in interpreting and understanding Unix, Macintosh, and Windows high-resolution observations of computers, complete documenta- galaxies made by the Hubble Space tion, tutorials in basic and advanced Telescope (HST) and other advanced Wavelet Software wavelet transform methods, sample observational programs. A series of numerical experiments has been Jeff Scargle data, and browser routines for exploring the sample data. made on the Cray C90 and parallel machines at the Numerical Aerody- Wavelets are a mathematical The WaveLab system has been namic Simulation (NAS) Facility at tool for the analyzing and interpret- downloaded by several thousand Ames Research Center to understand ing time series, images, and other persons who have registered their the nature of time-dependent datasets. New wavelet-based use of this free, public-domain processes in galaxies. These experi- methods, developed for scientific software, many of whom have ments probed the nature of complex and engineering applications, are indicated that they have already motions observed at the centers of useful for the following: (1) Charac- found WaveLab useful for their galaxies including those seen at the terizing the physical processes research, teaching, or commercial center of our Galaxy. underlying complicated temporal enterprises. The developers answer Global oscillatory modes have and spatial variations; (2) removing questions and help with user also been seen in the numerical unwanted observational noise from problems by e-mail. experiments. These n-body experi- data; (3) compressing data with only Point of Contact: J. Scargle ments provided the first experimen- insignificant loss of information; (650) 604-6330 tal evidence of long-lived global (4)␣ probing computer models for [email protected] oscillatory motions in spherical physical processes that have a large systems. These oscillations have dynamic range. been identified as normal modes; A powerful suite of wavelet the entire galaxy rings like a bell. algorithms to implement all these Several modes have been identified, ideas has been developed and made but two are dominant and both are publicly available under the name spherically symmetrical. The first is “WaveLab.” WaveLab was a coop- nearly a homologous contraction erative research project between

90 P ROGRESS IN PLANETARY SYSTEMS S PACE SCIENCE ENTERPRISE

and expansion of the entire galaxy systems are not uncommon and Philadelphia, Pennsylvania, built (the fundamental mode; a “breath- might be explained by the interac- the probe’s heat shield. NASA’s Jet ing” mode), and the second has one tion of a disk with an oscillating Propulsion Laboratory, Pasadena, node. A detailed study of the effects halo. As the evolution proceeds a California, built the Galileo orbiter of softening in the representation of bar develops in the inner disk (see spacecraft and manages the overall the potentials in the calculations has second figure (see Color Plate 18 mission. verified the earlier results on long- in the Appendix)). Many galaxies, The ratio of helium to hydrogen lived global oscillations. including our own, have bars in their by mass is a key piece of information Given that the normal-mode central regions. in theories of planetary evolution. oscillations persist over many For the Sun, this value is about 25%. Point of Contact: B. Smith dynamical time scales, a natural Comprehensive analysis of results (650) 604-5515 question is: What processes could from the probe’s helium-abundance [email protected] give rise to the oscillations? Among detector have shown that the helium the possibilities are that (1) the abundance for Jupiter is near 24%, oscillations could be left over from about the value for the primordial the galaxy formation process, Sun. (2)␣ they may be initiated by inter- Galileo Encounters The Jovian helium abundance actions with neighboring galaxies, Jupiter: Results from the indicates that gravitational settling of or (3) they could grow from helium toward the interior of Jupiter instabilities. Probe has not occurred nearly as fast as it These global oscillatory modes Richard E. Young apparently has on Saturn, where the may play an important role in the approximate helium-to-hydrogen structure and evolution of disk/halo The cone-shaped Galileo probe ratio is just 6%. This indicates that galactic systems. The approach has entered the atmosphere of Jupiter on Jupiter is much hotter in its interior been to assume that a significant December 7, 1995, at a speed of than its neighbor Saturn, the next fraction of the mass in a galaxy is in over 106,000 miles per hour and largest planet in the solar system. It a dark halo. The halo oscillates and survived deceleration forces of also may cause scientists to revise the luminous disk material responds 228␣ times Earth’s gravity. After their estimates of the size of the to these oscillations. In the numeri- deploying a parachute, it relayed rocky core believed to exist deep in cal experiments the disk responds data to the Galileo orbiter space- the center of Jupiter. to the time-varying potential by craft, which was overhead, for The abundances of several developing a ring structure that 57.6␣ minutes. At the same time, the heavy elements, including carbon, forms and disappears during each Galileo orbiter began a 2-year, nitrogen, and sulfur, are significantly oscillation cycle (see first figure (see 11-orbit tour of Jupiter. So far it has greater on Jupiter than on the Sun. Color Plate 17 in the Appendix)). had close flybys of the Galilean This implies that the influx of This pattern of response persists over moons Ganymede, Callisto, and meteorites and other small bodies time periods approaching a Hubble Europa. The images it provides have into Jupiter over the eons since its time (assumed age of the Universe spatial resolutions 10–100 times formation has played an important since the big bang). The response better than the Voyager images. role in Jupiter’s evolution. can be understood as a resonance of The Galileo probe project is However, minimal complex the stars in an annular region where managed by NASA Ames Research organic compounds were detected, the disk epicycle frequency is the Center. Hughes Space and Commu- indicating that such complex same as the halo oscillation fre- nications Co., El Segundo, Califor- combinations of carbon and hydro- quency. This appearance of the ring, nia, designed and built the probe. gen are rare on Jupiter and that the or annular gap, is reminiscent of Lockheed Martin Hypersonic chances of finding biological activity some S0 galaxies (disk-like struc- Systems (formerly General Electric), there are extremely remote. tures), such as NGC 4513. Such

P ROGRESS IN PLANETARY SYSTEMS 91 The winds, determined from amount of water much less than that substantial vertical exchange tracking of the probe, persisted deep of the Sun. between the atmosphere and the below the clouds, strongly suggest- The probe’s instruments found regolith could explain the results. In ing that heat escaping from deep in much less lightning activity on collaboration with Bruce Jakosky at the planet’s interior drives the winds, Jupiter per unit area than on Earth. the University of Colorado, it was rather than solar heating. Since all Lightning on Jupiter was found to be found that nighttime inflections in the outer giant planets exhibit strong about one tenth of that found on the atmospheric temperature record winds, scientists hope that under- Earth in an area of the same size. at the Martian surface could be standing Jupiter’s winds will lead to Although there is less lightning explained by the condensation of important new insights into their activity, the individual lightning H2O in the atmosphere, at a frost unusual meteorology. events are, however, about 10 times point which supports the model of The Galileo probe apparently more energetic than similar events diurnal H2O exchange. entered Jupiter’s atmosphere near on Earth. Point of Contact: A. Zent the southern edge of a so-called Point of Contact: R. Young (650) 604-5517 infrared hot spot, which is believed (650) 604-5521 [email protected] to be a region of reduced clouds. [email protected] The probe’s nephelometer (an instrument used to study suspended particles) observed only one distinct cloud layer, and that a tenuous one The Nature of the Martian by Earth standards. It is likely to be Regolith Effects on Mars’ Oxidants an ammonium hydrosulfide cloud. Climate Three distinct cloud layers (an upper Aaron Zent layer of ammonia crystals, a middle Aaron Zent In FY96, laboratory analysis of layer of ammonium hydrosulfide, and a thick bottom layer of water In FY96, analysis of the adsorp- the ability of hydrogen peroxide tion of water on Martian analog (H O ), complexed by the Ti4+ and ice crystals) were expected. 2 2 materials at Mars-like conditions was cation, was completed to reproduce There were, however, some indica- tions from the probe net flux radiom- completed. In laboratory experi- the results of the Viking biology ments, it was discovered that the experiments. It was discovered that eter and nephelometer that the mass of adsorbed H O was approxi- the results of the Labeled Release probe started taking direct measure- 2 ments in the bottom part of Jupiter’s mately an order of magnitude less experiment, in which organic than previously predicted. These molecules were oxidized by a top ammonia ice cloud layer. results were used to derive new temperature-labile oxidant in the Further analysis of probe data has confirmed the preliminary report adsorption isotherms which reflect soil, could be reproduced by outer- the heterogeneity of the surface sites sphere (that is, with an intervening that the Jovian atmosphere appears on Martian (or any) soil. hydroxyl radical (OH) group) to be relatively dry, with much less water than anticipated on the basis In collaboration with Howard peroxo-Ti complexes. The ability of Houben at Ames, these new iso- inner-sphere (that is, no intervening of solar composition and on predic- therms were applied to the study of OH group) complexed H O to tions from data sent by the Voyager 2 2 spacecraft that flew by Jupiter in the transport of water by the Martian reproduce the Gas Exchange experi- atmosphere. It was found that the mental reactivity and stability pattern 1979. These studies predicted a horizontal advection of water by is still being investigated. water abundance for the planet of twice the solar level (based on the the Martian atmosphere could not Also explored was the role of reproduce the observed patterns of the diffusion of H O into the Sun’s oxygen content.) Actual probe 2 2 atmospheric H O variations, but that Martian regolith, and the role of measurements now suggest an 2

92 P ROGRESS IN PLANETARY SYSTEMS S PACE SCIENCE ENTERPRISE

impact gardening in redistributing effect of background gases on the ketones, aldehydes, and polymers oxidized material through the proposed array of coatings will be which are of particular interest from Martian regolith. One finds that for investigated. a prebiotic perspective. The ready reactive half-lives of the order of formation of these complex organic Point of Contact: A. Zent 100,000 years, diffusion will carry species from simple starting mixtures (650) 604-5517 the oxidant into the upper 20 meters and the ice chemistry that ensues [email protected] of the Martian regolith; also impact when these ices are warmed suggest cratering will stir this material that interstellar ices and comets may throughout the upper 100 meters of have played an important part in the the regolith, necessitating deep Progress in Astrophysics origin of life. drilling if unoxidized material is to PROGRESS IN ASTROPHYSICS In addition to cometary ices be recovered. raining a rich inventory of poten- Astrobiology in the tially important prebiotic molecules Point of Contact: A. Zent down onto early Earth, the com- (650) 604-5517 Astrochemistry Laboratory pounds in cometary ices may also [email protected] Louis J. Allamandola, Scott Sandford, have played a role in early mem- Max Bernstein, Robert Walker, brane production. Formation of Dave Deamer membranes is considered a critical step in the origin of life, for they are The Ames Astrochemistry required to isolate and protect the A Thermo-Acoustic Laboratory has made major contri- interior workings of a cell from the Oxidant Sensor butions to the understanding of the surrounding medium. Within the composition and properties of Aaron Zent confines of a membrane, conditions interstellar and cometary ices. This is such as acidity can be moderated done by studying laboratory analogs In FY96, an investigation was and held at a different value from begun into the feasibility of using a of cometary and interstellar ices. An that in the surrounding medium, thermo-acoustic oxidant sensor to important application of this work to nutrients can be concentrated, and the origin of life is reported here. identify and quantify the nature of so on. Although it is uncertain where atmospherically produced oxidants Since comets are considered to be membrane formation falls in the in the Martian atmosphere. A series a major source of the molecules sequence of events leading up to the brought onto primitive Earth before of selective chemical coatings, origin of life, it is considered an including lead sulfide, metal phtha- life began, their organic composition absolutely crucial step. When the locyanines, and peroxidase are is of central importance to questions most complex organic molecules concerning the origin of life. placed on chemiresistors and surface produced by irradiation of the acoustic-wave devices. The mode of Cosmic ices contain the very simple mixed molecular ices are measurement for the chemiresistors simple molecules, water (H O), 2 placed in water, water-insoluble methanol (CH OH), carbon monox- is resistivity change owing to 3 droplets form naturally. This self- bonding between the measure and ide (CO), carbon dioxide (CO ), 2 organizing, lipid-like behavior is the coating; for the acoustic-wave molecular hydrogen (H ), ammonia 2 similar to that found for the organic (NH ), and formaldehyde (H CO), devices it is mass changes of the 3 2 components of the Murchison same coating. Sensitivity to hydro- as well as more complex species. meteorite. The figure shows micro- gen peroxide, ozone, and carbon Ultraviolet irradiation of these ices graphs of these nonpolar droplets. produces other simple species such monoxide is demonstrated. Both photographs are of the same In collaboration with Dr. Marc as H , H CO, CO , CO, methane 2 2 2 field of view, with the upper photo- Madou of the University of Califor- (CH ), formyl radical (HCO), and 4 graph taken in normal light (yellow- more complex organic molecules nia at Berkeley, flight electronics for ish cast) and the lower in fluorescent this experiment are being developed. known as amides, nitriles, amines, In the coming year, the crosstalk and

P ROGRESS IN ASTROPHYSICS 93 emission stimulated by a black light (ultraviolet light). The upper photograph shows the presence of two distinct phases, liquid water and insoluble droplets. Several of the self-organized droplets show intriguing structures suggestive of cell walls. In comparing the upper and lower photographs, it is interesting to note that all of the larger and many of the smaller droplets have trapped blue photoluminescent material also produced by the original ice irradiation. The ability to trap energy receptors within these structures is also considered a critical step in the origin of life, for it provides the means to “power” the protocell, as photosynthesis does today in plants.

Point of Contact: L. Allamandola (650) 604-6890 [email protected]

Spectrum Synthesis of Hot Water in Sunspots and Selected Cool Stars Duane F. Carbon, David Goorvitch

The objective of this research is to define the energy distribution of late-type stars so that their physical state is better known. Better informa- Fig. 1. Photomicrographs of the water-insoluble droplets formed when a few tion about their physical state will drops of water are placed on the most complex molecules produced by then lead to improved abundance irradiation of an interstellar and cometary ice analog. Both photographs determinations and energy stan- show the same field of view, with the upper photograph taken in natural dards. Very recently, Partridge and lighting and the lower in fluorescence stimulated by ultraviolet. Taken Schwenke of Ames Research Center together, these photographs show that the self-organizing droplets form completed an elaborate theoretical naturally from these materials and that they also trap luminescent materials computation of the potential-energy in their structures. surface and dipole moment function for H2O. They have used their results to predict the positions and

94 P ROGRESS IN ASTROPHYSICS S PACE SCIENCE ENTERPRISE

strengths of nearly 308 million A High-Altitude Site technique, so it has good vertical 1H1H16O lines. This line tabulation resolution, but relatively poor is the most complete now available. Survey for SOFIA horizontal resolution. The cloud- It extends to sufficiently high excita- Michael R. Haas, Leonhard Pfister frequency data have been vertically tions so that the spectra of M-stars integrated above 41,000 feet and (cool red stars) may be modeled The Stratospheric Observatory averaged over the three summer with greater accuracy than ever for Infrared Astronomy (SOFIA) will months (June, July, and August) for a before provided the predicted line have a 2.5-meter telescope mounted 6-year period. Part (b) of the figure parameters of Partridge and in the aft section of a Boeing 747 SP shows the total frequency of cloud Schwenke are themselves accurate. for use in making astronomical occurrence for summer as measured Synthetic sunspot spectra have observations at wavelengths by the High-Resolution Infrared been computed using the Partridge between 0.3 and 1600 microns. Radiation Sounder (HIRS) sensors on and Schwenke H2O line list and the This study investigates the meteoro- polar orbiting National Oceanic and sunspot umbral models. In order to logical conditions above 41,000 feet Atmospheric Administration satel- test the new line list, a careful and finds that there are significant lites since June, 1989. Since this comparison of these synthetic weather patterns at these altitudes satellite is nadir-looking, this dataset spectra and of published high- which can adversely affect airborne has much better horizontal resolu- resolution sunspot atlases has been astronomy. tion, but a significantly higher carried out. This comparison shows Experience has shown that high- minimum optical depth and poorer that the new H2O line list success- altitude cloud cover and water-vapor vertical resolution. fully predicts the sunspot H2O overburden are the most important Water vapor is the principal spectrum and that it can specify meteorological factors affecting the molecular absorber throughout where further improvements in the quality of astronomical observations much of the infrared. Its strong line tabulation are necessary. In at typical flight altitudes. To deter- vertical stratification at altitudes addition, as part of this study, it is mine acceptable home base sites for below the tropopause is one of the demonstrated that sunspot atmo- SOFIA, these factors must be mea- primary motivations for conducting spheres are much cooler in their sured over broad geographic airborne observations from the shallow layers than predicted by the regions, since a typical flightpath stratosphere, where the water-vapor models and that the most recent line covers hundreds of kilometers. The overburden is relatively small and tabulation for the OH molecule is only source of such data is satellites constant. Furthermore, the negative seriously in error. which provide global coverage of temperature gradients just below Using the new H2O tabulation, Earth over an extended period of the tropopause allow rapid vertical the extent to which hot stellar time. transport of moisture. When com- water blankets the H (1.65 microns), This study gathers the best bined with low, upper tropospheric K␣ (2.20 microns), and L available satellite data, shows that temperatures, this results in the (3.45 microns) passbands for they corroborate airborne experi- formation of extended, thin sheets selected K- and M-star model ence, and demonstrates that they are of cirrus clouds. Part (c) shows the atmospheres and, thus, the energy consistent with well-known global average tropopause height for the distribution of these stars, is also circulation, convection patterns, summer season, and part (d) shows investigated. and upper-tropospheric/lower- the water-vapor overburdens in stratospheric dynamics. Part (a) of precipitable microns as inferred from Point of Contact: D. Carbon the figure (see Color Plate 19 in the the Microwave Limb Sounder (MLS) (650) 604-4413 Appendix) shows the total frequency for the summers of 1992 and 1993. [email protected] of cloud occurrence as measured by Although the positive temperature the Stratospheric Aerosol and Gas gradient above the tropopause Experiment (SAGE II). This instru- strongly increases the vertical ment uses a limb occultation stability of the atmosphere and

P ROGRESS IN ASTROPHYSICS 95 places a lid on the rapid vertical and conveying this objective to change in brightness the planet size transport of moisture in Earth’s students and the public, an educa- can be calculated, and the mass and atmosphere, there are clearly large tional software package has been surface gravity can be estimated. variations from this simple model. developed and distributed publicly. The software package has The largest variations in high- Experience with educators has several components, including the altitude weather over the United shown a demand not just for infor- following: States occur in the summer because mation, but also for science data that ␣ ␣ 1.␣ ␣ A description of the latest results the tropopause is near 41,000 feet. students could analyze. This has in the search for planets beyond our Moreover, different portions of the been a difficult challenge, since in own solar system; United States lie in different meteo- general the latest data from airborne ␣ ␣ 2.␣ ␣ A description of a habitable rological regimes in terms of large- and space-borne experiments almost planet, one where liquid water may scale circulation and the potential always requires sophisticated data be found on the surface; for convection. The eastern Pacific is processing and an “educated eye” ␣ ␣ 3.␣ ␣ A description of the various dominated by the downward motion to glean the subtle effects being methods, including the capabilities associated with the mid-Pacific observed. However, the observations and limitations of the different upper-level trough, and by generally to be performed by the Kepler detection techniques; lower sea surface temperatures. East Mission, which has been proposed ␣ ␣ 4.␣ ␣ A description of the Kepler of a line extending from northern to the Discovery Program, to detect Mission, the only currently practical Mexico along the Rockies into Earth-sized planets are based on a method for finding Earth-sized Canada, there is upward motion straightforward principle that can be planets; associated with the continental easily understood even by upper ␣ ␣ 5.␣ ␣ An interactive Kepler Mission upper-level ridge. Warm moist air elementary students. An interactive simulator; from the Gulf of Mexico, and to a software package has been devel- ␣ ␣ 6.␣ ␣ A biography of Johannes Kepler, lesser extent from the Gulf of oped that allows the students to both a description of his three laws of California, promotes convection east perform simulated observations as if planetary motion, and information of the Rockies and in northwestern they were the astronomers and then on his life and times. Mexico. Moffett Field, the site to analyze the data to determine the The software is written in selected for SOFIA operations, is habitable properties of the planet. Hyperstudio™ for the Macintosh, well within the regime of downward The Kepler Mission␣ has been and the Hyperstudio™ player is motion which results in lower upper- proposed as a Discovery Mission to included. The software can be level cloudiness and lower water- search for habitable planets. The downloaded from the Kepler Mission vapor overburdens. purpose of the mission is to continu- web site (WWW.kepler.arc.nasa.gov). ously and simultaneously observe When compressed, the entire Point of Contact: M. Haas 160,000 stars for evidence of software package with the player is (650) 604-5511 planetary transits. When a planet 1␣ megabyte and will fit on a single [email protected] passes in front of its star it causes the high-density disk; thus it is easy for star to dim. When a second transit of teachers to copy it and carry it into the same duration and with the same the classroom. Use of the software brightness change occurs, the exact does not require an Internet Kepler Mission orbital period can be predicted. connection. When additional transits are seen, Educational and Public Point of Contact: D. Koch one has a high confidence that a (650) 604-6548 Outreach Software planet has been detected. From the [email protected] David Koch period, the orbital distance of the planet from its star can be calculated In response to the strategic goals and the characteristic temperature of finding other habitable planets of the planet estimated. From the

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Mid-Infrared Studies of sensitivities that were orders of true both for those regions located magnitude better than any instru- within the plane of the galaxy and Diffuse Interstellar mentation previously used for diffuse for those regions above the galactic Material mid-infrared emission studies. plane. The remarkable similarity of Thomas L. Roellig The first data from the MIRS the spectra from the different regions have now been analyzed and have indicates that there is little chemical Infrared observations of the yielded interesting new information differentiation between these emission from material located in about the interstellar material. The regions. The spectral features the diffuse regions of space between observed mid-infrared interstellar themselves are indicative of emis- the stars can provide important emission was found to be concen- sion from a class of hydrocarbons— information on its composition and trated almost solely in a few emis- polycyclic aromatic hydrocarbons energy state. This information is sion bands (see the figure). This was (PAHs). In the scenario envisaged to crucial to our understanding of star formation and galactic evolution. Unfortunately, such observations are × 10Ð6 W mÐ2 srÐ1 very difficult, largely because this 14 emission is very weak and is easily drowned out by infrared radiation emitted from the telescope optics. 12 Furthermore, many of the most interesting regions in the infrared spectrum are obscured by absorption 10 in Earth’s atmosphere. ) λ F

As a result, a telescope in space λ cooled to temperatures only a few 8 degrees above absolute zero is needed for these investigations. Such a telescope, optimized for infrared 6 studies of diffuse regions, was flown

in 1995 in a NASA/Japanese Space Surface brightness ( Agency collaboration—the Infrared 4 Telescope in Space (IRTS) infrared survey mission. The Mid-Infrared Spectrometer (MIRS), an instrument 2 developed and operated jointly by NASA Ames and the University of Tokyo, was attached to the IRTS and 0 operated over wavelengths ranging 4 5 6 7 8 9 10 11 12 from 4.6 to 11.7 microns. This is an Wavelength (µm) ideal spectral region for investigations of infrared emission from solid Fig. 1. Spectra obtained from the Mid-Infrared Spectrometer on the Infrared material, since it covers many of the Telescope in Space mission. For all spectra, the galactic longitude was diagnostic stretching and bending approximately 50°. The different lines correspond to different galactic modes of candidate interstellar latitudes, b. The solid line indicates emission from -0° 40’ < b < 0°, the material. The IRTS/MIRS telescope/ dashed line emission from 1° < b <2°, the dotted line emission from instrument combination achieved 2° < b < 3°, and the dot-dashed line emission from 3° < b < 5°.

P ROGRESS IN ASTROPHYSICS 97 operate in the interstellar medium, Infrared Observations of there is a long thin “Arc,” also called these molecules absorb ultraviolet the Straight Filaments, that crosses photons and then emit this energy in G0.18-0.04 the Galactic Plane at right angles. the infrared. The spectra obtained by Janet P. Simpson, Sean W. J. Colgan, The length and thinness of the the MIRS show that the mid-infrared Angela S. Cotera, Edwin F. Erickson, synchrotron radiation emitting Arc emission from the diffuse regions in Michael R. Haas, Mark Morris, (and other arcs not in the figure), the galaxy can be attributed almost Robert H. Rubin suggest that the Galactic Center solely to this material. The MIRS region has a strong magnetic field; data also show that the previously Radio images of the center of however, the excitation and source unexplained excess emission our Galaxy show a number of of the relativistic electrons emitting observed in the mid-infrared by the features that are unique in the the synchrotron radiation is not earlier Infrared Astronomical Satel- Galaxy and that are very difficult to known. lite (IRAS) mission can be attributed explain. Some of these are demon- The Galactic Center H II region, to these emission bands. strated in the figure, which is a G0.18-0.04, also called the “Sickle,” Interestingly enough, a compari- 20-cm Very Large Array radio image is located where the Arc crosses the son of the spatial distribution of by F. Yusef-Zadeh and M. Morris, Galactic plane. The Sickle appears these mid-infrared emission features overlaid with contours showing the to be the ionized edge of the dense with the emission at the much locations of the Galactic Center molecular cloud whose contours are longer wavelength of 100 microns molecular clouds. A quarter of a shown in the figure. In the past, the observed with the Infrared Astro- degree from the Galactic Center source of ionization of the Sickle has nomical Satellite mission indicates a very close correlation. Since the 100-micron emission is not expected to arise from PAHs, but instead from ° Galactic plane much larger grains of solid material, Ð28 40' this tight spatial correlation must E2 mean that these two different kinds Arched of interstellar materials are mixed in 45' filaments a constant ratio throughout the G0.18Ð0.04 W2 different interstellar regions in 50' E1 the galaxy. Pistol H5 GO.095+0.012

Point of Contact: T. Roellig Declination (650) 604-6426 55' H2 [email protected] Straight A B filaments C1 Sgr A C2D Sgr A WEST Ð29° 00' 10 pc F E G

45m30s 17h43m0s 42m30s 42m0s Right ascension

Fig. 1. The 20-cm Very Large Array radio image, overlaid with contours showing the locations of the Galactic Center molecular clouds. Sgr A is the Galactic Center. G0.18-0.04 (the Sickle) and the Pistol are labeled.

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been ascribed to both the interaction extinction is fairly uniform over the and interface region between the of the cloud with the magnetic field region and is consistent with a cloud and H II region are also of the Arc and to the hot stars in the location in the Galactic Center. consistent with heating and excita- adjacent star cluster, AFGL 2004, There is no indication of the dense tion by the same stars. The electrons also known as the “Quintuplet molecular cloud that had previously in the Arc probably originate in the Cluster.” There is a smaller region of been suggested by other researchers ionized gas of the H II region and thermal gas known as the “Pistol”; to lie between Earth and the region are excited to relativistic energies the star cluster AFGL 2004 lies in the images of the star field. The by magnetic reconnection of the between the Sickle and the Pistol. previous suggestion of excitation of magnetic field lines of the Arc and Because of the great obscuration the Sickle by interaction of the the molecular cloud. toward the Galactic Center, it is not molecular cloud with the magnetic Point of Contact: J. Simpson possible to see these regions at field required that the cloud, which (650) 604-1613 wavelengths visible to the eye; recedes at 25 kilometers per second [email protected] instead, one must use infrared and away from Earth, produce the radio telescopes to view the region. observed 20- to 120-kilometers-per- The objective of this study is to second ionized gas in the H II region ascertain the relative locations of the by running into the magnetic flux stars, the ionized and molecular gas, tubes of the Arc. Thus, both the Arc New 3.405-Micron and the sources of gas excitation and and the ionized gas would be on the Interstellar Emission from dust heating. far side of the cloud from Earth in Far-infrared lines of C+, N+, this scenario. Since the near-infrared Organic Hydrocarbons N++, O0, O++, Si++, and S++ were measurements of the stars and the Gregory C. Sloan, Jesse D. Bregman measured with the Cryogenic ionized gas demonstrate that the gas Grating Spectrometer on the Kuiper must be on the near side of the Polycyclic aromatic hydrocar- Airborne Observatory. For the H II cloud, this early suggestion cannot bons (PAHs) are a form of organic region, electron densities for both be correct. hydrocarbon identified by their the O++ and S++ zones were The observed lines were com- complex spectral emission in a rich estimated, and abundance ratios pared with predictions of models of variety of astronomical sources. This were calculated for O++/S++, N++/ slab H II regions ionized by a cluster spectrum includes several emission O++, N+/N++, N+/O++, Si+/S++, of luminous stars. This comparison features between 3 and 13 microns, and S++/H+. For the less excited gas indicates that the source of ioniza- originally described as the unidenti- in the interface region between the tion of the Sickle is probably the hot fied infrared emission features. Louis H II region and the molecular cloud, stars of the AFGL 2004 cluster, but Allamandola and his Ames collabo- the incident photon flux and densi- the Pistol has a lower ionization than rators identified the carriers of this ties were estimated from the C+ its proximity to the cluster would spectrum by their laboratory analysis and O0 lines and the far-infrared suggest. More likely, the Pistol is of PAHs. These molecules typically continuum. ionized by the extremely luminous consist of 20-50 carbon atoms Near-infrared images of the star that the Ames researchers found arranged in a flat matrix of aromatic region were taken by A. Cotera as to be located near the center of its rings, with hydrogen atoms bonded part of her Stanford University Ph.D. arc. Since the positions at some to the carbon on the edge. The thesis (1995), supported by a NASA distance from AFGL 2004 have C-H bonds produce most of the Graduate Student Research Fellow- higher ionization than is predicted spectral features observed from ship at Ames. From the 1.65 and by the models, it is likely that there the ground; stretching modes 2.1␣ micrometer photometry of stars are additional hot stars scattered produce features at 3.3 microns and in the field and from the Hydrogen throughout the region. The low nearby; bending modes produce Br gamma images, the extinction to excitation lines and far-infrared features at 8.6 microns and in the the region could be estimated. The continuum from the molecular cloud

P ROGRESS IN ASTROPHYSICS 99 11.2–12.7-micron region. These ultraviolet field is destroying the Bernstein et al. analyzed what they organic molecules may represent PAHs there. They decrease into the describe as H-PAHs, or PAHs with more than 15% of all interstellar molecular region because the additional H atoms attached to the carbon, so a better understanding of ultraviolet flux which excites the carbon on the periphery of the their composition would give us spectral features is being attenuated PAHs. These atoms convert aromatic insight into the evolution of interstel- by the high optical depths of the C-H bonds to aliphatic C-H bonds, lar carbon material. Because PAH neutral and molecular gas in the Bar. producing an emission feature at spectra are seen in so many sources, In general, these features decrease 3.395 microns, as well as the PAH a better understanding of the emis- into the molecular region exponen- plateau and emission feature at sion mechanisms would make them tially, with a 1/e scale height of 3.51 microns. In fact, their labora- very powerful probes of the interstel- approximately 10 arcseconds. tory spectrum of hexahydropyrene lar medium. However, the PAH plateau, and the provides the closest match yet PAH spectra are observed 3.40- and 3.51-micron features show attained to the astronomical PAH typically at the edge of ionized a layer of enhanced emission spectrum. regions. One such region, the Orion roughly 10 arcseconds behind the The evidence is growing that the Bar, is a transition region between ionization front, right where emis- 3.40-micron feature arises from an the Orion Nebula, ionized by the sion from H2 also peaks. This aliphatic C-H bond. Both of the ultraviolet energy from the Trape- enhancement is especially notice- components at 3.40 microns that zium, and the molecular cloud to able in the 3.40-micron emission we have identified arise from such a the southeast. These transition feature. bond, although the bond resides in regions have strong gradients in A careful analysis of both the different carriers. Based on the ultraviolet flux decreasing from the shape and the strength of the differences in spatial behavior ionized zone to the molecular 3.40-micron feature reveals that it between these components, it region. The Bar presents the observer actually consists of two spectrally appears that the methyl sidegroups on Earth with an edge-on geometry and spatially distinct components. are easily destroyed beyond the which makes it an excellent labora- The main component peaks at molecular hydrogen emission layer, tory to study how PAH emission 3.395 microns and behaves spatially whereas the H-PAHs survive right up varies with excitation conditions. very similarly to the PAH plateau to the ionization front. The 3-micron PAH emission in and the 3.51-micron feature. The Point of Contact: J. Bregman the Orion Bar was observed using a secondary component peaks at (650) 604-6136 long-slit spectrometer at the United 3.405 microns, and its emission is [email protected] Kingdom Infrared Telescope in concentrated 10 arcseconds behind October 1995. These spectra allow the ionization front, again, right one to trace the strength of the where the H2 emission peaks. 3.29-micron PAH feature, which The spectral properties can be dominates the spectrum and arises interpreted in terms of recent from a ground-state aromatic C-H laboratory analyses of PAHs at stretch; the weaker features observed NASA Ames by Bernstein, Sandford, at 3.40 and 3.51 microns; and the and Allamandola and by Joblin, underlying emission plateau which Tielens, Allamandola, and Geballe. stretches from 3.3 to 3.6 microns. Joblin et al. analyzed PAHs with These features peak on the ioniza- attached methyl sidegroups, which tion front, and drop in strength into contain aliphatic C-H bonds and both the ionized and molecular produce an emission feature close regions. The features decrease into to the position of the secondary the ionized region because the harsh component, 3.405 microns.

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Progress PROGRESS in IN Space SPACE TechnologiesTECHNOLOGIES theorem-proving within a formal allocation. A preliminary PVS model model can be used to generate test of the scheduler and interrupt cases for testing the actual system handler functions has also been Assessment of the Cassini being modeled. The union of formal developed. Command and Data models with test-case generation will Point of Contact: E. Addy help to alleviate the difficulty of Subsystem (304) 367-8353 maintaining fidelity, and will provide Edward A. Addy [email protected] useful information in the form of test cases to the development team. Formal methods have been The functioning of the scheduler promoted as an effective means of and interrupt handler through developing software that requires a analysis of the Cassini Command high degree of assurance. Yet to Automatic Telescope and Data Subsystem (CDS) source date, formal methods have not Project code has been used as a case study. significantly affected software A formal model of this part of the John Bresina development practices. The difficulty CDS software was created, using the of maintaining the fidelity of the The primary objective of the formal specification language, formal model with the system as the Automatic Telescope Project is to Prototype Verification System (PVS), system undergoes changes in which is based on a classic, typed provide advanced scheduling and requirements and specifications automation infrastructure so that the higher-order logic. The PVS system during development has contributed benefits and performance of single- includes support tools and a theorem to its failure to influence the devel- prover. This follows on from previ- user automatic telescopes can be opmental practices. The goal of this made available to a large commu- ous research in which formal model project is to determine if the use of nity of users, with no additional checking was used to generate test cases for the actual system. The test people in the loop. In addition, Web-based assistance is provided data and the model checking have for “service observing,” which is been used jointly to maintain the Formal model fidelity of the model with the actual becoming the dominant operations mode for large-scale, sophisticated Model checking system as it is being developed. This telescopes. The benefits are a Theorem proving project has used theorem-proving within the formal model in a similar dramatic reduction in telescope operating costs and an increase in fashion, to generate test cases for the both scientific productivity and ease- CDS and to increase the fidelity of Test cases Test data the model to the CDS, as illustrated of-use. The Associate Principal Astronomer (APA) enables electronic in the figure. request submission, automatic The source code from the System Cassini CDS related to the scheduler loading and scheduling, and electronic data return, all under the Requirements and interrupt handler functions was Specifications control of a single astronomer (see Implementation analyzed. The formal modeling process identified that the millisec- the figure for an illustration of the architecture). The advanced loading ond interrupt was not functioning and scheduling techniques provide properly. The development team Fig. 1. Use of theorum-proving in modified the scheduler, improving fair allocation of telescope time and support high-quality data collection. generating test cases to maintain its performance and eliminating the The APA software tools have formal model fidelity during system potential for improper memory development. been extensively tested by G. Henry at Tennessee State University (TSU)

P ROGRESS IN SPACE TECHNOLOGIES 101 APA

Scheduler Health monitoring Loader APA

Data base Network negotiator PA interface

APA

Data reduction PA

ATIS receiver ATIS sender

APA

Astronomers

Fig. 1. Associate Principal Astronomer architecture.

and by the Fairborn Observatory testing on the UK Infrared Telescope of the SOA at UKIRT and demon- staff. The scheduler has been (UKIRT). There was enthusiastic strated the system to senior staff of executing nightly since January 1996 reception of the APA from UKIRT, the multinational Gemini project for Fairborn telescope T8. The loader the Hands-On-Universe project, the (and others). has been undergoing nightly testing Four College Telescope, and UK’s Point of Contact: J. Bresina for the same telescope since April New Generation Astronomical (650) 604-3365 1996, and the Service Observing Telescopes Project. John Davies [email protected] Associate (SOA) is undergoing carried out a successful “live test”

102 P ROGRESS IN SPACE TECHNOLOGIES S PACE SCIENCE ENTERPRISE

Guide Star Tracker for (1.87␣ kelvin) in order to accommo- thermal disturbances must be kept to date the gyroscope readout detectors a minimum. Gravity Probe B Relativity of the Superconducting Quantum The Space Technology Branch Mission Interference Device (SQUID). has contributed to the star sensor John H. Goebel Because both the gyroscope and development effort for GPB by guide telescope are rigidly mounted assisting in the design, construction, The guide star tracker for the together in the liquid-helium-cooled development and testing of the Gravity Probe B (GPB) Relativity portion of the satellite, the starlight photodiode and cooled electronics. Mission is used to define the inertial sensing detectors and preamplifier This effort is a collaboration with reference frame against which the electronics must function without scientists and engineers at Stanford relativistic effects of a satellite in a disturbing either the gyroscopes or University, Marshall Space Flight polar Earth orbit can be measured. the telescope wavefront. Tracking Center, Goddard Space Flight The tracking telescope is cooled to accuracy of the order of 10␣ milliarc- Center, Ames Research Center, superfluid helium temperature seconds is required, implying that Lockheed-Martin Corporation, and various suppliers of component parts. A photograph of the Revision B hybrid electronics circuit for the star sensor that is mounted in the cryogenic vacuum vessel is shown in the figure. The sensor has been demonstrated to meet the requirements for functioning in the cryogenic environment by operating at a somewhat elevated temperature of 70 kelvin with a power dissipation not exceeding 2 milliwatts. Opera- tion of the sensor at temperatures down to 30␣ kelvin has been demonstrated at power dissipation less than 1␣ milliwatt.

Point of Contact: J. Goebel (650) 604-3188 [email protected]

Pulse-Tube Cryocooler Development Fig. 1. Revision B Hybrid Circuit. This circuit is 0.400 inches in diameter Peter Kittel and includes two circular silicon photodiodes and four square silicon field effect transistors. Light from the guide star is focused on the detectors which Pulse-tube coolers have unique convert the light to electrical current which in turn is amplified by the advantages over the other coolers transistors. The circuit is thermally isolated from the cryogenic environment that are usually considered for NASA so that it can operate at an elevated temperature of 70 kelvin. space missions. Because they have

P ROGRESS IN SPACE TECHNOLOGIES 103 no moving parts in the cold part of the cooler, they have inherently very long lifetimes and very low levels of vibration. However, they are a Orifice relatively new technology and Pulse tube Regenerator require further development to Compressor Reservoir achieve the thermal efficiency of Cold junction more mature coolers such as Stirling Fig. 1. Components of a pulse tube-cryocooler. coolers. The first figure shows the main components of a pulse-tube cryocooler. absorbing temperature oscillations conditions that were similar to those The compressor (at room and allowing adequate flow. that would exist in actual use. These temperature) provides an oscillating The behavior of this region of measurements showed that the gas pressure which moves gas into the cooler has been difficult to pressure drop at frequencies near and out of the cooler. The regenera- predict; measurements of pressure 60␣ cycles per second was 20–30% tor consists of a tightly packed bed drop with oscillating flow have less than that predicted from steady- of fine screens that absorb any disagreed with predictions based flow data. These improved data temperature oscillations in the gas. on steady-flow data. Therefore, (shown in the second figure) will The compressor end of the regenera- measurements were made to charac- allow much better optimization of tor is at room temperature and the terize the screen mesh of the regen- the regenerator screens. other end is cold. The pulse tube erator under oscillating flow isolates the cold junction from the orifice and reservoir at room temperature. A properly adjusted orifice creates a special relationship between the pressure oscillations in 100 the pulse tube and the gas flow such that heat is drawn from the cold junction and deposited at the orifice. In FY96 great progress was made in understanding and improv- 10 ing the operation of two of the main Friction factor Steady flow data components of the cooler—the regenerator and the orifice. For the screen mesh in the Various amplitudes regenerator to adequately absorb 60 Hz data temperature oscillations in the gas 1 passing through it, it must have a large surface area and a large mass. 1 10 100 These requirements suggest a large Reynold’s number number of very fine screens and a high impedance to the gas flow. The Fig. 2. Pressure drop in a 325-mesh regenerator. Solid curve is steady-flow regenerator must not be too restric- data. The data points are the instantaneous pressure drop during 60-cycle tive, because this would reduce the runs for a variety of amplitudes. pressure and flow available for cooling at the pulse tube. It is crucial to find the best compromise between

104 P ROGRESS IN SPACE TECHNOLOGIES S PACE SCIENCE ENTERPRISE

The orifice serves to adjust the Automated Space System New Millennium Program relationship between oscillating gas Autonomy Technical Integration pressure and gas flow in the pulse- Experimental Testbed Experiments concerning data tube section. An analysis of the Project distribution, principal investigator system shows that much more Christopher Kitts interfacing, beacon operations, cooling power could be obtained if ground system automation, and fault sufficient adjustment of this relation- The Automated Space System management. ship could be achieved. However, Experimental Testbed (ASSET) Point of Contact: C. Kitts the range of adjustment available project is an Internet-based, justified- (650) 604-0149 from a simple orifice is not enough operations control system for small [email protected] to allow the utilization of the extra satellites. The project’s objective cooling power that the system is was to establish a global spacecraft capable of. What is needed is a control network in order to (1)␣ pro- device that has “inertance” in vide operational support for a variety addition to the dissipation of the of low-cost missions, and (2) provide Amphion and orifice. To use an electrical analogy, a high-risk, low-inertia testbed for Meta-Amphion the “resistance” represented by the validating spacecraft autonomy Michael Lowry orifice needs to be replaced by a strategies. device with “inductance.” A device The operational system provides Most of today’s programming with the inertance needed turns out an automated link between a variety problems involve a programmer to be a long narrow tube; typically it of users (including principal investi- building special domain-oriented would be 2-3 millimeters in diam- gators, students, operators, and the software libraries (modules that eter and several meters long. public) and a multitude of spacecraft perform a specific function) for every Preliminary testing has been payloads. The ASSET system is domain. Then users must make performed with such an inertance capable of accepting goal-level software program calls to these tube in place of the orifice, and the experimental parameters and modules in order to get the work cooler performed considerably better planning and scheduling system and done. The correctness of these than it did with the orifice; this spacecraft activities, and of conduct- programs is difficult to prove. shows that the analysis is on the ing mission and health-related Amphion automates the use of these right track. More improvement is tracking, telemetry, commanding software libraries. It enables a user expected as understanding of the operations with the spacecraft, and to state a problem in an abstract, operation of the inertance tube is delivering the experimental data to graphical visual programming gained and its parameters are the original experimenter. To do this, notation, rather than requiring the optimized. the ASSET system components user to construct a solution by include a central mission control Point of Contact: P. Kittel manually composing software center, geographically distributed (650) 604-4297 components. Amphion then auto- ground stations, a variety of space- [email protected] matically generates a program craft, Internet and HAM radio consisting of calls to the library communications links, and numer- components to solve a specific ous payload components. problem. Moreover, as part of this ASSET provided an unparalleled generation process, which is done opportunity for rapid experimenta- through automatic theorem-proving, tion with revolutionary autonomy Amphion produces a mathematical technologies in a real-world, com- proof that the program is correct. plex space system. The initial ASSET Formal mathematical methods are implementation is supporting the

P ROGRESS IN SPACE TECHNOLOGIES 105 code level to the declarative, specification level. The generic Amphion system is nearly mature, having gone through an extensive alpha/beta version that has already been tested by customers.

Point of Contact: M. Lowry (650) 604-3369 [email protected]

Focal-Plane Sensor Array Development for Astronomy in Space Mark E. McKelvey, Robert E. McMurray, Jr., Craig R. McCreight

A team at Ames Research Center is evaluating the suitability of a number of detector and readout- device technologies for space- Fig. 1. Amphion-generated science-opportunity visualizer for the infrared astronomy applications. This Cassini Mission. program aims to foster development of focal plane array (FPA) detector technology that will allow reliable background-limited infrared (IR) applied for program verification. If details of the components in a astronomy from space-based plat- performed manually, this formal software library. This removes a forms such as the Space Infrared proof is costly and only becomes significant barrier to the use of Telescope Facility (SIRTF). Advances cost-effective for safety-critical NASA’s software libraries. The figure in microelectronics to provide systems. shows a snapshot of a science- operation of low-noise, low-power Meta-Amphion is a system that opportunity visualizer for the Cassini devices in the radiation environment will enable software-library develop- Mission. The code for the visualizer found in Earth orbit are keys to the ers to create and maintain their own was generated automatically by success of this program. specialized Amphion systems. In Amphion. Evaluations of state-of-the-art essence, Meta-Amphion is the next- The benefit of Meta-Amphion is Impurity Band Conduction (IBC) generation application-generator to enable the widespread develop- focal plane detector arrays produced technology. Using Amphion, it takes ment of specialized Amphion by several manufacturers are con- on average an order of magnitude systems, thus realizing the dual tinuing for applications in the less time for a user to develop a benefits of automated formal meth- 5–30-micron wavelength range. domain-oriented problem specifica- ods and domain-specific automatic These detectors rely on a thin, highly tion than to manually generate and programming. Meta-Amphion is the doped IR-active layer to provide debug a program. Equally important, set of tools and infrastructure needed a user does not need to learn the to elevate programming from the

106 P ROGRESS IN SPACE TECHNOLOGIES S PACE SCIENCE ENTERPRISE

difference in radiation-damage susceptibility between similar arrays from different manufacturers. This damage is manifested as dose- dependent activation of dark current that could be of crucial importance to the Wide-Field Infrared Explorer (WIRE) or SIRTF science missions. The results of the Ames tests are being fed directly back into the manufacturing process in order to help advance the state of the art. Improved IBC devices from a joint Ames/Santa Barbara Research Center development are presently being evaluated. These 256 × 256 arrays utilize a simplified unit cell architecture and new sampling techniques to achieve read noise levels as low as 12 equivalent electrons. These devices are prototypes for the flight detectors to be used on the SIRTF Infrared Array Camera (IRAC). The Ames group will continue to play an important role in the definition and execution of the × Fig. 1. 256 256 element infrared detector array. IRAC detector acceptance and qualification test program. Other recent efforts involve high quantum efficiency from a sensitive to IR wavelengths as long hardware and software upgrades to small detector volume, minimizing as 28 microns can be reliably the suite of test instrumentation the ionization cross section for produced. maintained in the detector labora- cosmic ray events. A high-purity Work in FY96 was concentrated tory. Recent upgrades have allowed blocking layer prevents excessive on evaluating the performance of easier manipulation of the data files dark current, despite the high doping large-format (to 256 × 256 detector collected from these large-format levels in the IR-active layer. IBC elements; see figure) state-of-the-art detector arrays. A project is presently arrays also exhibit wider spectral IBC detector arrays in simulated under way to enhance the capability response than alternative photo- on-orbit radiation environments, of the data acquisition system to conductor (PC) architectures, using the 76-inch Crocker Cyclotron handle arrays as large as 1024 × without many of the performance on the campus of the University of 1024 elements. Continuous software anomalies associated with PC California at Davis to provide a high- development has provided improved devices. IBC architectures are well energy proton beam for device test flexibility, automation, and suited to modern epitaxial fabrica- testing. These tests, in collaboration repeatability. Work on maturing IBC tion methods, and the technology with astronomers from Cornell technology and improved readouts, has progressed to the point where University and from the University of along with other sensor technologies large-format hybrid FPAs that are Arizona, have shown a marked

P ROGRESS IN SPACE TECHNOLOGIES 107 in ongoing efforts, will enhance space missions. We are currently FY96 accomplishments include overall IR focal-plane performance grounding the research by develop- completion of the rapid prototyping in NASA space- and ground-based ing the smart executive, part of the effort in November 1995, demon- applications. Remote Agent (RA) being developed stration of the prototype, and for the Deep Space One (DS1) presentation of the smart executive Point of Contact: M. McKelvey mission, part of NASA’s New to the NMP in the December 1995 (650) 604-6643 Millennium Program (NMP). DS1 Technology Readiness Review, [email protected] will autonomously navigate to which accepted the RA architecture asteroids and comets and will be to be developed for the DS1 mission. able to achieve its mission in the Point of Contact: B. Pell face of a wide variety of faults, (650) 604-3361 Intelligent Execution for including total loss of control from [email protected] Autonomous Spacecraft Earth. As an integrating technology, an Barney Pell executive enables each software component to be expressed indepen- An executive system is an event- dently, but it controls the interac- New Millennium Program driven and goal-oriented agent tions among those components so Deep Space 1 Flight that␣ coordinates run-time activity that the overall activity of the system among a set of components involved Software Program achieves global constraints as in a control system. As such, it dictated by a high-level plan. This Management provides a language and a frame- dramatic increase in modular Scott Sawyer work in which software designers software design reduces develop- can express how planning, control, ment and integration costs and The New Millennium Program’s diagnosis, and reconfiguration increases software reuse both within Deep Space One (NMP DS1) Flight capabilities are to be integrated into and across missions. The goal- Software team comprises staff from an autonomous system. It can directed task-decomposition auto- Ames and the Jet Propulsion Labora- request and execute plans involving mates much of the labor-intensive tory (JPL) (which also includes concurrent activities among sub- sequencing process in spacecraft individuals from the Air Force systems, in the presence of uncer- operations. This capability also Phillips Laboratory, TRW, Carnegie- tainty in the success, timing, or enables a new generation of adap- Mellon University, and Thinkbank, outcomes of activities. A smart tive controllers, in which different Inc.). The team is developing flight executive provides a language for control modes are developed that software (FSW) for the first mission expressing goal-decompositions and are switched by a smart executive of the New Millennium Program resource interactions. When inter- based on feedback from the (NMP). The Ames team (along with preting this language at run-time, the environment. part of the JPL team) is dedicated to executive automates the decomposi- The DS1 mission will validate developing and testing the “Remote tion of goals into smaller activities the smart executive and the entire Agent” architecture of the FSW. The which can be executed concur- RA in the context of actual space remote agent (RA) integrates rule- rently, thus automating aspects of flight. The architecture will serve as and model-based fault detection, the labor-intensive sequencing the baseline for the next generation isolation, and recovery; advanced function in spacecraft operations. of space missions, and will be planning and sequence management This task investigates the deployed to a wide variety of capabilities; and a system executive development of increasingly intelli- manned and unmanned spacecraft; that serves as an autonomous agent gent execution systems, their role in it will also increase the level of controlling and coordinating the autonomous control systems, and autonomy in other control systems, satellite’s behaviors during normal their practical application as an such as aircraft and factories. enabling technology for autonomous

108 P ROGRESS IN SPACE TECHNOLOGIES S PACE SCIENCE ENTERPRISE

and abnormal operations. The RA is the research, Ames can effectively capable of responding autonomously focus the research efforts on practi- to system and payload faults and cal problems at the cutting edge of malfunctions, establishing contact technology. with ground operations personnel Point of Contact: K. Swanson when necessary, and replanning (650) 604-6016 portions of the mission onboard to [email protected] accommodate unanticipated changes in spacecraft performance or objectives. The DS1 mission will be the first ever to fly an onboard autonomous agent flight system. Program management objectives are (1) managing Ames and JPL team personnel; (2) defining development schedules, descope options, and contingency plans when necessary; (3) preparing and presenting status reviews and briefings to program management, Center management, and review boards; (4) making budget and workforce projections; and (5) acquiring the necessary resources to allow the team to accomplish its goals. Technical objectives include flight/ground interface design, RA design over- sight, and the performance of engineering duties related to autonomous systems such as defining command and telemetry system requirements, fault protection system policies, and FSW validation policies. Successful development of an RA FSW architecture for NMP DS1 will identify new avenues of research which will guide the growth and development of the next generation of “thinking” spacecraft. The RA architecture will be expanded to be used in a wide variety of manned and unmanned vehicles. By carefully selecting applications projects to accompany

P ROGRESS IN SPACE TECHNOLOGIES 109 Human Exploration and Development of Space Enterprise

110 H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

O v e r v i e w acquired by a two-pronged approach: (1) Research is conducted NASA’s Human Exploration and on the ground and in space over a Development of Space (HEDS) range of gravitational levels and with enterprise brings the frontier of space a variety of biological specimens; fully within the sphere of human and (2) specialized equipment and activity. Ames supports the HEDS advanced technologies are devel- enterprise by conducting research, oped to support life-sciences managing spaceflight projects, and research on the ground and in space. developing advanced technologies. The knowledge thus acquired is then An objective of these efforts is to integrated and disseminated by using seek knowledge of physicochemical information technology. and biological phenomena that can In this report, new life-sciences be fully explored only at very low research findings are presented; for gravity levels. This objective example, new biochemical assays of embraces the quest for knowledge bone collagen degradation, which of the role and influence of gravity in are useful tools for monitoring bone living systems—one of the elements mineral loss (a major biomedical of NASA’s astrobiology activities. problem of long-duration human A second objective is to develop spaceflight). Other research shows technologies for advancing human that both cerebral blood flow exploration of space and achieving velocity and cerebral oxygenation routine space travel. A complemen- decrease prior to fainting. This tary objective is to apply knowledge finding improves our understanding generated in pursuit of these objec- of the typical orthostatic intolerance tives, where feasible, to enrich life and fainting observed in many on Earth. During FY96, numerous astronauts following spaceflight. research and technology efforts that Additional work has focused on addressed the following goals of understanding the process of dual the HEDS enterprise were adaptation (or separate adaptations accomplished: to two mutually conflicting sensory inputs) as it applies to the altered • Increase knowledge of nature’s gravity environment. These studies processes using the space should provide greater insight into environment. the processing of altered gravita- • Advance human exploration of tional inputs directly relevant to an the solar system. astronaut’s ability to function well • Achieve routine space travel. in space. • Enrich life on Earth through Technological advances educational, commercial, and described in this report have numer- technological opportunities in ous applications in the medical and space. biomedical fields. The Virtual Environment Surgery Workbench, in New knowledge and an increase combination with software originally in the understanding of nature’s developed for an Ames spaceflight processes related to the influence experiment with rodents, has of gravity on living systems are

111 attracted much interest from recon- the patient in the characteristic particulates, odors, and the kinds of structive surgeons, and this tool is supine position but with loads added chemicals and biological specimens expected to decrease the training to the spinal column simulating required by life scientists. time of a skilled craniofacial those that occur naturally in the To help astronauts achieve reconstructive surgeon from 20 to upright posture. Such imaging maximum productivity during the 10␣ years. In addition, this technology capability will provide a greater particularly crucial first days of may soon offer doctors in the range of diagnostic data for doctors flight, researchers at Ames have emergency room real-time, high- who treat the millions of people who been working on ways to reduce fidelity, three-dimensional informa- suffer back pain. the space adaptation syndrome. tion so that accurate diagnoses and Another recent Ames project Autogenic-Feedback Training (AFT) potential reconstructive alternatives involving telemedicine, Spacebridge seems to be effective in controlling can be quickly determined. to Russia, linked three U.S. hospitals motion sickness under a variety of Neural net software develop- and a university with two medical conditions, including spaceflight. ment has resulted in another medical centers in Moscow via the Internet. The AFT exercise technique can also technology aimed at increasing the Ames is responsible for developing be used to control blood pressure capability of neurosurgeons. The the technical architecture as well as and thus ameliorate postflight software enables a robotic probe to providing direction in setting up the orthostatic intolerance. “learn” a patient’s brain characteris- Internet connections and the motion Lower-body negative pressure tics, making it easier for a surgeon to video consultation and video equipment specifically developed as locate the exact position of a tumor teleconferencing features. These a potential countermeasure for the after surgery is under way and the capabilities have already enabled debilitating effects of long-term normal swelling of brain tissue telemedicine consultations among human spaceflight has been modi- complicates the process. all test users, and plans are under fied to provide a variety of loading In the ongoing effort to develop way to utilize the system as an levels on the lower body. In combi- methods to monitor vital blood educational tool for hospitals. nation with a treadmill, the equip- constituents, a prototype system that As part of the HEDS goal to ment has applications both as a has application to astronaut health, explore the solar system, Ames has countermeasure to the atrophy of space life sciences, and Earth-based actively pursued life-support meth- the musculoskeletal system during medicine has been created. Concen- odologies relating to atmosphere spaceflight and as a rehabilitative trations of ions in flowing blood regeneration, water purification, tool for treating patients suffering plasma can now be measured recycling from waste materials, and spinal trauma on the Earth. by a computer-controlled data- food production. The work has given The use of a device that com- acquisition system known as the birth to new concepts of reducing bines resistive exercise with aerobic Blood Flow Ion Analyzer. Liver- spacecraft power and weight training is described. Presently, function support systems are direct requirements. cardiovascular exercise is empha- beneficiaries of this technology, as Research in the unique environ- sized during Space Shuttle missions; there is a specific need to continu- ment of space requires specialized however, research with the “SX-1 ously monitor and control ion equipment to operate within Variable Resistance Exercise Device” concentrations of processed blood microgravity and assure that the suggests that astronauts may be able plasma. research conducted does not pose a to maintain muscle size and strength A spinal compression harness health or safety risk to the human while also maintaining bone density designed as a potential aid to crews. One such piece of equipment during spaceflight. astronauts in combating back pain developed during the past year is the It is vitally important that the during spaceflight is also of interest standard interface glovebox, which results of HEDS research be quickly to orthopedic therapists. The harness is now flying aboard the Mir station. disseminated to the public, that is, allows doctors to perform magnetic This device was designed to provide the commercial sector and the resonance imaging while positioning an enclosed workspace that contains

112 H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

educational and scientific communities. To this end, life-sciences spaceflight data are being published in the scientific and popular literature and archived in the National Space Science Data Center at the Goddard Space Center. Ames is also actively engaging teachers and students to promote science education of our nation’s youth.

113 FA ASTRONAUTSTRONAUT HHEALTHEALTH/S/SCIENCECIENCE depressed formation, but no histo- higher than in six-month-old mature logic or biochemical measurements animals (see the figure). This age support this idea. difference reflects growth rates that Biochemical Markers of To evaluate bone resorption, average 2-3 grams per day in Bone Metabolism in a Rat an assay that measures deoxypyri- juveniles and are stable and essen- Spaceflight Model dinoline (Dpd), a product of the tially zero in mature animals. breakdown of collagen crosslinks in Exposure to the spaceflight model Meena Navidi, Jeanne Wren, bone was used. This assay is cur- for 14 days reduced Dpd excretion, Sara Arnaud rently regarded as one of the most whereas it remained unchanged in specific and sensitive markers of the control juveniles. In contrast, Newer biochemical assays of bone resorption. The 24-hour mature rats showed increases in Dpd bone collagen degradation products excretion of Dpd in two-month-old excretion after 14 days exposure to in urine are useful tools for monitor- juveniles was more than seven times unloading, as shown in the figure. ing bone loss (a major concern of spaceflight) and the effects of countermeasures to prevent bone loss in human adults. The results 840 reflect the collective metabolic Control activities of bone resorption in the 720 Space flight model entire skeleton, a process that is activated by exposure to a head- 600 down tilt, bed-rest spaceflight

model. These techniques have yet to 480 be applied to small-animal models of weightlessness. Through histo- 360 logic methods, the decrease in new * bone formation in the rat tibia during

Dpd nM/mM creatinine 240 spaceflight is well documented. * Recently, increases in osteoclast 120 number and resorption were observed in highly localized areas 0 in the proximal tibia. Ground-based Mature rats Juvenile rats models of juveniles of the same species show morphologic changes Fig. 1. The 24-hour excretion of deoxypyridinoline in the urine of juvenile consistent with reduced bone and mature rats prior to and 14 days after exposure to a spaceflight model in formation in unloaded hind limbs which the hind limbs were unloaded. Note the higher excretions (p < 0.05) with no evidence for increased in the young animals than in the mature animals, and the opposite responses resorption. The mature rat, exposed to the model at each age. to the same ground-based model with unloaded hind limbs for 28␣ days, reveals less bone mineral content in the femur, compared with ambulatory controls. This apparent bone loss is thought to be caused by increased resorption as well as

114 A STRONAUT HEALTH / Science H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

These results illustrate the Cerebrovascular within the middle cerebral artery marked, age-dependent differences was measured with transcranial in the response of the skeleton to a Responses Prior to Doppler sonography. Cerebral tissue weightless environment. Results in Fainting oxygenation was monitored using the mature animals, who at six Kana Kuriyama, Toshiaki Ueno, near-infrared spectroscopy over the months of age have acquired 96% Richard E. Ballard, forehead. of the bone they will have in their Donald E. Watenpaugh, During the initial stages of lifetimes, are similar to the increases Suzanne M. Fortney, LBNP stress, when blood pressure observed in human adults. There is Alan R. Hargens decreases and heart rate is elevated, an increase in bone resorption after these cardiac responses are caused unloading the skeleton, a situation Reduced orthostatic tolerance, by blood pooling in the legs. But favorable to bone loss unless commonly observed after space- as LBNP continues, cardiac insuffi- accompanied by an increase in bone flight, occasionally causes fainting ciency occurs prior to fainting. This formation. Alkaline phosphatase, a during standing. Prefainting condi- study focused on the 2-minute circulating marker of bone forma- tions are usually manifested by period prior to the fainting endpoint tion, was unchanged in this study. symptoms such as a sudden drop of when LBNP was stopped. In a The opposite result, suppression of heart rate or blood pressure that is typical subject, blood pressure high resorption rates in juveniles, followed by loss of consciousness if continued to decrease gradually as could be related to depressed growth standing is continued. Although the fainting was approached (see the hormone or a growth factor during cerebrovascular system may play an figure). Heart rate decreased rapidly exposure to the model. While it is important role in postflight fainting, in the final 30 seconds, signifying clear that the adaptation of the there have been few reports con- cardiovascular insufficiency just skeleton to microgravity requires cerning cerebral hemodynamics prior to fainting. site-specific changes in the rates of prior to fainting. This study was The new finding of this study formation and resorption in weight- therefore undertaken to investigate is that both cerebral blood-flow bearing bones (to modify bone cerebrovascular responses by velocity and cerebral tissue oxygen- structure for new loads), there also measuring cerebral blood-flow ation decrease prior to fainting. The appears to be a systemic response velocity and cerebral tissue oxygen- decrease of cerebral blood-flow reflected in bone marker assays ation prior to fainting, using lower- velocity can be explained as a that quantifies overall skeletal body negative pressure (LBNP) as an decrease of cerebral blood flow or metabolism. orthostatic stress. a dilatation of the middle cerebral Seven healthy male volunteers artery. The decrease of cerebral Point of Contact: M. Navidi were exposed to supine LBNP in tissue oxygenation can be explained (650) 604-5755 steps of 10 millimeters Mercury as a decrease of cerebral blood flow [email protected] every 3 minutes until prefainting or less likely, a decrease of cerebral symptoms were detected. Blood tissue metabolism. Therefore, it is pressure and heart rate were mea- probable that cerebral blood flow sured with an automatic finger-cuff decreases just prior to fainting. device. Cerebral blood-flow velocity

A STRONAUT HEALTH / Science 115 In conclusion, during LBNP- 110 induced fainting, cardiac insuffi- 100 ciency primarily occurs, resulting 90 in the failure of cerebrovascular circulation. This study improves the 80 (mmHg) understanding of postflight fainting 70 Blood pressure in astronauts and may aid in the 60 development of preventive methods.

Point of Contact: A. Hargens 90 (650) 604-5746 80 [email protected] 70 60 Heart rate (beats/min) 50 40 Chronic Exposure to Hyper-G Suppresses Otolith-Spinal Reflex in 40 the Rat

25 Nancy G. Daunton, Merylee Corcoran, Robert A. Fox, (cm/sec)

CBF velocity 20 Li-Chun Wu

As part of an ongoing effort to understand the neural mechanisms 0 underlying adaptation to altered gravity, behaviors reflecting the Ð.1 function of gravity receptors (otolith Ð.2 organs) in the inner ear (for example,

(volts) air-righting reflex, orientation) of the

Oxygenation Ð.3 rat have been studied following Ð.4 chronic hyper-gravity (hyper-G) Ð120 Ð100 Ð80 Ð60 Ð40 Ð20 0 20 40 60 exposure and found to be consider- End ably altered. In addition to the point behavioral data, morphological Time (sec) studies conducted by Ross in Fig. 1. Blood pressure, heart rate, cerebral blood-flow (CBF) velocity, and conjunction with the behavioral cerebral oxygenation with emphasis on the final 2 minutes prior to lower- studies have shown that there is a body negative pressure (LBNP)-induced fainting. Baseline values of each reduction in numbers of synapses on measurement (n) represent supine data obtained just before starting otolithic hair cells in the utricular LBNP protocol. maculae of animals exposed to the same chronic hyper-G conditions. These behavioral and morphological findings suggest that the sensitivity or gain in the otolithic system may be

116 A STRONAUT HEALTH / Science H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

decreased following chronic Analysis of the data showed that The results of this study suggest hyper-G exposure. in animals exposed to hyper-G, the that chronic exposure to increased One way to evaluate the gain or majority of responses (61%) to the gravitational conditions leads to a sensitivity in the otolithic system is free-fall stimuli were of very low decrease in the sensitivity or gain of to use the “free-fall” response, which amplitude (suggesting low sensitivity the gravity-sensing (otolith organ) is an otolith-spinal reflex elicited by or gain), while normal, control portion of the vestibular system. a sudden brief vertical-linear accel- animals had very few (13%) low- Furthermore, a greater degree of eration or drop. Using electromyo- amplitude responses (see the figure). suppression is produced by expo- graphic (EMG) techniques, this Furthermore, a significantly higher sures to higher G levels. This response has been demonstrated in a percentage of responses were low decreased sensitivity may underlie number of muscles in animals and amplitude in animals exposed to the deficits in otolith-mediated humans. The earliest component of 2.8␣ G than in those exposed to behaviors seen following chronic this response is dependent on intact 2.0␣ G. This suggests greater loss of hyper-G exposure and may be otolith organs and does not habitu- sensitivity or gain with centrifugation related to the reduced numbers of ate over trials. at higher G levels. In all cases synapses found in otolith organs The otolith-spinal reflex animals exposed only to the rota- under the same conditions. The response to sudden free-fall was tional component of centrifugation critical next question is whether the used to monitor sensitivity or gain had response amplitudes similar free-fall response will be increased in the otolithic system following to those seen in normal control following chronic exposure to chronic exposures to hyper-G. The animals that were not exposed to microgravity. If that is the case, investigators hypothesized that the centrifugation. amplitude of the early EMG response would be lower in animals exposed to hyper-G than in animals experi- Free-Fall Response encing only the normal 1-G Gastrocnemius muscle environment. A free-fall apparatus was Hyper-G Control developed that allows the animal, (n = 4) (n = 4) in a prone position, to be dropped suddenly over a 40-centimeter distance and then gently stopped by pairs of “soft springs.” This device provides a sudden, vertical-linear- Drop Drop accelerative, free-fall stimulus to the animal being tested. Animals were 2 mv instrumented with EMG electrodes in the gastrocnemius muscle of the hindlimb. The EMG response, along with acceleration of the animal, was 250 ms recorded during 10 drops for each Average rectified EMG - R + 4 hrs animal. The animals were tested within 3.5 to 9 hours following Fig. 1. Average rectified electromyographic (EMG) response from four chronic (7 to 14 days) exposures to animals exposed to 2 G for 7 to 12 days and from four control animals, hyper-G produced by centrifugation showing reduced amplitude of average response in hyper-G animals as on the Ames Research Center compared with control animals. 24␣ Foot-Diameter Centrifuge.

A STRONAUT HEALTH / Science 117 important evidence will be obtained The first investigation, One, subjects actively turned the on how the otolith organ system conducted by R. B. Post (University head during alternating exposure to is modified to subserve optimal of California, Davis) and R. B. Welch (a) the visual-vestibular rearrange- vestibulo-spinal function (orienta- (NASA Ames Research Center), ment (target/head gain = 0.5), and tion, postural control, locomotion) in measured perceived movement of (b) the normal situation (target/head altered gravitational environments. a stationary visual stimulus during gain = 0.0). These conditions head movements, known as “appar- produced both adaptation and Point of Contact: N. Daunton ent concomitant motion” (ACM). dual adaptation of the VOR, but no (650) 604-4818 ACM was measured both before evidence of adaptive generalization [email protected] and after exposure periods in which when tested with a target/head gain subjects performed voluntary head of 1.0. oscillations while viewing a spot that Experiment Two, in which moved in conjunction with the head. exposure to the 0.5 gain entailed “Dual Adaptation” to During these intervals, subjects externally controlled (that is, passive) Space-Related Sensory looked at the spot as it moved whole body rotation, resulted in alternately in the same direction as VOR adaptation, but no dual Rearrangements the head was moving during either adaptation. As in Experiment One, Robert B. Welch 0.25 or 2.0 hertz head oscillations, no evidence of adaptive generaliza- and then in the opposite direction tion was found. It was concluded A series of studies is examining as the head at the other frequency. that it was the absence of a salient the process of “dual adaptation” in a After a period of exposure, the visual discriminative cue in the passive variety of atypical sensory environ- stimulus came to be perceived as rotation experiment that prevented ments representative of those likely stationary only if it was caused to dual adaptation from occurring. to be experienced by astronauts. The move in the same direction as that In the third investigation, term “dual adaptation” refers to the viewed during adaptation at the conducted by R. B. Welch and acquisition of separate, relatively same frequency of head motion. N. Daunton (NASA Ames Research independent adaptations to two (and Thus, these results confirmed the Center), R. Fox (San Jose State perhaps more) mutually conflicting presence of dual adaptation of ACM University), and M. Corcoran and sensory environments resulting from in which the stimuli used to identify L. Wu (NASA Ames Research repeated alternation between the prevailing sensory environment Center), albino rats underwent four, exposure and adaptation to one of were those associated with head- 7-day periods of continuous 2-G the sensory environments and movement frequency. exposure, by means of centrifuga- exposure and adaptation to the other In the second investigation, tion, which alternated with four, environment. Evidence of dual conducted by R. B. Welch 7-day periods of normal gravity adaptation is seen in a progressive (NASA Ames Research Center), (1␣ G). Before and after each 7-day decline in (1) the perceptual and/or B. Bridgeman and J. A. Williams period, subjects were measured on behavioral interference that occurs (University of California, Santa (a) their righting reflex when at the initial transition between the Cruz), and R. Semmler (University dropped suddenly from an initially two sensory conditions, (2) the of Clausthal, Germany), two experi- supine position into a vat of water amount of exposure necessary to ments examined the possibility that 40 centimeters below (“air righting”), produce asymptotic adaptation, the human vestibulo-ocular reflex and (b) swimming behavior after and/or (3) the amount of adaptation (VOR) is subject to dual adaptation, striking the water. Latency to the acquired after a given amount of as well as “adaptive generalization,” occurrence of air-righting was found exposure. During FY96, three which is the ability to adapt more to be subject to a form of dual investigations of dual adaptation readily to a novel sensory rearrange- adaptation. Specifically, animals were completed. ment as a result of prior dual- that were repeatedly tested showed adaptation training. In Experiment a significant improvement in mean

118 A STRONAUT HEALTH / Science H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

speed of air righting (+47%; and permits several individuals to “soft spot”). The images of the skull p = 0.008), while control animals see the visualization projected above clearly show the extent of fusion of who received 2-G exposure, but the table top in three dimensions. the bones. Without surgical interven- were only tested on righting (and Special glasses are required (see tion, the right side of the head would swimming) after the last of the 7-day the figure). The images are greatly not grow properly, the head and face exposure periods, showed only a enlarged so that a novice can see would be deformed, and the brain marginally significant (p = 0.12) details readily. The images can then would be compromised. Because of 25% improvement in mean be reduced in size to attain a more the high fidelity of the viewed air-righting speed. true-to-life size for further practice. images, surgeons have declared the This workbench will be used as software ready to use as a diagnostic Point of Contact: R. Welch interactive, VE tools are developed tool. The goal is to have even more (650) 604-5749 for training and planning purposes. complex reconstructions completed [email protected] Also, displayed images can be sent within 15 minutes, or less, making it to remote sites over a network. The possible for doctors in emergency goal is to have interactive displays so rooms to have a patient scanned and that researchers and surgeons at see the trauma in 3-D within min- T TECHNOLOGYECHNOLOGY A APPLICATIONSPPLICATIONS TO TO HUMAN ␣␣HHEALTHUMAN HEALTH remote sites can see identical three- utes. In addition, work is beginning dimensional (3-D) images and that will make it possible to port the interact with them. software to less expensive worksta- Virtual Environment In the Biocomputation Center, tions, promoting wider availability of Surgery Workbench unique software has been developed the technology. that permits detailed, 3-D recon- A necessary part of the software Muriel D. Ross struction of the face and skull of development is the ability to cut out, patients from computerized tomog- to remove, and to insert pieces of The research and development raphy (CT) scans. The Visible bone elsewhere, then to computa- of a virtual environment (VE) surgery Human Dataset provided by the tionally restore the soft tissues so that workbench was undertaken by the National Institutes of Health was the new face can be molded to the Biocomputation Center in FY96. This used to reconstruct the face and new skull for viewing prior to workbench will be used for training skull of a 57-year-old female. In the surgery. Software has been devel- reconstructive surgeons and for reconstruction of the face, even tiny oped to do this using a model grid patient-specific planning of complex wrinkles around the mouth can be system. The software will be incor- craniofacial and other reconstructive seen, and deeper wrinkles and the porated for use with an actual skull surgeries. The virtual environment texture of the skin are realistic. as the next step in software develop- technology will be useful to the Because of the level of detail ment. The software will be generally Human Exploration and Develop- possible, a laser scan to record the applicable, for example, in recon- ment of Space (HEDS) Enterprise for face prior to surgery is no longer structive surgery utilizing skin to training astronauts for long-term needed. The images are rendered recreate a breast in a mastectomy missions in space. It will provide VE with high fidelity. patient. simulation capability during space- The face and skull of an infant The value of the training aspects flight to help astronauts respond patient was generated from format- of the technology should not be appropriately to unanticipated ted CT scans in about 20 minutes underestimated. It takes as many as emergencies. using the newly developed software 20 years to train a highly skilled The Immersive WorkBench and a Silicon Graphics Onyx RE2 craniofacial reconstructive surgeon. (Fakespace, Mountain View, CA), workstation. The infant had prema- If training in a simulator reduces this is used for displays (shown in the ture closure of a skull suture on the amount by half, 10 productive years figure (see Color Plate 20 in the right and of part of the anterior will be added to a surgeon’s profes- Appendix)). This workbench is large fontanelle (commonly known as the sional life. Furthermore, use of

T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH 119 simulator technology greatly reduces cause or exacerbate similar symp- neural activity. Consequently, ICP is the cost of training. It is cheaper to toms during spaceflight. In addition, a critical parameter for understand- practice on a computer than to recent clinical reports suggest that ing physiologic adaptation to participate in surgery on a patient elevated ICP impairs regulation of microgravity. However, the magni- and learn in this prolonged way. blood flow in the brain and normal tude and time course of altered ICP Also, new approaches to surgery can be quickly incorporated into a Ð.03 50 simulation to increase capability in PPLL new surgical techniques. Ð.04 ICP The VE technologies that are 40 being developed will reduce medi- Ð.05 cal costs, shorten the time necessary Ð.06 to train surgeons, and permit better 30 preplanning of surgery. They also Ð.07 will improve the quality of life for 20

Ð.08 ICP (mmHg) the patient by producing a better

outcome when surgery is first carried PPLL output (voltage) Ð.09 out. As these beneficial VE technolo- 10 Ð.11 gies are transferred to the public, NASA also benefits from these Ð.12 0 applications that are useful to the 0 2 4 6 8 10 12 14 16 18 20 HEDS Enterprise and to long-term Time (sec) spaceflight.

Point of Contact: M. Ross (650) 604-4804 .006 10 [email protected] PPLL

.005 ICP 8

.004 Noninvasive Estimation 6 of Pulsatile Intracranial .003 Pressure Using Ultrasound 4

.002 ICP (mmHg/Hz) Toshiaki Ueno, Richard E. Ballard, PPLL output (voltage/Hz) John H. Cantrell, William T. Yost, 2 Alan R. Hargens .001

Exposure to microgravity causes 0 0 a blood shift toward the head that 0 1 2 345678910 may elevate intracranial pressure Frequency (Hz) (ICP). As widely observed in patients with brain tumors or hemorrhage, Fig. 1. Results of cadavera study. Typical waveforms in the pulse phase elevation of ICP may cause head- locked loop (PPLL) output and ICP are shown as a solid line and a dash line, ache, nausea, or vomiting. These respectively. ICP pulsations were generated manually by infusing saline into conditions strongly suggest that the ventricle at a rate of 1 cycle/second (1 hertz). The units of the PPLL elevated ICP in microgravity may output are voltages. The results of frequency analysis are superimposed.

120 T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

10 degree head-down tilt positions. .004 ICP was not measured directly. In .003 n = 6 both of the experiments, an ultrasound transducer was taped securely .002 to the lateral head above the .001 right ear. 0 In the cadaver study, frequency analysis (fast Fourier transformation) Ð.001 revealed that cranial pulsations were Ð.002 clearly associated with ICP pulsa-

PPLL output (voltage) Ð.003 tions (see the first figure). In the tilt study, the magnitudes of cranial Ð.004 y = Ð6E Ð 05x + 0.0012 pulsations were linearly correlated to R2 = 0.749 Ð.005 tilt angles as shown in the second Ð.006 figure. Ð20 Ð10 0 10 20 30 40 50 60 70 The ultrasound device has Tilt angle (deg) sufficient sensitivity to detect cranial pulsation associated with cardiac Fig. 2. Results of tilt study (n = 6). Amplitudes of pulsatile changes in the cycles. As previously reported, the PPLL output are shown against the tilt angles. A linear regression line is amplitude of ICP pulsations is superimposed. closely related to intracranial compliance. In other words, when intracranial fluid volume and are still unknown, primarily because transducer placed on the head. The pressure increase, arterial pulsation of the invasiveness of currently ultrasonic wave passes through the produces a higher amplitude ICP available techniques. cranial cavity, reflects off the inner pulsation. Increased amplitude of A new ultrasound device to surface of the opposite side of the ICP pulsations will be manifested by measure skull movements that occur skull, and is received by the same larger fluctuations in distance across with altered ICP has been developed transducer. the skull. Accordingly, by analyzing and refined. The principle of this In the first experiment, changes the magnitude of cranial pulsations, device is based upon pulse phase in cranial distance in three cadavera absolute estimates of ICP during locked loop (PPLL), which enables (ages 85–90) were measured with spaceflight are possible. the detection of changes in distance the ultrasound device, while pulsa- on the order of micrometers between tile changes in ICP were generated Point of Contact: A. Hargens an ultrasound transducer on one side by infusing saline into the lateral (650) 604-5746 of the skull and the opposite inner ventricle. To correlate the non- [email protected] surface of the cranium. Although the invasive measurement with ICP skull is often assumed to be a rigid directly, a fiber-optic, transducer- container with constant volume, tipped catheter was inserted into the many researchers have demonstrated intracranial space. In the second that cranial bones move in associa- experiment, changes in cranial tion with changes in ICP. In the distance in six healthy volunteers typical operation, the instrument (ages 18–31) were measured while transmits a 500 kilohertz ultrasonic they were placed in 60 degree, tone burst through the cranium via a 30␣ degree head-up tilt, supine, and

T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH 121 MRI-Compatible Spinal connected to shoulder pads, and and alleviate back pain in astronauts alternatively to a head cap, by nylon during spaceflight, when spinal Compression Harness webbing and elastic cords. Pulling length increases between 4 to Richard E. Ballard, the webbing through plastic buckles 7␣ centimeters. Donald E. Watenpaugh, allows adjustment of cord tension, In a recent pilot study, four Iwane Mitsui, Klaus P. Fechner, and thus compression level. The healthy male subjects (age: 33–52; Douglas S. Schwandt, Alan R. Hargens amount of compression is measured weight: 72–113 kilograms) were by nonmetallic force sensors that are fitted with the spinal compression Sixty to eighty percent of the currently being manufactured by a harness and placed in supine posture population of the United States commercial partner. Alternative within an MRI scanner. Each sub- experiences back pain during their features of the device include a ject’s spine was imaged without lives. While noninvasive imaging helmet-like headgear with adjustable compression (control condition) and systems such as magnetic resonance elastic straps to provide neck again at 25% and 50% body weight imaging (MRI) and computed compression, a saddle to distribute compression (the lumbar spine bears tomography scanners have been compression to the seat, and other about 50% body weight in upright used as diagnostic tools for studying attachments that allow static and posture). Three of the subjects back pain and orthopaedic injury, dynamic compression of specific underwent an additional compres- these imaging devices require body segments or joints. A space- sion level of 75% body weight (see patients to lie down, thus eliminating related benefit of the device includes the second figure). Longitudinal any effect of axial loading on the the potential to compress the spine distance between T7/T8 (thoracic body that occurs in upright posture. As a result, these imaging systems often provide diagnostic data of limited use, particularly to disorders related to loading and unloading of 10% the spine. The MRI-Compatible Spinal Compression Harness (a patent 50% recently filed by NASA Ames) is designed to produce gravity-like axial compressive loads on the body, thus increasing the effectiveness of existing diagnostic imaging systems for detecting spinal disorders. In 50% 50% 50% addition, the spinal compression device will help researchers study 100%

the physiology and biomechanics of Upright Supine compression in MRI intervertebral discs and causative mechanisms of back pain in patients Fig. 1. Percentage of body weight locally supported during upright posture on Earth and astronauts in space. (left) and supine compression in MRI (right). In upright posture, a gradient of The spinal compression appara- weight-bearing exists from the head to the feet, whereas the harness for MRI tus is lightweight, compact, and compresses tissues uniformly between the sites of compression. Thus, loads inexpensive, and fits into existing are adjusted to the specific tissue to be scanned under load (for example, the diagnostic equipment without costly lumbar spine typically experiences 50% body weight in upright posture). modifications (see first figure). In its present configuration, the device consists of a nonmetallic footplate

122 T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

level) and L5/S1 (lumbar/sacral level) discs decreased by 3.2 ± 0.8 millimeters (mean ± SD) with 25% body weight compression, 5.6 ± 1.1 millimeters with 50% body weight compression, and 6.8 ± 1.2 millimeters with 75% body weight compression. The distance reduction was attributed to decreased disc thickness and increased spinal curvature. While further development and validation of this technology are necessary, these results indicate that the spinal compression harness is capable of loading the spine effectively during supine MRI, and thus may be a valuable tool for studying effects of gravity-like loads on the spine. Previously this capability has not been available to researchers or (a) clinicians.

Point of Contact: A. Hargens (650) 604-5746 [email protected]

Near-Infrared Spectroscopy to Monitor Forearm Muscle Oxygenation Gita Murthy, Alan R. Hargens

Muscle pain can be caused by repeated and constant exertion of a specific muscle. Such exertion may increase muscle pressure, reduce (b) blood flow and muscle oxygenation, Fig. 2. Side view (a) and front view (b) of a spine during MRI with graded and cause muscle fatigue and pain. compression. Note the increase in curvature with increased load. This Low levels of prolonged muscle particular subject had a slightly bulging disc on the posterior side of L3-L4 contraction of the forearm muscles (third visible disc from the bottom) which was accentuated by compression. are common in many work settings BW = body weight. and may cause fatigue. Crew operations in the Life Sciences

T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH 123 Glovebox on the Space Station is placed over the forearm muscle and maximum voluntary contraction. At one such work environment. The gently secured with an ace wrap. the end of the minute, the load was purpose of this study was to deter- Subjects were asked to contract their removed and a 3-minute recovery mine whether forearm muscle forearm muscle maximally three period followed. At the end of the oxygenation decreases significantly times. After 1 minute of data collec- protocol, with the spectroscopy at low levels of contraction. Nine tion during relaxed posture, subjects probe still in place, subjects were male and female subjects partici- contracted their forearm muscle required to exercise their forearms pated in the study. Each subject was once again for 1 minute, during four to exhaustion such that very little seated as shown in the first figure. different load applications (randomly muscle oxygenation was recorded. Muscle oxygenation was ordered). Loads were imposed by This procedure is necessary to obtain measured noninvasively using a weights that were placed on the a functional zero level for each near-infrared spectroscopy tech- knuckles and allowed the subjects subject. The data were normalized nique. The spectroscopy probe was to work at 5, 10, 15, and 50% of to a relative scale between the physiologic minimum (0%) established during the exhaustive exercise and the spectrophotometer output during relaxation (100%). After 35 and 40 seconds of contraction, muscle oxygenation leveled off at below baseline levels and remained at that level throughout the 1-minute contraction period. Muscle oxygenation decreased from 100% during rest to 89 ± 4% (SE), 81 ± 8%, 78 ± 8%, and 47 ± 8% at 5, 10, 15, and 50% maximal forearm contraction, respectively (see the second figure). Muscle oxygenation decreased significantly at 10, 15, and 50% of maximal contraction compared to resting values. This study shows a significant reduction in muscle oxygenation even at levels as low as 10% maximal contraction. Muscle deoxygen- ation during muscle contraction may play an important role in the development of muscle fatigue and pain associated with repetitive tasks, especially in confined environments such as in a glovebox. There are no Fig. 1. Subject posture during the study. The inset shows the spectroscopy simple, easy to use instruments that probe that measures muscle oxygenation. can noninvasively measure muscle oxygenation in deep and superficial

124 T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

have membranes selective to only one ionic species. Since the porcine 100 liver cells decrease the plasma * calcium over time, requiring the * addition of Ca2+-enriched buffers, 80 the initial ion of interest is Ca2+. Monitoring the pH and temperature of the blood plasma is also desired 60 * and can be implemented with future prototypes. To measure concentrations with

40 ion-selective electrodes, a reference electrode that provides a concentration independent potential is needed. The potential of the ion- 20 selective electrode (indicator Normalized tissue oxygenation (% baseline) electrode) depends on the concentration of the ion for which it is 0 selective. The difference between 0 10 20 30 40 50 reference and indicator potential can Maximum voluntary contraction (%) then be related to the ion concentration; a process called calibration. Fig. 2. Muscle oxygenation decreases with increasing load on the forearm Ion-selective electrodes need to be muscle. calibrated before the first use and recalibrated after certain periods of time to minimize the amount of error working muscles. Thus, the spectros- BIONA 1—Blood Flow Ion generated by drift and changes in copy device may provide an impor- sensitivity (potential change per tant tool to study muscle fatigue and Analyzer decade change of concentration). pain and to improve the designs of John W. Hines, Christopher J. Somps The BIONA 1 system prototype workstations in space. Liver support systems will allows semiautomatic electrode Point of Contact: A. Hargens benefit from continuous monitoring calibration. Computer-controlled (650) 604-5746 and control of the ion concentrations solenoid valves are used to tempo- [email protected] of processed blood plasma. To rarily reroute blood plasma away measure the concentrations of ions from the sensor flow path to a in flowing blood plasma, a proto- bypass flow path during calibration. type, computer-controlled data One end of the sensor path, its inlet, acquisition system, the “Blood Flow is then connected to a syringe with a Ion Analyzer” (BIONA 1), has been calcium chloride buffer solution, and designed. BIONA 1 monitors plasma the other end, to a waste container. ion concentrations, displays them as This allows injection of buffer a function of time, and saves the solutions for calibration without data to a file for later analysis. The contaminating the blood plasma sensors are miniaturized, catheter- with buffer. After the buffers have type, ion-selective electrodes that been injected and calibration is finished, the inlet of the sensor path

T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH 125 is reconnected to the blood plasma digital signals to control (turn on/off) This technology development flow while its outlet is still routed to the solenoid valves. represented a diverse collaborative the waste container. This results in The solenoid valves require a effort between researchers and the removal of buffer solution from 12-volt DC power supply (at least technologists at the Center for the sensor path by the blood plasma 6␣ watt) that is provided by a wall Emerging Cardiovascular Technolo- flow. After a few seconds (flow-rate transformer. The amplifier circuit is gies (a National Science Foundation- dependent), all buffer has been powered by two AAA batteries for sponsored program managed from replaced by plasma. The sensor isolation purposes. To reduce the North Carolina State University), outlet is then switched back and the electromagnetic interference with and a team at the University of electrode tube is completely recon- the sensor signal, the box is copper North Carolina at Chapel Hill and nected to the blood plasma flow. clad to provide shielding. Shielding, other affiliates in the Research The prototype is currently limited to however, is only effective if the box Triangle, and at Case Western a plasma flow rate of approximately is grounded, which can be accom- Reserve University in Cleveland, 100 cubic centimeters per minute. plished by connecting the box with Ohio. A prototype Sensor Array for The electrode signal is amplified a ground wire to earth ground (for monitoring physiological ions in a by a high-input impedance amplifier example, from an outlet). A sche- hepatic bioreactor was demonstrated and acquired by a data acquisition matic of the BIONA 1 system is in a joint development activity with PCMCIA card and a laptop com- provided in the figure. the Department of Surgical Research puter. The same card also outputs and the Liver Support Group at the Cedars-Sinai Hospital in Los␣ Angeles, California.

Blood plasma supply Point of Contact: J. Hines (650) 604-5538 [email protected] Inlet Outlet

Bypass

Intelligent Controller for Neurosurgery Sensors Robert Mah

pCa pCa pCa pCa Ref In preparation for neurosurgery to remove tumors, magnetic resonance imaging (MRI) scans are usually taken to locate the tumor and its positional coordinates. However, during the surgical operation to access the tumor, the brain swells and the location of the Laptop PC with Waste tumor shifts. As a result, the neuro- PCMCIA DAQ-card surgeon must rely on experience to search for the tumor interface using Fig. 1. Blood Flow Ion Analyzer (BIONA 1) system diagram. surgical tools and tactile feedback. (Brain tumors typically have a

126 T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

different density than normal brain tissue). During this procedure, an artery can accidentally be severed by the surgical tool which can lead to death. A simple robot that can “learn” the physical characteristics of the brain may give surgeons more precise control of surgical instruments during delicate brain operations. The procedure utilizes a robotic smart probe that “learns” the brain’s characteristics by using neural net software. The probe, equipped with tiny sensors, enters the brain, gently locating the edges of tumors while preventing damage to critical arteries. Potentially, the neurocontrolled robot, making slow, very precise movements during an operation, will be able to “feel” brain structures better than any human surgeon. This research has contributed to the design of an intelligent robot that can improve the safety, accuracy, and efficiency of neurosurgery. This technology is expected to have direct spinoffs to the general field of surgery. In FY96, the NASA/Stanford Neurosurgical Computational Testbed was developed (see the figure). World-wide press coverage (major television stations, major newspapers, and radio stations) was received and an invention patent is pending.

Fig. 1. Robotic neurosurgical hardware testbed. Point of Contact: R. Mah (650) 604-6044 [email protected]

T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH 127 Center for Health (CDC), the CHAART staff worked to Planet Earth Enterprise to support intensively with CDC personnel in environmental research in the Applications of Aerospace Atlanta, Georgia, to develop col- Southwest. Related Technologies laborative projects. As a result of CHAART also provides RS/GIS (CHAART) these discussions, the CHAART staff support to Dr.␣ Uriel Kitron (Univer- organized and taught two workshops sity of Illinois, Champagne-Urbana), Byron Wood, Louisa Beck, Sheri on the uses of RS for public health who is funded by NIH to study the Dister, Brad Lobitz applications. These workshops were distribution of Lyme disease in the conducted at CDC Headquarters in Upper Midwest. The Center for Health Applica- Atlanta (May 6–7, 1996), and at tions of Aerospace Related Tech- Point of Contact: B. Wood CDC’s facility in Ft. Collins, Colo- nologies (CHAART) was initiated at (650) 604-4187 rado (May 27–30, 1996). Recom- the beginning of FY95 by NASA [email protected] mendations for future NASA/CDC Headquarters’ Life and Biomedical collaboration were generated at Sciences and Applications Division these events. As part of the NASA/ (Code UL), within the Office of Life National Institutes of Health (NIH) and Microgravity Sciences and MOU, the CHAART staff also spent Applications. The goal of CHAART is Telemedicine Spacebridge the year working with researchers to promote the application of remote to Russia funded through the NIH. These sensing (RS), geographic information researchers received supplemental Steve N. Kyramarios systems (GIS), and related technolo- funding through a joint NASA/NIH gies to issues of human health. Fiscal NASA’s newest telemedicine call, and used these funds to inte- year 1996 began with the First Cyril grate RS/GIS into their ongoing project, entitled Spacebridge to Ponnamperuma Symposium on Russia, is a collaborative effort research on disease. CHAART Remote Sensing and Vector-Borne between NASA and the Space directly assisted Dr. James Maguire Disease Monitoring and Control, (Brigham and Women’s Hospital at Biomedical Center for Research and held in Baltimore, Maryland, on Training in Moscow, and establishes Harvard Medical School), who is November 28–30, 1995. The a testbed to evaluate Internet studying leishmaniasis in Teresina, symposium, hosted by NASA and Brazil, and Dr. Rita Colwell (Univer- telemedicine in both operational the Third World Foundation (TWF), and educational settings. The project sity of Maryland), who is studying was attended by national health connects the Clinical Hospital of the cholera in the Bay of Bengal. representatives from Brazil, In other activities, CHAART also Ministry of the Interior in Moscow Cameroon, China, Indonesia, and the Moscow State Medical worked closely this year with TWF Malawi, Malaysia, Mexico, School sites with Baylor Medical personnel to identify 10␣ visiting Myanmar, Namibia, Nigeria, foreign scientists whose research or Center, Fairfax Hospital, Latter Day Rwanda, and Zimbabwe. The goal Saints Hospital, and Yale Medical jobs involve human diseases. These of the symposium was to develop School through the multicast back- scientists will spend two months at RS/GIS-based, health-related CHAART during FY97 learning how bone (MBONE). research proposals from Third World The goal of this project is to to integrate RS/GIS into their studies countries. The CHAART staff gave provide medical telecollaboration on human health. Two of CHAART’s tutorials on RS and GIS and led staff are on the Advisory Board of the and electronic patient record panel discussions to define country- production and review through the Pan American Center for Earth and specific issues. Internet. The program will help Environmental Studies. This center, As part of the new Memoran- established at the University of NASA develop a permanent dum of Understanding (MOU) telemedical system that provides Texas, El Paso, as a Minority Univer- between NASA and the Centers for medical support for its astronauts sity Research Center, was awarded a Disease Control and Prevention $6.5 million grant from the Mission and other personnel involved in the

128 T ECHNOLOGY APPLICATIONS TO HUMAN HEALTH H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

joint spaceflight program with deBakey, the world famous heart adsorption of carbon dioxide and Russia. In addition, the experience specialist. The educational program trace contaminants show significant gained from this effort will provide includes live multicast video and reduction in capacity of sorbents and insight into the potential of medical web-based medical imagery. the possibility of elution back into practice over the National Informa- Clinical consultations are prepared the cabin environment. New materi- tion Infrastructure and the Global at each site using a standard format als and operating procedures will Information Infrastructure. that includes motion video, data help mitigate this safety problem. This telemedicine testbed is transfer, still photography, and video New knowledge of adsorption between three clinical hospitals in teleconferencing capabilities. Cases processes has lead to a method of the United States (U.S.) (Fairfax are made available to the reviewing in␣ situ resource utilization of oxygen Hospital, Falls Church, Virginia; hospitals through a Web server. Each for Mars missions. Experimentally Latter Day Saints Hospital, Salt Lake site provides clinical coordination of validated, the process is likely to City, Utah; and Yale University, the cases on a rotating basis. fly on the Mars In Situ Propellant New Haven, Connecticut) and two Production/In Situ Resource Utiliza- Point of Contact: S. Kyramarios medical centers in Moscow (Clinical tion (ISPP/ISRU) Precursor experi- (650) 604-4950 Hospital of the Ministry of Interior ment in 2001. The data being [email protected] and the Space Biomedical Center for developed on materials have given Training and Research at Moscow insight into process modifications State University). UNIX-based that will reduce power and space

Silicon Graphics Inc. multimedia P ROGRESSPROGRESS IN IN I MPROVINGIMPROVING S PACESPACE requirements. This research program workstations are located at each site T␣␣TRAVELRAVEL supports contamination aspects of and are linked to the Internet. The flight experiments. workstations incorporate Internet tools including a graphical user Advanced Life Support/ Recovery of Resources from Waste interface (GUI) on the World Wide Human Exploration and Materials: Not currently recycled, Web, and the MBONE toolset for Development of Space human and food wastes are key video conferencing. It is estimated elements for advanced life-support that several hundred clinical consul- Enterprise Activities systems that approach self- tations will be conducted between Dick Lamparter, Mark Kliss sufficiency. Both Supercritical Water the clinical sites in the United States Oxidation (SCWO) and incineration and Russia. The Ames Research Center processors have been developed and In addition to engineering the (ARC) Advanced Life Support Branch are currently under evaluation. Key technical architecture, Ames carries out research and develop- issues being addressed include waste Research Center has contributed to ment of new technologies that will preparation and process feed and the project by providing technical advance the human exploration product stream cleanup, with a leadership and implementation in and development of space. These special focus on acid gases and Internet connectivity, motion video activities will reduce life cycle costs, other trace contaminants produced. consultation, and video teleconfer- improve operational performance, A prototype incinerator will soon be encing. These capabilities have promote self-sufficiency, and delivered to the Johnson Space enabled telemedicine consultations minimize expenditure of resources Center (JSC) for evaluation in an in a “grand round” format for unique for future space exploration. Signifi- extended manned chamber test. The case presentations. In addition, an cant opportunities for Earth applica- U.S. Navy has expressed interest in educational program organized by tion of the developed technologies SCWO technology for its potential to Baylor Medical Center in Houston, are available, including: reduce hazardous liquids to carbon Texas, is developing a series on dioxide and water while ships are recent advances in cardiology Atmosphere Regeneration: Data deployed at sea. under the direction of Dr. Michael on the influence of water on the

P ROGRESS IN IMPROVING SPACE TRAVEL 129 Food production: Activity in this Mir Hardware—Stepping and experiment development, and area is leveraged off prior research. pre/postflight processing have In collaboration with the National Stone to Station occurred three times annually and Science Foundation, a unit to Bonnie P. Dalton, James Connolly, have typically been initiated no produce fresh food at the South Pole Gary Jahns, Paul Savage earlier than 1.5 years prior to is being developed. The analysis of launch. As a result, hardware has dietary requirements, crop mix, and The Mir program has not only been developed very rapidly, with multicropping in growth chambers allowed the performance of biologi- applications to interim flights a has application to the Human cal experiments under long-term principal objective (until the Exploration and Development of microgravity exposure (for example, International Space Station is fully Space (HEDS) objective of providing 90 to 145 days), but also has pro- functional). self-sufficiency. Experience in vided a realistic view of experiences During the past 2␣ years, an dealing with crews in remote during the International Space insect habitat and a standard inter- environments is applicable to NASA. Station program in terms of opera- face glovebox (SIGB) have been Information generated from this tions and hardware preparations. developed for use on Mir. The insect program is being formatted as part In contrast to the Spacelab profiles, habitat was built with the assistance of the development of the JSC in which major flights occurred of Lockheed Martin Engineering and chambers. every 2␣ to 3 years, Mir flights and Sciences Company and other These activities form the basis the associated planning, hardware contract support. for an important technology transfer to native communities in Alaska where health hazards exist because of poor rural sanitation. Code STR has established cooperative agree- ments with the state, university, and local communities to apply the NASA-developed technology and systems analysis capability toward improving health, through diets and treatment of water and solid waste streams.

Point of Contact: M. Kliss (650) 604-6246 [email protected]

Fig. 1. Microgravity glovebox for Mir.

130 P ROGRESS IN IMPROVING SPACE TRAVEL H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

The SIGB was designed to vertebrates and invertebrates, it is Wireless Network provide a fully enclosed workspace anticipated that the ability to perfor the execution of in-flight science form long-term measurements on Experiment for Space procedures. The SIGB utilizes sliding Mir will greatly enhance the scien- Shuttle/Mir rails and latches adapted from the tific community’s knowledge of this Richard Alena Johnson Space Center’s standard subject. The Beetle Activity Module interface rack (SIR), allowing it to fly (BAM), the hardware housing the The Wireless Network Experi- in virtually any existing or future insect and the timing system, is an ment (WNE) was a risk-mitigation space platform. The work surface of adaptation of an existing item of experiment designed to demonstrate the unit is approximately 1 square Russian hardware with expanded the feasibility of using wireless foot and the work volume is capabilities. Housing 32 beetles, the networks aboard the International 2.3␣ cubic feet. Bounded by a BAM is self-contained, and includes Space Station. The customer was the fiberglass shell consisting of five both a treadmill and a timing system. Shuttle/Mir Science Program at the layers of epoxy resin, it is finished Food consists of a small quantity of Johnson Space Center (JSC), which is with white urethane for easy clean- dry oatmeal. Movement of a beetle under the Space Station Program. ing. Airflow within the unit is on the treadmill indicates the The WNE consisted of a set of three modeled after a laminar flow hood. insect’s activity during portions of computers that could communicate The air filtration system provides a its circadian rhythms. Data collected via the wireless radio network net negative pressure of 0.1 to from the flight experiment and from system, as shown in the figure. A 0.6␣ inch water with respect to ground-based centrifuge studies at network monitor program graphed ambient. All portions of the SIGB Ames Research Center will help network throughput in real time as airflow system maintain negative determine if the CTS exhibits the computers were moved through pressure with respect to ambient in adaptation during long-term expo- the habitable volume. This experi- all operational modes. The filtration sure to altered gravitational fields ment was successfully conducted system has been designed to provide and whether that exposure changes onboard both the Space Shuttle and full containment of spills for specific the sensitivity of the CTS to flight. Mir Space Station during the docked chemicals (used in biological fixative In summary, Ames’ participation space transport system-76/Mir 21 preparations), including Campbell’s in the Mir program resulted in the flight. Fixative, paraformaldehyde, and development of important hardware The current International Space Russian variant solution. Access for used for long-duration investigations Station data system baseline does operation is through attached and the methodology for rapidly not provide adequate support for gauntlet ports. The SIGB, ready for building and qualifying the hard- payloads and onboard computer mounting in the Space Transporta- ware. Additionally, Ames’ participa- systems. Adding additional cabled tion Service vehicle, is shown in tion has served as a vital educational network resources is prohibitive in the figure. stepping stone toward ensuring the terms of cost and weight. A wireless The insect habitat, known as success of activities onboard the network allows portable computing the Beetle Kit, was designed for a International Space Station. resources to be brought up to the NASA-5 increment experiment Space Station and installed with Point of Contact: P. Savage entitled “Effects of Gravity on Insect minimal effort and, at low-cost, (650) 604-5940 Circadian Rhythmicity” that will support a significantly augmented [email protected] study the Tenebrionid beetle. The data processing capability for hardware incorporates an automated payloads and crew. circadian timing system (CTS). Since previous spaceflights have shown a notable effect on the CTS of both

P ROGRESS IN IMPROVING SPACE TRAVEL 131 SNB WNS display module

WNS battery module

Display Battery Radio SIA module cable cable frequency wireless network 28 VDC and DM Bat chassis Power 10BaseT ground Power cable SCSI-II WNS PCMCIA Parallel server slot 1 module Peripheral RS-422 interfaces PDA (unused) RS-232 PCMCIA PCMCIA RF network cards slot 2 and antenna assembly - 3 places Video input

SVGA KB TB

Keyboard cable Trackball cable WNS WNS keyboard trackball module

Fig. 1. Schematic of the Wireless Network Experiment (WNE) system.

The WNE was conducted in Engine Diagnostic Filter The real-time analytic capability March 1996. Demonstration of the is unique in its ability to identify the next-generation (Web-based) data System principal eroding metal species system concept to NASA and JSC Tarang Patel under way in an engine during astronauts and engineering managers engine operation. Such health was made in May 1996. The post- The project objective was to monitoring activity can be used to flight testing and preliminary report develop posttest data analysis tools shut down an engine test prior to a were completed in August 1996. for potential deployment as real-time potential catastrophic failure. This and in-flight instruments for the next step could lead to a possible in-flight Point of Contact: R. Alena generation rocket engines for space capability, under research, which (650) 604-0262 vehicles. Analysis was made on the would be used for onboard diagnosis [email protected] exhaust plume data collected from for health management, and could the Space Shuttle main engines. The represent a safety check for the analysis capability is to give indica- space vehicle crew. A much more tions of engine erosion and its immediate benefit of the posttest potential source inside the motor. analysis is that it provides engineers,

132 P ROGRESS IN IMPROVING SPACE TRAVEL H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

involved in engine tear-down focused on lightweight methods, key static properties, and for correct activity following a test, a real which can be applied to small dynamic behavior. The figure shows indication of whether such an chunks of a specification without a an analysis of the timing behavior of expensive task is necessary. substantial investment in translating the FDIR requirements using the This project was the world’s entire specifications into mathemati- SPIN tool. first use of plume spectroscopy to cal notations. The formal methods allowed produce realistic, quantified esti- A series of case studies was the IV&V team to quickly identify mates of metal erosion from a rocket conducted, applying formal model- numerous weaknesses in these engine. During recent routine testing ing techniques to ‘live’ projects, so requirements, including ambiguous of a main Space Shuttle engine at the that the results can be fed back into use of terminology, missing require- Stennis Space Center, the analysis the project in time to be of added ments, and inconsistencies in the tools coupled to data from a diag- value. The case studies were chosen timing requirements. These problems nostic instrument were able to in response to real needs on existing would normally not be detected determine metal erosion taking place projects; for example, where an until later in the development and pinpoint the event of a cata- additional level of assurance of the process, at which point the costs to strophic failure. The methods used correctness of the requirements was correct them are significantly higher. in the analysis were even able to needed, over and above that obtain- Results indicated that the main extract silver and copper lines, able through existing methods. The effort involved in applying the despite the fact that they were case studies completed in the past formal methods is in translating the swamped in the rich hydroxyl year related to the International prose requirements into the formal grouping (OH) structure of the Space Station. A range of different notation. However, this effort is spectrum. formal methods was applied, consistent with the level of effort including software cost reduction, normally applied to performing Point of Contact: T. Patel the prototype verification system, IV&V on critical functions. In (650) 604-4721 and the model checker software contrast, the ability to spot errors [email protected] process improvement network and omissions is greatly improved, (SPIN). In each case the amount of as over half the issues identified in effort required to apply the method the formal analysis could not be was examined, along with the types detected during the requirements Formal Lightweight of benefits gained. This evaluation phase using existing methods. Approaches to Validation was mainly qualitative, as the Hence, formal methods provide a baseline metrics do not exist for cost-effective approach to analyzing of Requirements detailed quantitative comparisons. requirements, provided they can be Specifications The analysis conducted during focused. Steve Easterbrook the case studies provided a signifi- Formal methods have not yet cant addition to the IV&V performed gained widespread acceptance by The objective of this research on the Space Station SRS. A major software practitioners. Part of the was to evaluate the use of formal case study examined the require- problem has been an emphasis on methods as a tool for independent ments for the fault detection, isola- adopting a baseline formal specifica- verification and validation (IV&V) of tion, and reconfiguration (FDIR) for tion, from which to prove that design software requirements specifications the main communications bus on and implementation are correct. (SRS) for spacecraft flight software. the space station. This study This project has demonstrated that Formal methods allow an IV&V team involved translation of the original a more realistic approach is to use to test SRS for properties such as prose requirements into a formal, formal methods for small pieces of consistency, completeness, safety, tabular notation, and analysis of the modeling, especially during the early and correctness. The research resulting model for consistency, for

P ROGRESS IN IMPROVING SPACE TRAVEL 133 Fig. 1. A screen snapshot from the SPIN tool, showing the FDIR system (center) interacting with other subsystems (the clock, a test harness, and the hardware it controls). This analysis allows the analyst to confirm that the software will behave in the intended fashion even before it is written; that is, based solely on a statement of the requirements.

134 P ROGRESS IN IMPROVING SPACE TRAVEL H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

requirements stages, to answer Subjects were given two tests, each subjects were instructed to alter- questions that cannot be addressed 50 minutes long, one test before and nately increase and decrease in other ways. one test after AFTE. Physiological response levels (for example, heart data were continuously recorded rate accelerations and decelerations, Point of Contact: S. Easterbrook during both tests with the Autogenic- peripheral vasodilatation and (304) 367-8352 Feedback System-2 and impedance constriction, etc.). A 6-minute resting [email protected] cardiography. The protocol for these baseline was also collected after tests is outlined as follows: each session (total 42 minutes). 1. Supine resting 10 minutes The purpose of these training ASTRONAUT HEALTH/ ASTRONAUT HEALTH/ baseline sessions was to provide subjects ␣␣COUNTERMEASURES COUNTERMEASURES 2. Head-up tilt at 10 minutes with the ability to recognize bodily 50 degrees sensations associated with both 3. Supine resting 10 minutes increases and decreases in their Autogenic-Feedback baseline physiological response levels and, Training as a Potential 4. Head-down tilt at 10 minutes with practice, to improve their skill Treatment for Postflight –30 degrees in controlling these responses. 5. Supine resting 10 minutes Subjects eventually learn to maintain Orthostatic Intolerance baseline their physiological response levels at Patricia S. Cowings, Each subject received 6 hours or near their own resting baseline William B. Toscano of AFTE, which was administered in levels and improve their tolerance twelve 30-minute sessions (with to environmental stressors (for The goal of this research is to subjects sitting; that is, nontilt example, tilt table, conditions of determine if human subjects can conditions). Following a 6-minute microgravity, etc.). learn to voluntarily control blood pretest baseline, each 30-minute The first figure shows a subject pressure increases during a gravito- training session was divided into in the head-down tilt position. The inertial stimulus (for example, tilt ten 3-minute trials, during which table), and to determine the mechanisms by which such control is effected. The training method used, Autogenic-Feedback Training Exercise (AFTE), was initially developed as a treatment for motion sickness. It involves teaching subjects to control voluntarily up to 20 of their own physiological responses simultaneously. In support of the present study, cardiovascular dynamics (derived from impedance cardiography) were measured and displayed to test participants in real time. These measures included: cardiac output, stroke volume, and an estimate of vagal tone. Tests are in progress; this report outlines the results obtained to date. Baseline data were collected on each subject during supine, head-up tilt, and head-down tilt conditions. Fig. 1. Subject during 30-degree head-down tilt.

A STRONAUT HEALTH / Countermeasures 135 second figure shows physiological Cardiac Output responses of cardiac output (top Subject #1 Before AFT chart) and heart rate and blood After AFT pressure (bottom chart), before and 8 after AFTE. This subject made a significant increase in both heart rate and cardiac output in response to 6 head-up tilt (minutes 11 through 20) after eight AFTE sessions. There was

Liters/min no observable change in cardiac

4 output during tilt before training. The third figure shows the physiological data of one subject during AFTE sessions four (after 2 1 10 19 28 37 46 almost 2 hours of training) and eight (after almost 4 hours of training). The Minutes data shown include finger pulse volume, respiration rate, heart rate, Heart Rate and Blood Pressure* skin conductance level, cardiac 100 Subject #1 170 output, stroke volume, central volume (actually thoracic imped- 90 ance), and an estimate of vagal tone 140 (calculated by Fast Fourier Transform 80 in real time). Following the 6-minute baseline, subjects were instructed to produce arousal responses (constric- 70 110 tion of finger blood volume, heart- mmHg

Beats/min rate and skin-conductance-level 60 increases) but not to modify respira- 80 tion or to contract muscles. More 50 consistent control of finger pulse volume was apparent during session eight than during session four— 40 50 1 10 19 28 37 46 as the subject makes the desired Minutes response at 3-minute intervals. Respiration was recorded to show * Blood pressure was taken after AFTE only. On the bottom chart, diamonds represent systolic blood pressure and squares that the subject was neither hyper- indicate diastolic blood pressure (read on right axis). nor hypoventilating (by session eight) to influence other response Fig. 2. Physiological responses to tilt before and after AFTE. changes. By session four, both heart rate and skin conductance level show evidence of learning that remained consistent through session eight. Note, however, that learned control of cardiac output, stroke volume, and vagal tone was not

136 A STRONAUT HEALTH / Countermeasures H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

AFT #4 Subject #1 AFT #8

1200 Finger pulse volume 22 Respiration rate 1000 20 8000 18 16 6000

Units 14 4000 12 Breaths/min 2000 10 0 8 1 4 7 10 13 16 19 22 25 28 3134 37 40 1 5 9 13 17 21 25 29 33 37 41

12 Heart rate 50 Skin conductance level

10 45 40 8 35 Mhos/min Beats/min 6 30 4 25 1 5 9 13 17 21 25 29 33 37 41 1 5 9 13 17 21 25 29 33 37 41 12 Cardiac output 180 Stroke volume 11 160 10 9 140 8 120 7 100 Liters/min 6 Ohms - cm 5 80 4 60 1 5 9 13 17 21 25 29 33 37 41 1 4 7 10 13 16 19 22 25 2831 34 37 40

35 Central volume 140 Vagal tone 34 120 33 100 32 80 31 60 Ohms

30 Est. power 40 29 20 28 0 1 5 9 13 17 21 25 29 33 37 41 1 4 7 10 13 16 19 22 25 2831 34 37 40 Minutes Minutes

Fig. 3. Physiological responses during AFTE sessions four and eight. Note: Following a 6-minute resting baseline, subjects are instructed to produce alternating arousal (that is, constriction of blood flow to the fingers, heart-rate and skin-conductance-level increases) and relaxation responses (that is, vasodilation of fingers, decreases in heart rate and skin conductance level) at three 3-minute training trials, showing for the first time that these parameters may be subject to learned, voluntary control.

A STRONAUT HEALTH / Countermeasures 137 apparent until session eight, suggest- date has lacked sufficient loads to bed rest- and microgravity-induced ing that AFTE practice is associated maintain preflight musculoskeletal deconditioning by simulating with observed response changes. mass. Although treadmill exercise gravity. (See the figure.) The LBNP Central volume was also modulated with bungee cords (about 2 hours exercise device consists of a verti- with instruction (that is, at 3-minute per day) is the most common cally oriented treadmill within a intervals) more consistently after exercise for cosmonauts during long- partial-vacuum chamber that is eight sessions. duration Mir missions, biomechani- sealed around the subject’s lower These data represent the first cal loads on musculoskeletal tissues body. For use on Earth, supine indication that these measures of of the lower body are only about subjects are supported by a suspen- cardiac dynamics are subject to 60␣ to 70% of those present on Earth. sion system of cables and pulleys. voluntary control through learning. Theoretically, an integrated counter- Suction pressure is used to pull They show that AFTE methods may measure for extended exposure to blood and other body fluids away yield a powerful, potential counter- microgravity should combine high from the heart (thus reproducing measure for postflight orthostatic loads on the musculoskeletal system normal upright blood pressure intolerance that may supplement with normal regional distributions of gradients) while simultaneously existing exercise routines utilized by blood pressure and stimulation of creating a gravity-like footward crewmembers. normal neuromuscular locomotor force. patterns. In a recent study, it was hypoth- Point of Contact: P. Cowings Lower-body negative pressure esized that daily LBNP exercise (650) 604-5724 (LBNP) exercise is an integrated maintains cardiovascular and [email protected] countermeasure that may prevent musculoskeletal conditioning during

Exercise for Long- Duration Spaceflight Donald E. Watenpaugh, Richard E. Ballard, Karen J. Hutchinson, Jaqueline M. William, Andrew C. Ertl, Suzanne M. Fortney, Lakshi Putcha, Wanda L. Boda, Stuart M. C. Lee, Alan R. Hargens G x (Earth gravity) Adaptation to microgravity leads to cardiovascular and musculoskeletal deconditioning to normal Earth gravity. Specific problems include muscle atrophy, bone demineraliza- G z tion, reduced neuromuscular (LBNP suction force) coordination, and postflight reduction of orthostatic tolerance and upright exercise capacity. Presently, Fig. 1. Treadmill reaction force to generate body weight in supine posture exercise protocols and equipment equals the product of the cross-sectional area of the flexible waist seal and for astronauts in space are unre- the suction pressure within the LBNP chamber. With exercise, inertial solved, although recent calculations reaction forces against the treadmill are added to the static force. suggest that all exercise in space to

138 A STRONAUT HEALTH / Countermeasures H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE

6-degree head-down bed rest. Seven cardiovascular and musculoskeletal Research and Development Center, healthy male volunteers acted as fitness while reducing the duration the Keiser SX-1 resistance exercise their own controls, such that their of astronaut exercise sessions. device was developed to prevent responses to 2 weeks of bed rest muscle atrophy and bone weakness. Point of Contact: A. Hargens with daily supine LBNP treadmill Two pneumatic pistons provide (650) 604-5746 exercise (40 minutes of walking and variable and high resistance for the [email protected] running at 1.0 to 1.2 body weights of lower-body exercises, whereas a footward force) were compared to single piston allows resistance their responses to 2 weeks of bed exercises for the upper body and rest with no daily exercise. The spine. When performing the exer- 2-week bed rest sessions were Keiser SX-1 Variable cises, the user is secured by a separated by 10 weeks. Resistance Exercise Device harness to provide muscle isolation Forty minutes per day of LBNP and proper positioning (see the first exercise preserved upright exercise Jennifer Pedley, Anthony Artino, figure). The device includes an capacity during 2 weeks of bed Richard Ballard, Alan R. Hargens adjustable monitor that provides rest. Subjects’ time to volitional feedback information such as force, Muscle atrophy and decreased exhaustion during their individual- work, and power. Other features bone density are problems associ- ized treadmill tests decreased include strength and cardiovascular 1.72␣ minutes on average (10%, ated with extended exposure to modes represented on the monitor. microgravity. Therefore, it is vital for p < 0.05) after bed rest with no daily In the strength mode, the monitor astronauts to exercise during long- exercise; daily LBNP exercise during displays the number of repetitions bed rest maintained exercise toler- duration spaceflight to reduce these and the angle of the upper-body adverse physiological changes. In ance time at pre-bed rest levels. exercise levers. The cardiovascular collaboration with Ames Research Daily LBNP exercise also maintained mode conveys to the user repetitions peak upright oxygen consumption Center and Palo Alto Veterans per minute, total time of the exercise Administration Rehabilitation (VO2) at pre-bed rest levels (pre-bed rest: 59.5 ± 3.2 milliliters/minute/ kilogram; post-bed rest: 56.4 ± 3.4). Mean peak VO2 decreased significantly from 57.6 ± 2.6 to 49.8 ± 1.5 milliliters/minute/kilogram after bed rest with no exercise. Sprint speed from a standing start was maintained at pre-bed rest levels when daily LBNP exercise accompanied bed rest (pre-bed rest: 5.5 ± 0.2 meters/second; post-bed rest: 5.2 ± 0.3). However, bed rest without daily LBNP exercise significantly reduced sprint speed from 5.5␣ ± 0.2 to 4.6 ± 0.3 meters/ second, below pre-bed rest control levels. In conclusion, LBNP exercise improves upon current spaceborne exercise technologies by supporting Fig. 1. The Keiser SX-1 in an unfolded configuration.

A STRONAUT HEALTH / Countermeasures 139 for upper and lower body, and lower back postural muscles; and to the calf muscles, gastrocnemius graphic indicators to represent the (6)␣ bilateral or unilateral hip flexion. EMG activity was greater with the range of motion. The Keiser SX-1 In addition, many of the above SX-1 than the SLP, while soleus EMG is designed to fit into a standard exercises produce spinal loading that activity was similar or slightly lower Space Station rack. The total weight may help reduce back pain due to with the SX-1 than the SLP. These of the device is 120 kilograms spinal lengthening in microgravity. results indicate that the Keiser SX-1 (265␣ pounds), but the weight can be In a comparison evaluation with is capable of loading thigh and calf reduced to 80–100 kilograms using a standard supine leg press (SLP) muscles in a manner similar to a aluminum. device, the SX-1 demonstrated conventional leg press device used All exercises are performed in similar thigh muscle electromyo- for ground-based exercise. one or two positions by using the graphic (EMG) activities during Presently, cardiovascular four buttons located on the concentric and eccentric exercises machines are emphasized on the handgrips. Two thumb buttons on (see the second figure). With regard Space Shuttle; however, strength each handgrip are capable of adjusting (1) the amount of resistance to the upper and lower 100 SX-1 extremities; (2) the leverage from a SLP pulling to pushing exercise (that is, pulldown to a chest press); and * (3)␣ the range of motion for arms 75 from 0 to 70 degrees (that is, row to shoulder press exercise). Maximum and minimum resistance values for * 50 the lower-body range from 1,500 to 100 Newtons and for the upper body

from 1,000 to 50 Newtons. At any EMG activity (%max) designated time, the user can adjust 25 the resistance and exercise. A user can perform resistance exercises from supine and prone positions. These exercises include: 0 Con Ecc Con Ecc Con Ecc (1) bilateral chest press for strengthening the pectoralis major, anterior Vastus medialis Vastus lateralis Rectus femoris deltoids, and triceps; (2) bilateral row for strengthening the latissimus * denotes significant difference between SX-1 and SLP (p < 0.05). dorsi, rhomboids, and biceps; (3)␣ bilateral shoulder press, supine Fig. 2. Average thigh muscle electromyographic (EMG) activity in 11 and/or prone position for strengthen- subjects for the concentric (Con) and eccentric (Ecc) phases of contraction ing the deltoids and triceps; during a 10-repetition maximum leg press exercise using the Keiser SX-1 (4)␣ bilateral lat pull-down, supine and conventional supine leg press (SLP). In general, EMG activities were and/or prone position for strengthen- similar between the SX-1 and SLP, with the exception of concentric ing the latissimus dorsi and biceps; contractions of the vastus medialis and rectus femoris. This difference is (5)␣ bilateral or unilateral leg press for probably related to a lesser load placed on these muscles using a variable strengthening the gluteals, quadri- pneumatic resistance for the SX-1 as compared to a constant weight ceps, hamstrings, calf muscles, and for the SLP.

140 A STRONAUT HEALTH / Countermeasures H UMAN EXPLORATION AND D EVELOPMENT OF SPACE ENTERPRISE training devices are an exception. Dehydration at Airline determine if rehydration drinks Exercising on a variable-resistance Cabin Altitude (AstroAde (AA), Performance 1 (P1), device during spaceflight may be or water (H2O)) could ameliorate effective in decreasing the detrimen- John E. Greenleaf, Peter A. Farrell, the hypovolemia in 10 young men tal physiological effects caused by Helmut Hinghofer-Szalkay (21 to 30␣ years old, weighing 62 to exposure to microgravity. Keiser SX-1 101␣ kilograms) sitting (with light has the ability to combine cardiovas- A contributory factor for the activity) for 12 hours at 2800 meters cular and resistance training as well jet-lag syndrome in humans is total (9184 feet, 539 millimeters Mercury) as spinal loading during exercise. body dehydration, or hypohydration in an altitude chamber. With an appropriate high-resistance (see first figure), which is manifest After the subjects rested for training protocol, users may be by a reduction in plasma volume 10␣ hours in the chamber and able to maintain muscle size and (hypovolemia). Exposure to pro- consumed three normal meals strength as well as bone density. The longed chair-rest confinement and (2850␣ kilocalories, 1400 milliliters Keiser SX-1 represents an important possibly to moderate altitude (alt.), water), their plasma volume advance toward this goal. as occurs in passenger airline cabins, decreased significantly (p < 0.05) could facilitate this dehydration. by 9.0% (AA, alt.), 6.2% (P1, alt.), Point of Contact: A. Hargens The purpose of this study was to 7.4% (H O, alt.), and 9.0% (H O, (650) 604-5746 2 2 [email protected]

Confinement Cabin environment Anxiety deconditioning

Caffeine Increased blood Reduced exercise intake pressure sitting body position Increased heart rate

Increased Decreased fluid urinary output & food intake Alcohol intake Lower extremity Low humidity edema reduced pO2 increased airflow

Increased body Increased insensible water loss & respiratory (dehydration) fluid loss

Hemoconcentration (Hypovolemia)

Fig. 1. Factors affecting in-flight hypovolemia.

A STRONAUT HEALTH / Countermeasures 141 ground). (See second figure.) The 0 men then drank AA, P1, or H2O (8.3)* (12␣ milliliters/kilogram body weight, 948 milliliters at 16 degrees Centi- Ð2 grade). At 90 minutes (hour 120 after the 30-minute drinking period), (2.8) plasma volume had increased by Ð4 8.3% (AA, p < 0.05), 2.8% (P1, not significant), –0.9% (H2O, alt., not Drinking significant), and 0.8% (H2O, ground, Ð6 * not significant). These data indicate that signifi- * cant dehydration and hypovolemia Ð8 (Ð0.9) occur with adequate food and fluid * (0.8) intake during moderate (12-hour)

Plasma volume (HbÐHct) AstroAde Ð Altitude

∆ confinement (sitting) at moderate Performance 1 Ð Altitude * % Ð10 Water Ð Altitude altitude. Because plasma volume Water Ð Ground also decreased on the ground, it appears that confinement, and not Ð12 the moderate hypoxia, causes the Sitting hypovolemia and hypohydration. 0 2 4 6 81210 Point of Contact: A. Hargens Time (hrs) (650) 604-5746 * Significant (p < 0.05) decrease at hour 10, and significant percent increase at hour 12 (in parentheses). [email protected]

Fig. 2. Mean percent change in plasma volume at altitude and on the ground.

142 A STRONAUT HEALTH / Countermeasures Mission to Planet Earth Enterprise

144 M ISSION TO PLANET EARTH ENTERPRISE

O v e r v i e w and aquatic ecosystems; the chemical and transport processes that NASA’s Mission to Planet Earth determine atmospheric composition, (MTPE) studies the total Earth dynamics, and climate; and the environment—atmosphere, ice, physical processes that determine oceans, land, biota, and their the behavior of the atmosphere on interactions—to understand the the Earth and other solar system effects of natural and human- bodies. Of special interest are the induced, near-term changes on the development and application of global environment and to lay the new technologies required to bring foundation for long-term environ- insight to these science topics. ment and climate monitoring and Significant contributions were made prediction. Ames Research Center in three areas: analysis of critical supports the MTPE Enterprise by gaseous emissions, development of conducting research and developing models and instruments, and technology to expand the knowledge radiation research. of Earth’s atmosphere and ecosys- Research highlighted in this tems. This objective is also one of report includes focus on important the goals of NASA’s astrobiology environmental concerns related to research and technology efforts, stratospheric ozone depletion, which are led by Ames. A comple- perturbations in the chemical mentary objective is to apply the composition of the atmosphere, knowledge gained to practical, and climatic changes from clouds, everyday problems and to transfer aerosols, and greenhouse gases. the technology and knowledge to Numerous state-of-the-art instru- users outside NASA. Numerous ments were flown successfully, and research and technology efforts were significant data were collected for accomplished during FY96, and the stratospheric and tropospheric results address the following goals of research. For stratospheric experi- the MTPE Enterprise: ments, the following are included: the Meteorological Measurement ␣ ␣ • Expand scientific knowledge of System (MMS), which measures the Earth‘s environmental pressure, temperature, and the system. wind vector; and a dual-channel ␣ ␣ • Enable the productive use of tracer instrument for stratospheric MTPE science and technology. dynamics studies (Argus). ␣ ␣ • Disseminate information about These instruments were flown the Earth’s environmental on the ER-2 aircraft for the Airborne system. Southern Hemisphere Ozone Experiment and for the Stratospheric The research is particularly Tracers Atmospheric Transport concerned with atmospheric and (STRAT) study. For tropospheric ecosystem science and with bio- experiments, instruments were flown sphere/atmosphere interaction. Key on several aircraft to measure carbon components of the research include monoxide, nonmethane hydrocar- the study of physical and chemical bons, carbonyls, and reactive processes of biogeochemical nitrogen species. Specifically, cycling; the dynamics of terrestrial

145 fluxes of important biogenic gases Radiation research focuses on from terrestrial ecosystems were phenomena associated with the quantified, as were contrails of interaction of solar radiation with the subsonic aircraft and cloud effects atmosphere and solar system bodies. (SUCCESS) and tropospheric aerosol The high-resolution infrared spec- radiative forcing (TARFOX). troscopy is devoted to basic experi- Technology developments were mental and theoretical research into realized on two fronts—modeling the absorption of radiation by gases. and instruments. Model develop- The purpose is to determine the ment efforts or simulations based on molecular spectroscopic parameters developed models are presented for needed for the design and interpreta- the following phenomena: the effect tion of field measurement programs of gravity waves generated by related to the environment of Earth’s convection or stratospheric circula- and other planetary and stellar tion; the effects of climate and atmospheres. This report also landcover interactions in the boreal highlights experiments conducted biome; soil/atmosphere exchange with the Radiation Measurement of key trace gas species; biomass System and with a new within-leaf combustion and pyrogenic trace gas radiative transfer model. emissions; seasonal differentiation Using MTPE data and technol- of microbial methane sources; a ogy, commercial firms can expand knowledge-based, interactive, their businesses and public-sector graphical tool; use of supercomputer managers can exercise stewardship technology in ecosystem simulation; of the nation’s natural resources. and paleoenvironment studies using The enabling, productive use of pollen data and leaf area develop- MTPE science and technology is ment. Newly developed instruments exemplified by numerous accom- include: a miniaturized, lightweight, plishments including the effects of tunable diode laser spectrometer; an land-use change on the methods MMS on the NASA DC-8 aircraft to and assumptions currently in use to provide science-quality state vari- estimate the influence of land cover ables and wind data; an airborne in Earth’s carbon budgets of the disaster-assessment sensor; a digital northern boreal forest in array scanning interferometer; Oregon. Other reported data, and a fully automated, 14-channel analyses, and technologies can be sunphotometer to fly on remotely used by researchers who seek piloted aircraft and other platforms. answers to key Earth science ques- Also, a new program was created tions and by educators who teach (ERAST) to focus critical technology Earth sciences. development and flight demonstration for remotely piloted vehicles.

146 M ISSION TO PLANET EARTH ENTERPRISE

Ecosystem ECOSYSTEM ScienceSCIENCE AND Robert Higgins of SIMCO Electron- Bay Area Digital ␣␣TandECHNOLOGY Technology ics, Philip Riggan and Robert Lockwood of the U.S. Forest Service, Georesource and Chien Nguyen of Raytheon. Edwin Sheffner, Sheri Dister, AIRDAS—Use of Remote Recent activity has involved the Don Sullivan Sensing for Disaster user community, the U.S. Forest Assessment and Service, the California Department The Bay Area Digital of Forest and Fire Protection, the Los Georesource (BADGER) is a coop- Management Angeles County Fire Department, the erative project among NASA, James Brass, Vincent Ambrosia, Office of Emergency Services, and Lockheed Martin Palo Alto Research Robert Slye the Federal Emergency Management Laboratory, and a nonprofit organi- Agency to develop system require- zation called the Bay Area Shared Each year natural disasters in ments, review present capabilities, Information Consortium (BASIC). the United States cause an estimated and make recommendations for The goal of BADGER, funded 20 to 50␣ billion dollars in damage. system improvements. Major primarily by NASA’s High- Fires, earthquakes, floods, hurri- upgrades to the system, developed to Performance Computing and canes, and tornadoes destroy fill user-driven requirements, include Communication Program, is to thousands of structures, devastate additional onboard real-time display provide NASA data and technology resources, raise havoc with transpor- capabilities, a real-time downlink toward development of a system that tation and communication networks, capability, and improved user will make digital, geospatial data of and cause loss of life. The manage- interface software for data exploita- the San Francisco Bay Area available ment of these events is costly and tion. The system continues to be over the Internet. BADGER technol- difficult. The consequences of these integrated on users’ aircraft for ogy will serve as the basis for an disasters are evident, and they lend disaster monitoring and assessment. ongoing service operated by BASIC. themselves to monitoring, mapping, Currently, the system resides on BADGER contains three opera- and assessment by remote sensing. NASA’s Lear 24, but it has also tional functions, all of which are The goal of this applied research flown on P-3s, the Lear 35 and 31, designed to be performed on the project, funded by NASA’s Mission the KingAir 200, and a Navajo. Internet. First, BADGER provides a to Planet Earth Enterprise and the The system was used in Brazil in “clearinghouse” for information on U.S. Forest Service, is to develop, FY96 to detect and map deforesta- the nature, location, and cost of demonstrate, and transfer this tion and fire activity, and to fly geospatial data of the Bay Area. technology to value-added compa- disaster␣ monitoring missions in Geospatial data contain a distribu- nies and the user community. The California, New Mexico, and tional component, that is, data that development, based on the Airborne Arizona. The system is currently can be represented on a map. Infrared Disaster Assessment System being upgraded to provide higher- Geospatial data include, for (AIRDAS), a compact, multispectral resolution datasets and to increase example, images of the surface of scanner designed for quick aircraft the telemetry capability. the Earth from ground-based cam- integration and deployment, takes eras to satellite systems, digitized advantage of technology developed Point of Contact: J. Brass maps showing location of roads, in the Silicon Valley of California (650) 604-5232 parcels, transmission lines, and and government laboratories, to [email protected] water features, and thematic maps collect, analyze, and communicate of natural hazards or population information to disaster management distributions. BADGER allows users personnel. The research was per- to locate geospatial data quickly. formed in collaboration with Edward Second, BADGER provides a Hildum of Sverdrup Technology, mechanism for public and private providers of geospatial data to

E COSYSTEM SCIENCE AND TECHNOLOGY 147 market data to users. After a user has surface area of the site as pervious or the University of Brazilia; Theresa located data of interest, he or she impervious. The application also Campos of the National Center for will be able to place an order calculates the percentage of land in Atmospheric Research; Robert through BADGER that will access each category. The online applica- Higgins of SIMCO Electronics; and the dataset on the server of the data tion, designed by BADGER and Edward Hildum of Sverdrup Tech- provider, transmit the data to the operated by BASIC, is expected to nology. The research is supported by user’s machine, notify the user and increase compliance and lower costs NASA, the U.S. Forest Service, the the provider of completion of the for the public and the agency U.S. Aid for International Develop- transaction, and bill the user for the administering the law. The second ment, the Instituto Brasiliero de Meio data delivered. Lastly, BADGER application developed by Ames staff Ambient e dos Recusos Naturais provides online applications to the allows users to locate a parcel in the Renovaveis, the Brazilian National user, that is, procedures by which a Bay Area and display it in relation to Space Institute, the Universities of user can overlay and manipulate categories of known natural hazards, Brazilia and Sao Paulo, and the layers of geospatial data to generate for example, flood, ground motion National Center for Atmospheric an information product—fundamen- during earthquakes, and wildfire. Research. tal, online, geographic information BADGER is one way in which Since 1992, aircraft campaigns system functions. NASA data and computational have focused on the savannas of the Project personnel contributed to technology are being used to serve central portion of Brazil. Collecting BADGER by development and commerce and real user needs, and remote sensing and trace gas implementation of the BADGER/ to demonstrate the utility and measurements, the campaigns have Internet home page interface; practicality of the Internet. documented greenhouse gas genera- development of secure, robust tion, nutrient movement, and cloud Point of Contact: E. Sheffner transaction protocols that allow condensation nuclei development in (650) 604-0021 BADGER users to access data on fires throughout the central Brazilian [email protected] public and private servers; develop- grasslands. The fire data continue to ment of software for interactive document the variability in flaming location of parcels using street and smoldering conditions within addresses or assessors’ parcel the cerrados, with rates of spread numbers; and development and Brazil/United States between 0.1 and 3.0 meters per implementation of specific BADGER Environmental Monitoring second and smoldering conditions applications. and Global Change lasting from 15 minutes to over Two applications were demon- 3␣ hours. Consistency in emission strated in FY96. The “Notice of Program factors for nitrogen and carbon Intent” application, developed for James Brass, Vincent Ambrosia species continues, depending on the the Santa Clara Valley Water fuel type and condition. District, allows the owner/operator This program involves a The FY96 campaign focused on of a commercial enterprise to multidisciplinary team of interna- deforestation for the first time. Data comply with a section of the clean tional researchers performing from flights of the Airborne Infrared water act by filing information cooperative studies to identify and Disaster Assessment System over the electronically about the nature and mitigate the extent and environmen- Amazon basin and dry tropical forest destination of runoff from the site. tal effect of deforestation and documented large areas of cutting, The application completes a form burning within the dry and wet similar to that of the Pacific North- and supplies three images showing tropical forests of Brazil. This west of the United States. The sensor the location as outlined on a digital research is performed in collabora- system was able to discriminate orthophoto quad (aerial photograph) tion with Philip Riggan of the U.S. between the two major types of and map sheet, and an image Forest Service; Joao Pereira, Heliosa cutting (clearcuts and selective showing the classification of the Miranda, and Antonio Miranda of

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harvesting), where individual high- porary patterns and processes of of about 6 teragrams (1012 grams) of value species are removed from the ecosystem trace gas exchange N-N2O per year and 10 teragrams of site. between the terrestrial biosphere and N-NO per year from soils worldwide Although the deforestation is the atmosphere. The CASA model is (as illustrated in the figure (see Color important from many standpoints, unique in that it now simulates a Plate 21 in the Appendix)), exclusive the missions during August and host of trace gas fluxes (carbon of N fertilizer sources. While tropical September of 1996 concentrated on dioxide (CO2), methane (CH4), forest ecosystems contribute over the impact of harvesting on fire carbon monoxide (CO), nitrous 50% of global annual N2O emis- occurrence and behavior. Two types oxide (N2O), and nitric oxide (NO)) sions, cultivated areas are potentially of burning occur after harvesting of on a scale that merges remote significant sources on a regional timber. If the area is clearcut, the sensing, climate, radiation, vegeta- basis. The next research goal that resulting fire is intense and leaves a tion, and soils datasets with nutrient builds on the CASA foundation is to visible fire scar that can be observed transformation processes at the level discern the manner by which to using remote sensing. If the area is of the soil microsite. This research represent and apply fertilized soils selectively harvested, fires occurring was performed in collaboration with and associated trace gas emissions. after the cutting are less intense and Pamela Matson of the University of Point of Contact: C. Potter leave no telltale sign of a fire scar California, Berkeley, Peter Vitousek (650) 604-6164 because the overstory left behind of Stanford University, and Eric A. [email protected] obscures the scar evidence. Davidson of the Woods Hole The FY96 campaign provided Research Center, Massachusetts. the data necessary to determine the The model has been refined relationship between harvesting, fire over the past year to run on either a activity, and greenhouse gas genera- daily or a monthly time interval to Digital Array Scanning tion. These remotely sensed data are simulate seasonal patterns in carbon Interferometer being analyzed and will help fixation, nutrient allocation, litterfall, Steve Dunagan, Philip Hammer quantify the amount of harvesting soil nitrogen mineralization, CO2, that is occurring in each ecosystem CO, N2O, NO emission, and CH4 and the resultant fire emissions. This and CO uptake in soils. In FY96, a A scanning interferometer, the digital array scanning interferometer information will be used to support new global application of the CASA (DASI), has been designed and the ongoing effort in Brazil to model, the hypothesis that variability fabricated for use in remote sensing inventory the amount of greenhouse in the ratio of N2O:NO emissions of the ecosystem. The interferometer gases being produced by biomass over broad spatial gradients depends is based on charged-coupled-device combustion. upon seasonal patterns of soil wetting and drying, was examined. It sensor technology, providing Point of Contact: J. Brass spectral sensitivity over the range appears that gross rates of nitrogen (650) 604-5232 from 0.4 to 1.0 micron. Light from mineralization account for major [email protected] differences in gas emissions among the ground scene is focused by means of an objective lens to an ecosystem types. This finding has entrance slit aperture oriented advanced the state of nitrogen (N) trace gas modeling notably by normal to the scanning (flight) Carnegie/Ames/Stanford direction. After passing through the calculating indices of the global slit aperture, the light is collimated Approach Model distribution of N cycling processes and divided using polarization optics Christopher Potter and estimating trace gas emissions into equal amplitude polarization based directly on those quantified vectors oriented along the ordinary The Carnegie/Ames/Stanford mineralization fluxes. and extraordinary axes of a Approach (CASA) model was The latest version of the CASA developed for the study of contem- model predicts a total emission flux

E COSYSTEM SCIENCE AND TECHNOLOGY 149 Hawaiian Pathfinder DASI Instrument Block Diagram

fast wide pressure canister to maintain 1 atm for SCSI +5, +12v convective coding of electronics SCSI Hard disk RS-433 SBC System +12v ± DASI +5, 12v health Canister P, sensor I/O monitor T sensors +5v RS-170 camers Serial

DASI optics parallel

Video switch I/O card Framegrabber Cooling fans Slit PCI/ISA passive back plane adjustment +5v ± heaters 15v Data acquisition computer Thermostat

Pitch Autoregulating switches correction FOG Scene +5, ±12v +24v +24v system gyro video +15v ± ± Galvonometer camera DC to DC power converters: 15, 12, 5VDC

window BNC video 41 pin 20 gage connector connector 100 to 24 VDC Platform RS-232 power converter aircraft Ground RS-170 GPS operator Telemetry terminal receiver Telemetry 100 VDC main tranceiver power bus Video Video monitor receiver Video transmitter Video 9600 baud recorder Time & GPS stamp modem

Fig. 1. Hawaiian Pathfinder DASI instrument block diagram.

Wollaston prism. The two polariza- an interferogram identical to the The detector array, consisting of tion vectors are then recombined, output of a scanning Michelson 240 by 750 pixels, may be config- collimated, and focused to the array interferometer. The interferogram ured along with the optics in several detector, where an interferogram is dimension (columns) of the array different ways to optimize spectral formed. Ordinary and extraordinary may then be Fourier transformed to bandwidth and emphasize either rays experience a path length yield the spectra of light originating spectral or spatial resolution. The variation across the prism aperture. from a ground pixel defined by the array output is digitized at 10 bits. At the zero path difference location, projection of the slit width and the The primary design configuration the rays interfere constructively, array column width. Rows of the provides a spectral range from 0.5 to regardless of wavelength, giving rise array provide the spatial distribution 1.0 micron, with theoretical spatial to a central peak intensity. On either of information along the slit. Scan- resolution of 4.3 meters in the flight side of this center burst wavelength, ning the slit in the flight direction direction and 2.5 meters cross track dependent interference gives rise to sweeps out an image hypercube.

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(at a 50,000-foot altitude), and Effect of Landuse on When moving from the plot scale theoretical spectral resolution of (30 square meters) to climate model 13␣ nanometers at 0.5 micron and Regional Estimates of scale (1-degree cells), errors of up to 50␣ nanometers at 1.0 micron. (Note Coniferous Forest Water 25 to 30% in regional water use and that the interferometer samples at and Carbon Budgets carbon cycling are observed for equal intervals in wavenumber coniferous forests in the western Joseph Coughlan, Jennifer Dungan space, resulting in a variation of United States. wavelength resolution that scales Additionally, there is usually a Geographic information systems approximately with lambda2). mismatch between the size and (GISs) and ecosystem models are The instrument has been shape of the units representing the common tools that “scale up” interfaced to a data acquisition landscape data used to make the measurements from ecological field system and packaged in a pressur- regional estimates, but many experiments across landscapes, ized container for deployment on a researchers are unfamiliar with this continents, and even the entire high-altitude, remotely piloted error source. Project researchers globe. Many predictions about the aircraft. The self-contained system have begun to document this GIS causes and effects of global change requires less than 150 watts of error and its effect on landscape- on the environment employ this power and weighs less than 10␣ kilo- scale predictions made with ecosys- scaling method in combination with grams. The data acquisition system tem models. The two most common remotely sensed data. NASA’s field comprises an industrial board level data layers are remotely sensed experiments in grasslands (the First computer, with an Intel Pentium vegetation represented as a digital International Satellite Land Surface 100-megahertz processor, protocol image of 1-kilometer-(0.63-mile-) Climatology Project Field Experi- control information (PCI) bus, and long cells and large polygons ment) and in northern forests (the 256 megabytes of system random- mapping soil types that the GIS Boreal Ecosystem Atmospheric access memory for direct memory translates into a digital format. Unit Study) are two examples of the need access storage of hypercube data. A size issues have important implica- to match the scale of ecological field digital framegrabber and a small tions consequences for the use of measurements with remote-sensing computer serial interface (SCSI) disk soils data because soil map units data. controller interface to the main usually comprise spatial units much Remote-sensing data often come computer board through a PCI larger in size than the vegetation from coarse resolution (approxi- passive backplane. An onboard map units. mately 1 kilometer, or 0.63 mile) 4.3-gigabyte hard disk permits In FY96, a new method was remote-sensing instruments such as storage of up to 16 hypercube developed to control resizing of soils the National Oceanic and Atmo- datasets per flight. Data transfer is and vegetation units used to predict spheric Administration’s (NOAA’s) limited by the continuous streaming plant photosynthesis. This method advanced very-high-resolution write speed of the hard disk, permit- reconstructs the soils data so that radiometer (AVHRR) and, in the ting the acquisition of 5 to 10␣ inter- they are represented with “support” future, NASA’s Earth Observing ferogram frames per second. A similar to the remotely sensed System. The mismatch between the schematic diagram of the device is vegetation, the 1-kilometer size of the plots used in a field shown in the figure. (0.63-mile) grid cell. This reconstruc- experiment and the size of the tion method enables researchers to Point of Contact: S. Dunagan landscape units generated with this conduct controlled experiments (650) 604-4560 relatively coarse resolution data can with GIS data at several spatial [email protected] cause scaling errors and result in an resolutions. overprediction of carbon and water The method was implemented cycling rates. Researchers in this with a federally sponsored soils project are quantifying this unit-size database for the state of Oregon and error in a set of scaling experiments.

E COSYSTEM SCIENCE AND TECHNOLOGY 151 a NOAA AVHRR image. The figure community, and to act as a reposi- To address this factor, a within- (see Color Plate 22 in the Appendix) tory for comments from the commu- leaf radiative transfer model (Leaf shows two maps of soil water nity on the current and future Experimental Absorptivity Feasibility holding capacity (SWHC) for a operation of the program. The task is Model, or LEAFMOD) has been portion of the state. The top map accomplished through the use of a developed and tested against shows the homogeneous polygons Landsat Program home page on the empirical data. The model simulates commonly used to spatially repre- Internet. The home page was the photon scattering and absorbing sent soil variables. The bottom map initiated in FY95; in FY96, extensive processes within the leaf, based shows the result of the new method revisions and additions were made. upon solution of the one- for SWHC. Using this new map Updated regularly with news items dimensional radiative transfer resulted in an underestimation bias about the program, the page con- equation, assuming a slab of leaf of 11% in plant photosynthesis tains links to similar pages in the material with homogeneous optical estimates for Oregon. The fact that United States and abroad. Approxi- properties. When run in the forward results can vary significantly using mately half the users who log on to mode, LEAFMOD generates the leaf the same model and data raises the home page are from outside the bidirectional reflectance and trans- serious issues for understanding United States. An online question- mittance profiles given a specified regional and global effects of climate naire was also added in 1996 that leaf thickness, optical characteristics change. will allow users to provide specific (scattering and absorption profiles) of information on the program leaf constituents, and concentrations Point of Contact: J. Coughlan electronically. of leaf constituents. In the inverse (650) 604-5689 mode, LEAFMOD computes the total [email protected] Point of Contact: E. Sheffner within-leaf absorption and scattering (650) 604-0021 coefficients from the measured leaf [email protected] thickness, reflectance, and transmit- tance. Inversion experiments with Landsat Program real and simulated data demonstrated that the model appropriately Edwin Sheffner Leaf Modeling decouples scattering and absorption The Landsat Program is the Lee F. Johnson, Chris Hlavka, processes within the leaf. The model produced absorption longest running program to collect Philip D. Hammer, David L. Peterson and distribute satellite imagery of profiles for fresh leaves, with peaks Earth. The first Landsat satellite was The proper interpretation of a at locations corresponding to the launched in 1972, and the next in land surface reflectance detected by major absorption features of water the series, Landsat 7, is scheduled air- or satellite-borne remote-sensing and chlorophyll. Using available for launch in 1998. In the quarter instrumentation generally requires spectral data for grape leaves, the century of operation, the instruments corrections for distortions caused by magnitude of the absorption coeffi- on Landsat have transmitted millions the intervening atmosphere. If the cient profile in the visible region was of Earth images that have been signal originates from a vegetated strongly correlated to chlorophyll employed by a broad user commu- surface, corrections for canopy and concentration determined from nity for studies of global change, leaf anatomical structure are also conventional laboratory analysis. resource monitoring and assessment, needed. Although considerable Spectral data from a leaf-stacking local and regional planning, disease progress has been made in the and drying experiment demonstrated control, and education. development of models to isolate that absorption features related to The primary program support the influence of atmosphere and various biochemical constituents task at Ames Research Center is to canopy, less effort has been given to could be identified in the dry-leaf get information on Landsat to all distortion due to leaf structure. absorption profile derived by elements of the Landsat data user LEAFMOD.

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The model can be used to northern high latitudes, microbial of remotely sensed data, such as the evaluate fresh-leaf spectral sensitivity decomposition processes acting on Landsat thematic mapper (TM) to leaf chemistry, and also to these carbon stores will almost sensor. These encouraging results investigate the influence of both certainly lead to increased atmo- provide an order of magnitude leaf chemistry and leaf amount on spheric loading of carbon dioxide improvement in the accuracy of vegetation canopy reflectance. Barry (CO2) and CH4, thus potentially estimates of the areal extent of Ganapol, University of Arizona, enhancing the greenhouse phenom- wetlands in the BOREAS study collaborated with the Ames investi- enon even further. region. gators on this project. The areal representation of Point of Contact: V. Vanderbilt boreal wetlands, the source areas for Point of Contact: L. Johnson (650) 604-4254 CH , is poorly known on regional to (650) 604-3331 4 [email protected] global scales, particularly the areal [email protected] extent of bogs, fens, and open-water lakes and ponds. Various estimates of the areal extent of northern wetlands differ nearly sevenfold. Modern Ecosystems Mapping Northern These differences in global invento- Research: Effects of Ecosystems: Applications ries lead to large discrepancies in the Increased UV-B Radiation for Circumpolar Methane estimation of overall exchange of CH4 from northern sources and sinks Hector L. D’Antoni, J. W. Skiles Exchange because emission rates from the Vern Vanderbilt, Guillaume Perry, various individual land covers (fens, The link among these efforts is Joel Stearn bogs, open water, wetlands, and the process of stratospheric ozone nonwetlands) can vary by a factor of depletion and the consequent The goals of this project are to more than 100:1. increase of ultraviolet-B radiation improve estimates of the areal extent The analysis of results for the (UV-B) in the biosphere. Given the of northern, high-latitude wetlands Boreal Ecosystem-Atmosphere Study deleterious effect of excessive UV-B and to gain insight into the role of (BOREAS) shows that glitter, the in living organisms, it is imperative northern ecosystems in the global sometimes visually blinding sparkle to establish what effects, if any, are methane (CH4) budget and, in so of sunlight from water surfaces, produced by the current levels of doing, provide improved estimates provides a powerful signal uniquely UV-B. of global CH4 exchange. identifying inundated areas. These Using alfalfa (Medicago sativa The role of northern wetlands BOREAS results demonstrate that L.) as the experimental plant, several in global atmosphere/biosphere inundated areas may easily be hypotheses have been tested, interactions remains an unresolved separated from noninundated areas. including: (1) production of screen- but key factor in projecting climatic It is also possible to discriminate and ing pigments is stimulated by UV-B change in response to increasing accurately classify fens, open water radiation; (2) node elongation is atmospheric concentrations of areas, and forested areas because the affected by UV-B radiation; (3)␣ phe- greenhouse gases, such as carbon visually blinding glitter of sunlight nological stages (that is, flowering) dioxide and methane. Wetlands off ruffled water surfaces provides a are controlled by UV-B radiation; north of 45°N represent globally strongly angular signature reflection and (4) alfalfa plants grown under significant methane sources—the characteristic of wetlands. Conse- UV-B exclusion have higher chloro- organic carbon stored in the peat quently, these classifications and phyll concentration. In contrast with and soil beneath these ecosystems estimates of the areal extent of fens most of the work published in this exceeds that of any other biome on and open water areas are signifi- area of research, these experiments Earth. Since climatic warming is cantly more accurate than similar were carried out with sunlight as the predicted to be most dramatic in estimates based upon other sources only source of UV-B radiation.

E COSYSTEM SCIENCE AND TECHNOLOGY 153 Plants that were grown in a growth those of Moffett Field, at approxi- areas of information technology and chamber in June were transferred to mately the same latitude in the ecosystem science. a shed in the field and grown there Northern Hemisphere. As a demonstration, a grassland for 6 to 8 weeks. The shed provided This research was performed in ecosystem model is being used to two chambers with identical envi- collaboration with G. R. Daleo, simulate the Great Plains (GP) of the ronmental conditions except for the S. Burry, M. C. Lombardo, A. C. United States, an area of approxi- UV regime. Chamber 1 is fitted with Mayoral, P. Palacio, and M. E. Trivi mately 60,000 advanced very-high- a cellulose acetate screen that of the University of Mar del Plata, resolution radiometer pixels. Large removes 15% of the UV band Argentina; Roy Armstrong, J. amounts of data are necessary to irradiance to simulate a preozone- Corredor, and J. Morell of the initialize the model for operation on depletion environment. Chamber 2 University of Puerto Rico a geographical area of this size. Data is fitted with a polyester screen that (Mayaguez); and Jaime Matta of the required include soil types, plant removes the entire UV-B irradiance Ponce School of Medicine, Ponce, community information, and band. The experiments, run the past Puerto Rico. weather drivers. A major undertak- two summers, have validated all four ing is the establishment of data Point of Contact: H. D’Antoni hypotheses and led to new questions structures whereby the model can (650) 604-5149 and hypotheses. Data require access correct information for a [email protected] intensive statistical analysis before specified location, access stored publication. soils data, calculate intermediate A similar effort with the Univer- and state variables, and update sity of Mar del Plata in Argentina has biomass and soil-water variables on resulted in several outcomes. The Optimizing an Ecosystem a pixel-by-pixel basis across the time Antarctic spring-time “ozone hole” Model for Use on Parallel/ frame of the simulation. All this is to often reaches southern South be done while maintaining the America during the austral spring. Distributed Processors biological and ecological dynamics Data show that 15 to 18 days of the J. W. Skiles, Cathy Schulbach of the ecosystem(s) being simulated. three-month season have a low Computer science areas of stratospheric ozone concentration in The goal of this project is to emphasis are: (1) establishing Ushuaia (southern Argentina), while update models/codes based on protocols for rehosting scalar code ground-level UV-B records are current ecological knowledge with to vector supercomputers and concomitantly high. Negative state-of-the-art computer simulation distributed-processing super- correlation was found between technology. Such modifications will computers; (2)␣ validating metrics stratospheric ozone concentration decrease execution time, enabling for load balancing and processor and UV-B irradiance at ground level. simulation of larger geographical scheduling; (3) using different types Negative correlation is higher in areas and/or performance of more of ecological model codes (differ- the wavelength range of 289 to simulation experiments. Areas of ence equation, partial differential 307␣ nanometers, known to damage emphasis are in ecology and com- equations, correlation equation) in DNA, chlorophyll, indole acetic puter science, with the expectation the distributed environment; and acid, gibberelins, abscisic acid, and that techniques developed in this (4)␣ using automated tools to aid in other important plant growth project will serve as a blueprint for the rehosting process. molecules. the construction of future Earth Although most ecosystem An extended visit to Argentina system models that will be run on models include state-of-the-art resulted in the reflectance analyses supercomputers showing how ecological concepts, they employ and in daily measurements of processes can be coded for distrib- scalar coding that does not take solar irradiance in the 300- to uted processing. In addition, this advantage of the power of contem- 750-nanometer range in Mar del project is expected to enhance Ames porary computing platforms. Plata (38°S) that can be compared to Research Center’s expertise in the

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Rehosting these codes to super- function of vegetation, and use these indices that can be used in predic- computers entails restructuring the equations to “hindcast” (as opposed tive models of environmental code itself and using available to forecast) past vegetation from change. Thus, the data used to command-level instructions during fossil pollen sequences obtained parameterize these models will span compilation. from stratified sediment deposits. over 10,000 years rather than the Because of weather patterns and Many models used to predict the customary few decades and will the resultant plant communities on environmental future of Earth are help differentiate long cycle fluctua- the GP, it is possible that some driven by remotely sensed data of tions from meaningful trends of locations will have growing plants vegetation. Historical remote-sensing environmental change. while others will not. This scenario databases of vegetation reach back Point of Contact: H. D’Antoni sometimes causes a processor on a only a few decades. Such a time (650) 604-5149 multiprocessor supercomputer to be frame is not sufficient to appreciate [email protected] idle while others are processing the long-term environmental processes. plant growth part of the code. Paleoenvironmental data might help Activity in this project focuses on solve this problem. However, efficiently balancing the load of each paleoenvironmental data are not processor so that none are idle, compatible with remotely sensed Scientists’ Intelligent thereby decreasing the execution data and, hence, they are of limited Graphical Modeling time for the simulation experiment. use for modeling. Progress to date includes the The efforts in FY96 concentrated Assistant construction of interpolation algo- on the Oregon Pollen Transect, a Jennifer Dungan rithms for missing data, stochastic collection of modern pollen samples weather generation for 31 locations from central Oregon, taken every Over the past 30 years, scientific on the GP, and the establishment of 10␣ miles from Dayville in central software models have played an gaming scenarios for global change Oregon to Newport on the Pacific increasingly prominent role in the modeling, including the incorpora- coast, and crossing vegetation zones conduct of science. Unfortunately, tion of increases or decreases in of ponderosa pine, western juniper, implementation of scientific models temperatures and precipitation and fir and Douglas fir, western hemlock, can be difficult and time-consuming, the seasonal timing of precipitation alder, and sitka spruce. A predictive and software engineering support events. equation of remote-sensing vegeta- available specifically for construct- tion indices such as the normalized ing scientific models is scant. Point of Contact: J. Skiles difference vegetation index (NDVI) Scientists’ Intelligent Graphical (650) 604-3614 was completed. Vegetation in Modeling Assistant (SIGMA), an [email protected] Oregon has changed during the last interactive, knowledge-based, 50 years, and in some localities the graphical software development original floristic composition is environment, was created at Ames to difficult to determine from current fill this gap. SIGMA is designed to Paleoenvironmental evidence. To solve this problem, a help scientists rapidly prototype their Research database has been constructed with scientific models by simplifying modern pollen data produced construction, modification, and Hector L. D’Antoni between 1930 and 1949. These data reuse of modeling software, and to will help to recalibrate predictive provide a supportive computational The goal of this research is to equations of NDVI and other indices environment for exploratory model calibrate modern pollen data in and, in turn, these equations will building. terms of satellite remote-sensing data assist to hindcast Holocene (that is, In FY96, two well-known of modern vegetation, produce the last 10,000 years) vegetation models describing radiative transfer calibrated equations of pollen as a in vegetation canopies were added

E COSYSTEM SCIENCE AND TECHNOLOGY 155 to the SIGMA knowledge base. international workshops (December rado. The combined dataset will be Sensitivity experiments were con- 1993 and August 1995) sponsored used by NOAA in refining their ducted with these models to investi- by the World Climate Research budgets of these carbon species in gate the relative importance of Programme, are a key element in the the northern hemisphere, and in the model variables in a more systematic validation of the models to be used development and validation of at way than is usual with traditional to assess the possible impact of least two three-dimensional global programming languages. In addition, aircraft emissions on the atmosphere chemical transport models. two graduate students at separate in NASA’s Atmospheric Effects of Point of Contact: M. Kritz universities tested SIGMA over the Aviation Program (AEAP). (650) 604-5493 Internet. They were able to navigate Project activity in this area has [email protected] the data flow graph for the ecosys- been divided between the acquisi- tem model, query the knowledge tion and the application of airborne base for details on variables and radionuclide measurements for this equations, and build the rudiments purpose. Over the last decade, the of a new model. instrumentation has flown on more Reactive Nitrogen than 100 flights aboard NASA Point of Contact: J. Dungan Data from the Upper aircraft, including the C-130, C-141, (650) 604-3618 DC-8, and ER-2. For example, in the Troposphere and Lower [email protected] summer of 1994, the instrumentation Stratosphere was onboard the C-141 on 15 flights Hanwant B. Singh, Alakh Thakur, out of Moffett Field, acquiring a ATMOSPHERIC CHEMISTRY Peter Mariani Atmospheric Chemistry statistically significant climatology of the summertime vertical distribution NASA has launched a subsonic of radon over northern California. aircraft assessment program (SASS) Airborne Natural This dataset found extensive applica- to determine the effect of the current Radionuclide tion at the August 1995 World and future subsonic fleet on the Measurements in the Climate Research Programme Earth’s environment as quantitatively Development and (WCRP) Workshop, and is currently as possible. A key SASS objective is being used in the validation of the to assess the effect of nitric oxide Validation of Global NASA AEAP core model. (NO) emissions from subsonic A more extensive set of similar Three-Dimensional aircraft on atmospheric ozone (O3), Models airborne radon measurements was especially in the region of the upper obtained over the central and troposphere/lower stratosphere. A Mark Kritz, Stefan Rosner, western United States in the summer large number of airborne studies in Robert Chatfield, Leonard Pfister of 1996, flying aboard a NASA Lear the free troposphere (for example, jet. In addition to radon, measure- global troposphere experiment (GTE) As the sources, lifetimes, and ments of carbon monoxide (CO), and tropospheric ozone/stratospheric atmospheric behavior of natural carbon dioxide (CO2), and methane ozone (TROPOZ/STRATOZ)) and 7 32 radionuclides (for example, Be, P, (CH4) were made in cooperation lower stratosphere (for example, the 210 222 Pb, and Rn (radon)) are with the National Oceanic and Airborne Arctic Stratospheric generally well understood, compari- Atmospheric Administration (NOAA) Expedition II) have been performed son of their observed distributions Climate Monitoring Diagnostics in the last decade, and a sizable with model prediction is finding Laboratory, Boulder, Colorado, and body of data on reactive nitrogen increasing application in the devel- measurements of ozone (O3) were species has been collected from both opment and validation of the global made in cooperation with the hemispheres. Although these data models used to assess global change. National Center for Atmospheric have been, to a degree, analyzed as Such comparisons, the focus of two Research Facility, Boulder, Colo- individual datasets, no comprehen-

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sive analysis and synthesis has been improving predictions of future horizon and unblocked by clouds or undertaken. Tasks in this study are to climate, including greenhouse aircraft obstructions (for example, acquire, analyze, and interpret warming, ozone depletion, and tail, antennas). experimental data on reactive radiation exposure of humans and Data are digitized and recorded nitrogen species (along with ozone, other organisms. by an onboard data acquisition and hydrocarbons, and selected tracers) A fundamental measure of any control system. Real-time data that have been collected over the aerosol is the way it attenuates a processing and color display are last decade, with focus on the upper beam of light of various colors (that routinely provided. The science troposphere and lower stratosphere. is, wavelengths). This attenuation is dataset includes the detector signals, The aim is to provide an overall usually described in terms of the derived optical depths, detector synthesis of the present understand- quantity optical depth. The depen- temperature, sun tracker azimuth ing of reactive nitrogen chemistry dence of optical depth on light and elevation angles, tracking errors, and recommendations for future wavelength is the optical depth and time. Each instrument must field research, based on a compre- spectrum. maintain its radiometric calibration hensive analysis of available data. The Ames airborne (including window and filter trans- Analysis of these data was com- sunphotometers determine the mittance, as well as detector pleted in FY96 and the results are optical depth spectrum of aerosols responsivity and electronic gain) to being finalized. and thin clouds by tracking the sun within 1% in each spectral channel and measuring the (relative) intensity for periods of several months to a Point of Contact: H. Singh of the solar beam in several spectral year. (650) 604-6769 channels. The tracking head of each In July 1996, the first science [email protected] instrument mounts external to the flights of the 14-channel sun- aircraft cabin, so as to increase data- photometer (developed under the gathering opportunities relative to NASA Environmental Research in-cabin sunphotometers and also to Aircraft and Sensor Technology Airborne Autotracking avoid data contamination by cabin- Program) were made on the Pelican Sunphotometry window effects. Each channel (modified Cessna) aircraft of the consists of a baffled entrance tube, Center for Interdisciplinary Remotely Philip B. Russell, John M. Livingston, an interference filter, a photodiode Piloted Aircraft Studies during the James Hanratty, Damon Ried, detector, and an integral preampli- Tropospheric Aerosol Radiative Jill Bauman fier. The filter/detector/preamplifier Forcing Observational Experiment. sets are temperature-controlled to Atmospheric aerosols (suspen- Point of Contact: P. Russell avoid thermally induced calibration (650) 604-5404 sions of airborne particles compris- changes. Each instrument includes ing hazes, smokes, and thin clouds [email protected] an entrance-window defogging in the troposphere and stratosphere) system to prevent condensation (a play important roles in determining problem otherwise common in regional and global climates, the aircraft descents). Solar tracking is chemical composition of the atmo- achieved by azimuth and elevation Analysis of Stratosphere/ sphere, and atmospheric transport motors driven by differential sun processes. As knowledge has Troposphere Exchange sensors. In general, sun tracking is advanced in each of these fields, so achieved continuously, independent Leonhard Pfister, Henry Selkirk has recognition of the importance of of aircraft pitch, roll, and yaw, aerosols. As a result, national and Aircraft atmospheric sampling provided rates do not exceed international bodies have called for experiments require the support and approximately 8 degrees per second increased efforts to measure aerosol and the sun is above the aircraft advice of meteorologists to be properties and effects, as a means of successful. The purpose of this

A TMOSPHERIC CHEMISTRY 157 project is to analyze meteorological Use of Argus in Airborne Tunable Laser fields both during and after field experiments so as to maximize the Atmospheric Studies Absorption Spectrometer scientific return of the sampling Max Loewenstein Max Loewenstein, James R. Podolske campaigns. The emphasis in this project is to provide meteorological The Argus instrument, a tunable- The Airborne Tunable Laser satellite information as it pertains laser, infrared spectrometer, was Absorption Spectrometer (ATLAS) to stratospheric transport and designed to measure the long-lived instrument was designed and built in stratosphere/troposphere exchange tracers methane (CH4) and nitrous the mid-1980s to measure strato- processes. oxide (N2O) in the stratosphere up to spheric tracer fields from the ER-2 During FY96, Ames provided altitudes of 30 kilometers. The ratio high-altitude research aircraft. meteorological coordination for the of these two tracers as a function of During the decade of its operation, Stratospheric Tracers of Atmospheric altitude provides important informa- ATLAS has been used primarily to Transport (STRAT) ER-2 sampling tion on the dynamics of different measure the nitrous oxide (N2O) mission and the Tropical Ozone regions of the stratosphere: the surf tracer field on several campaigns Transport Experiment (DC-8 mis- zone, the tropical pipe region, and primarily focused on polar and sion). Three major STRAT field the polar region distinguished by its midlatitude processes in the strato- campaigns were undertaken. Back strong winter vortex isolation. sphere. N2O is a very long-lived trajectory analyses of STRAT data In June and September 1996, the tracer of stratospheric dynamics. yielded evidence that midlatitude new Argus lightweight N2O and Normally, chaotic-appearing cirrus shields can determine the CH4 instrument was completed and observations of molecular constitu- water vapor content of the lower- flown on balloon launches to higher ents of the atmosphere such as most stratosphere. Some simple than 30 kilometers from Ft. Sumner, reactive nitrogen (NOy), carbon cloud height algorithms that can be New Mexico (34 degrees N), the site dioxide (CO2), water vapor (H2O), used in real time for flight planning of the NASA National Scientific chloro-fluoro-carbons (CFC) and for the low-altitude (tropospheric) Balloon Facility. In June, the instru- others are “smoothed” by construct- ER-2 flights have been developed. ment performed flawlessly in an ing correlation diagrams of these These algorithms use a combination engineering sense, but no reportable observations plotted versus N2O. of meteorological analyses and data resulted because of inadequate These correlations then provide satellite imagery to determine the control of the diode laser mount important chemical and dynamical cloud altitude at any point in a temperatures. This control limitation diagnostic information on the state satellite image. was corrected in time for the Sep- of the atmosphere. Finally, it has been shown that tember launch. In September, all The ATLAS instrument took part the subvisible cirrus observed by the aspects of the Argus instrument in the continuing Stratospheric DC-8 south of Hawaii are probably performed well, and ascent and Tracers of Atmospheric Transport due to air that originates in descent profiles for N2O were (STRAT) campaigns, with field Micronesia and travels northward to obtained. The methane channel is deployments carried out in October the subtropical jet, eastward toward being brought up to operational 1995 and February, July, and Hawaii, and southward—following status.The Argus instrument has been September 1996. The instrument an upper tropospheric/lower strato- prepared and shipped to Juazeiro do continues to work flawlessly and spheric anticyclone. Norte, Brazil, for use in the Orbiter returns very-high-quality N2O tracer Maneuvering System tropical field data on all flights. ATLAS N2O data Point of Contact: L. Pfister campaign. continue to be the dataset of choice (650) 604-3183 for analyses carried out within the Point of Contact: M. Loewenstein [email protected] STRAT community. Data compari- (650) 604-5504 sons with the aircraft laser infrared [email protected]

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absorption spectrometer (ALIAS) and Convectively Generated completed. One of these, from the airborne chromatograph atmo- Gravity Waves Stratospheric Tracers of Atmospheric spheric trace species (ACATS) N2O Transport campaign, shows gravity presented at a July 1996 STRAT Leonhard Pfister waves with horizontal wavelengths workshop show that ATLAS data are of about 50 kilometers and vertical of the highest quality and are true to This work evaluates the influ- wavelengths of 5 to 10 kilometers. its stated 3% accuracy. ence of gravity waves generated by This result suggests that a simple During the Airborne Southern convection on stratospheric circula- “transient mountain at the tropo- Hemisphere Ozone Experiment and tion in the tropics. Each convective pause” conceptual model can the follow-on Stratospheric Tracers event emits a spectrum of gravity explain only part of the mesoscale of Atmospheric Transport campaign waves with a broad variation of gravity wave variance. Evidence was in 1995 and 1996, a comprehensive phase speeds. These waves will also found of inertia-gravity waves break at a variety of altitudes new dataset on CO2 and N2O in the with horizontal wavelengths of northern hemisphere extending from corresponding to these phase 1000␣ kilometers, consistent with the equator to 60 degrees N was speeds; when they do, they will studies that inferred horizontal accumulated. Several important exert a force at that altitude that can wavelengths using vertical profiles results have emerged from this new affect the overall circulation of the and inertia-gravity wave dispersion and unique dataset: Tropospheric air tropical stratosphere. Understanding relationships. carrying its normal seasonal cycle the nature of this force quantitatively Point of Contact: L. Pfister and secular trend of CO continu- is essential to obtaining a compre- 2 (650) 604-3183 ously enters the lower tropical hensive picture of the transport of [email protected] stratosphere and is rapidly (in about trace constituents such as ozone, as one month) transported to both well as the constituents that govern hemispheres. The mean age of the ozone production and destruction. observed midstratospheric air is The assessment of the importance of about 6 years. Pollutant exhaust these convectively generated gravity The ER-2 and DC-8 gases, which will be deposited by waves has two steps: evaluation of Meteorological proposed new stratospheric aircraft the amplitude and spectrum of into the midlatitude lower strato- waves from each convective system Measurement Systems sphere, will probably exceed the using measurements, and extrapola- K. Roland Chan, T. Paul Bui, best current predictions by 30 to tion of these results to global budgets Antonio A. Trias, Stuart W. Bowen, 100%. These results may have using global satellite information. Jonathan Dean-Day important implications for the This task has progressed in two influence of stratospheric aircraft on areas. First, half-hourly datasets of The Meteorological Measure- the ozone layer. geostationary operational environment System (MMS) provides in situ, mental satellite (GOES-8) imagery high-resolution meteorological Point of Contact: M. Loewenstein for the strongly convective Panama parameters (pressure, temperature, (650) 604-5504 region have been prepared for and the three-dimensional wind [email protected] spectral analysis. The objective is to vector). The MMS consists of three use the satellite data to establish the major systems: (1) an air-motion frequency distribution at shorter sensing system to measure the spatial and time scales than that velocity of the air with respect to addressed by previous satellite the aircraft; (2) an aircraft-motion spectral studies. Second, two case sensing system to measure the studies of gravity waves generated velocity of the aircraft with respect by convection as observed by ER-2 to the Earth; and (3) a data acquisi- aircraft measurements have been tion system to sample, process, and

A TMOSPHERIC CHEMISTRY 159 record the measured quantities. making the temperature measure- collect scientific data in a timely and Since much of the instrumentation is ment independent of the aircraft cost-effective manner. The ERAST attached to the aircraft at specially attitude effects. sensor element addresses the science chosen locations, the MMS is a The DC-8 MMS is a new and payload aspects of RPA mis- platform-specific instrument that instrument, flight-tested for the first sions. Early focus centered on cannot be transported from one time in May 1996. The MMS instruments for high-altitude aircraft to another. performed very well during the (25␣ kilometers) atmospheric re- The MMS is uniquely qualified subsonic aircraft: contrail and cloud search. More recently, efforts have to investigate atmospheric mesoscale effects special study, which also supported a wider range of science (gravity waves) and microscale began its deployment mission in mission development activities, (turbulence) phenomena. Since the May. A preliminary set of MMS embracing a broader range of users. MMS provides quality data on products are measurements of static The present research is being atmospheric state variables, MMS pressure (p), temperature (T), the performed in collaboration with the data have been extensively used in east/west component of wind (u, National Oceanographic and almost all investigations to interpret with east being positive), the north/ Atmospheric Administration, other the in situ experiments aboard the south component of wind (v, with NASA Centers, the National Center same aircraft. north being positive), the vertical for Atmospheric Research, the U.S. Over the past decade, the ER-2 component of wind (w, with up Department of Energy Laboratories, MMS has successfully participated in being positive), latitude, longitude, several universities, and the Office of many missions, including the and pressure altitude. Analysis of the Naval Research. New concepts in Stratospheric Tracers Atmospheric three sets of temperature data (two RPA over the horizon (OTH) com- Transport missions in FY95 and sets from the Tslow probe and one set munications, key to extended FY96. from the Tfast probe) indicates that missions, are being developed and The MMS instrumentation has the self-consistency of the tempera- tested. Research in extremely been modified several times. Recent ture measurement is within miniaturized sensor technologies significant modifications to improve ±0.3 degree kelvin of the MMS holds promise for profound changes the system reliability include: design specifications. in the capability of RPAs. (1)␣ improved navigation data using The ERAST sensor element made Point of Contact: K. Chan the Litton LN-100G, a lightweight significant contributions to the (650) 604-6263 ring laser gyro embedded in the outreach in both the sensor and [email protected] Global Positioning System inertial platform communities in FY96. The reference system; (2) improved static sensor element sponsored three pressure measurement accuracy and retreats for sensor engineers during precision by using quartz diaphragm the year, which brought together a transducers, which have very low Environmental Research small group of experienced engi- thermal expansion coefficients; Aircraft and Sensor neers from ERAST instrument (3)␣ improved pitot pressure measure- development projects. ment, and hence true-air-speed Technology The ERAST sensor element measurement by customizing the Steve Wegener demonstrated a major milestone in pressure range calibration to the FY96: the ability to monitor and ER-2 flight envelope; and (4) a Environmental research aircraft command RPA payloads via a Rosemount open-wired, fast- and sensor technology (ERAST) satellite communications link. The temperature sensor installed forward provides focus for critical technology airborne data system and an infrared on the fuselage, well outside of development and flight demonstra- camera aboard the Scaled Compos- perturbed boundary layer flow, tion that reduces the technical and ites D2 RPA were monitored for economic risk of using remotely status, the communication package piloted aircraft (RPA) as a means to was reconfigured in flight, and the

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camera was commanded to acquire weight, volume, and power Global Emissions imagery and downlink data. This requirements. accomplishment demonstrates the The ERAST sensor element Inventories for Radon ability to monitor and command sponsored a review of current and the Cosmogenic platforms and payloads OTH, a atmospheric science instruments Radionuclides capability critical for operation at used in the Upper Atmosphere Mark Kritz distances greater than 160 kilome- Research Program. The intention ters from homebase. OTH communi- was to identify approaches where Natural radionuclide measure- cations supporting interactive micromachine concepts might lead ments are finding increasing applica- research platforms will enhance to significant breakthroughs required tion in the development and operational safety and scientific to shrink, in a revolutionary way, the validation of global circulation and productivity. weight, volume, and power con- chemical tracer models. In particu- The ERAST OTH communica- sumption of today’s payloads. The lar, comparisons of the atmospheric tion development effort provided the study (in technical review) con- radon distributions predicted by following OTH hardware capabili- cluded that, although some reduc- global models with radon measure- ties in FY96: tion was possible, reductions by a ments made at a surface station and ␣ ␣ •␣ ␣ The telemetry interface and data factor of ten required new measure- aboard NASA aircraft flying in the system was upgraded to be compat- ment concepts. New work in surface free troposphere have been used in ible with the Tracking and Data acoustic wave technology suggests two recent World Climate Research Relay Satellite System (TDRSS) that sensitivities comparable to Programme workshops, and by the interface electronics. Flight tests today’s instruments can be achieved Global Modeling Initiative compo- were conducted in December 1995 in shoe-box size packages. In nent of NASA’s Atmospheric Effects and September 1996. collaboration with NASA’s Mars of Aviation Program, to identify ␣ ␣ •␣ ␣ TDRSS Interface electronics. Pathfinder project, NASA’s Sensors shortcomings in the convective and ␣ ␣ •␣ ␣ An infrared imaging payload was 2000!, Sandia National Laboratories, long-range horizontal transport developed to demonstrate the OTH the University of California, Berke- parameterizations used in state-of- capability, build expertise for remote ley, and the Jet Propulsion Labora- the-art global atmospheric models. sensing science, and foster coopera- tory, the ERAST sensor element is However, as this work has continued tion with the Lawrence Livermore funding a laboratory study to and progressed and models have National Laboratory. demonstrate parts-per-billion continued to improve, there has ␣ ␣ •␣ ␣ System integration and testing measurement of carbon monoxide been a growing need to review and demonstrated the system capability (CO), nitrous oxide (N O), water 2 perhaps reassess current estimates of on NASA Lear jet and ERAST D2 vapor, and ozone with acoustic the source functions for these platforms. (surface acoustic wave and flexural radionuclides, including not only ␣ ␣ •␣ ␣ A systematic approach to plate) and chemiresistive technolo- that of radon (222Rn) but also requesting and obtaining approval gies. Demonstration of these results those of 7Be and other natural for use of radio frequency spectra in a modular sensor array instrument radionuclides. for TDRSS demonstration was is slated for FY97. To this end, the International established. Point of Contact: S. Wegener Global Atmospheric Chemistry ␣ ␣ •␣ ␣ A “roadmap” for OTH capability (650) 604-6278 (IGAC) Program has included a for the ACE 2 was established. [email protected] natural radionuclide element in its Extremely small sensor systems are Global Emission Inventories Activity key to placing meaningful payloads (GEIA). The natural radionuclide at very high altitudes. New panel, functioning under the GEIA/ approaches to sensor systems are IGAC umbrella, has participants being explored to reduce payload

A TMOSPHERIC CHEMISTRY 161 from France, Germany, Japan, New South America or Africa. However, region, by processes that involve Zealand, and the United States. until this work, the roles that each intense boundary layer mixing and Projects in FY96, performed in played and the process for mid- convective clouds reaching to the collaboration with Stephen Schery oceanic, midtropospheric pollution upper troposphere. The lower of the New Mexico Institute of were not clear. The work describes tropospheric mixing process is the Technology and Phil Rasch of the the origin and character of the main source of slow, westward National Center for Atmospheric Great African Plume from biomass moving pollution episodes that Research, included: (1) work on a burning. produce maxima in tropospheric global radon emissions map to A three-dimensional tropo- carbon monoxide and ozone just replace the 1atom/centimeter2/ spheric chemistry model that south of the Equator, and extend to second global mean value currently assimilates the winds and weather the western tip of South America. in widespread use, and (2) initiating that prevailed during NASA’s Thunderstorm mixing of pollutants (as a complement to direct onsite airborne expedition, the Tropical tends to lead to southeastward local point surface flux measure- Atmospheric Chemistry Experi- movement of these pollutants, and ments) a subproject to infer the ment—Atlantic, has been created. great pinwheeling plumes of carbon global mean radon source functions The model also helps to establish monoxide and ozone spin out from using long-term observed mean important quantitative details, such the central convective areas of Africa atmospheric distributions of radon as the amount of biomass-burning and especially South America, and the deposition at the surface of emission of carbon monoxide and particularly above 8 kilometers. The its decay product 210Pb. the ability of clouds to vent material model has successfully simulated to the upper troposphere. The latter aircraft observations in many details, Point of Contact: M. Kritz venting process creates the Upper and seems to explain more generally (650) 604-5493 South American Plumes and the the satellite observations of carbon [email protected] Upper African Plume, which pollute monoxide. virtually the entire southern Most ozone in the model hemisphere. simulations seems to be made close The maintenance of the concen- to the source, over the continent, The Great African Plume: trations of carbon monoxide and only a day or so downwind of the Tropical Carbon Monoxide tropospheric ozone are the results of agricultural burning that is its source. complex interplay of many natural Theory and models suggest that and Ozone Simulation and social phenomena that make up nitrogen oxides die out, and ozone Robert B. Chatfield tropical agriculture, followed by production must then cease. Obser- interactions of many chemical vation, however, has shown a Maintenance of high concentra- species and meteorological pro- remainder of chemically significant tions of pollutants, for example, cesses. This project has made concentrations of nitrogen oxides in tropospheric carbon monoxide and explicit several, while pointing out a the middle and upper troposphere. It ozone, in seemingly distant regions remaining anomaly in the theory that is, therefore, suggested that there is a of the tropical troposphere is the is now widely recognized. The most “re-NOx-ification” process that focus of this research. Each of these visible concentration of tropospheric reproduces photochemically active compounds has a major role in ozone in the mid-Atlantic appears to nitrogen oxides, NOx. controlling the oxidizing capacity of be caused by the Great African Point of Contact: R. Chatfield the lower atmosphere. It was thought Plume, which extends up to about (650) 604-5490 that the source of a particularly 6␣ kilometers. This plume arises out [email protected] striking accumulation of tropo- of a convergence of polluted mate- spheric ozone in the middle of the rial in Equatorial and Southern Equatorial Atlantic Ocean was due Africa. Pollution is then lofted in the to biomass burning taking place in interoceanic convergence of the

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Instrument for this tunable infrared diode laser atmosphere over the Pacific Ocean. system, high-frequency wavelength These experiments aim to elucidate Tropospheric Nitrogen modulation spectroscopy is mechanisms by which ozone in the Studies employed. Detection sensitivity for troposphere is formed, destroyed, James R. Podolske these two gases is expected to be in and transported. To achieve this aim, the one-to-ten parts per trillion by data from the PEM-B mission were An open path tunable infrared volume range. In FY96, tests of the extensively analyzed and a new set monitor of the atmosphere aircraft wing dynamics required to of field measurements involving (OPTIMA) instrument is being specify the alignment system were nitrogen, carbon, sulfur, and tracer developed to measure nitric acid completed. The preliminary design species were performed during a (HNO3) and nitrogen dioxide (NO2) of all the instrument subsystems was five-week PEM-Tropics deployment. from the NASA DC-8 aircraft. completed, and the final design Major deployment sites for PEM- Assessing the effect of the current reached the 50% level. Tropics were California, Fiji, Tahiti, fleet of commercial subsonic aircraft Easter Island, and New Zealand. Point of Contact: J. Podolske on the Earth’s atmosphere requires Highly sensitive measurements of (650) 604-4853 detailed knowledge of the nitrogen reactive nitrogen species, oxygen- [email protected] chemistry of the upper troposphere ated hydrocarbons, and chemical and lower stratosphere. To date, tracers were performed by the Ames understanding of this problem has group by deploying an instrument been hampered by large uncertain- called PANAK (PANs/aldehydes/ ties, both in the abundances of the Reactive Nitrogen and ketones). odd-nitrogen reservoir species and in Oxygenated Hydrocarbon Point of Contact: H. Singh the partitioning of reactive nitrogen (650) 604-6769 (NO ) between nitric oxide (NO) Measurements during the y [email protected] and NO2. Among the nitrogen Pacific Exploratory reservoir species, HNO3 is expected Mission to be one of the predominant Hanwant B. Singh, W. Viezee, compounds. Presently, numerical R. Chatfield, Y. Chen, D. Herlth, models of the upper trososphere and Subsonic Aircraft: Contrail R. Kolye lower-stratosphere region predict and Cloud Effects Special NO and NO partitioning which x y The Pacific troposphere is a differs greatly from that derived from Study major region of the northern hemi- existing measurements. Current Owen B. Toon, Steve Hipskind, sphere that is relatively free of direct instrumentation has been shown to Duane Allen, Paul Bui, Roland Chan, influences from man-made pollu- be inadequate for measuring HNO Mike Craig, Guy Ferry, Steve Gaines, 3 tion. Tremendous industrial growth and NO with the speed and accu- Warren Gore, Eric Jensen, Joe Jordan, 2 in Asia and North America in recent racy required to advance under- Stefan Kinne, Bill McKie, decades has the potential to signifi- standing in this area. Peter Pilewskie, Rudi Pueschel, cantly affect this pristine region. The OPTIMA instrument uses an Tony Strawa, Annette Walker The Pacific Exploratory Mission-B infrared laser spectrometer coupled (PEM-B) and -Tropics (PEM-Tropics), to an actively aligned multiple pass The subsonic aircraft: contrail performed in collaboration with Herriott sampling cavity whose open and cloud effects special study L. Salas of the San Jose State Founda- absorption path between the fuse- (SUCCESS) program was a NASA tion, are major contributors to the lage and the inner engine pylon field program that used scientifically NASA Global Troposphere Experi- achieves a free-stream absorption instrumented aircraft and ground- ment, designed to study the state of path length of 384 meters. To further based measurements to investigate the perturbed and the unperturbed enhance the detection sensitivity of the effects of subsonic aircraft on

A TMOSPHERIC CHEMISTRY 163 contrails, cirrus clouds, and atmo- from May 10 until May 15, 1996, at large suite of tracer observations spheric chemistry. SUCCESS had NASA’s Ames Research Center. provides stringent tests for under- several objectives. One was to better SUCCESS coordinated with the U.S. standing the processes that control determine the radiative properties of Department of Energy’s (DOE’s) ozone photochemistry. The STRAT cirrus clouds and contrails so that Atmospheric Radiation Measure- campaign has extended the regions satellite observations can more ments Program, which operates the and seasons for which such mea- reliably measure their effect on Cloud and Radiation Testbed (CART) surements have been taken. Earth’s radiation budget. Study site located in Northern Oklahoma. The experiment made atmo- questions included determining In addition to the extensive ground- spheric observations with an array how cirrus clouds form, whether based measurements at the CART of instruments on the NASA ER-2 the exhaust from subsonic aircraft site, DOE also operated an Egret and aircraft that measured long- and presently affects the formation of a Twin Otter aircraft, mostly using short-lived chemical tracers, meteo- cirrus clouds, and, if the exhaust remote-sensing instruments. rological parameters, radical species, does affect the clouds, whether the aerosol particles, and solar radiation. Point of Contact: S. Hipskind changes induced are of climatologi- The experiment consisted of six field (650) 604-5076 cal significance. Several new campaigns of approximately two to [email protected] instruments were also developed. three weeks each. The individual The study also helped to better campaigns consisted of local, determine the characteristics of midlatitude flights out of Ames gaseous and particulate exhaust Research Center and tropical flights products from subsonic aircraft and Stratospheric Tracers of to and from the island of Oahu, their evolution in the region near the Hawaii. Included in the February aircraft. Atmospheric Transport 1996 campaign was a coordinated To achieve these experimental Stephen Hipskind, Michael Craig flight with the NASA DC-8 aircraft objectives, the NASA DC-8 and T-39 during the Tropical Ozone Transport aircraft were used in situ as sampling The primary goal of the Strato- Experiment/Vortex Ozone Transport platforms; the NASA ER-2 aircraft spheric Tracers of Atmospheric Experiment mission. In the coordi- was deployed as a remote-sensing Transport (STRAT) program is the nated flight, the ER-2 made measure- platform; and the NASA 757 was measurement of the morphology of ments while flying in the exhaust used as a source aircraft for studies long-lived tracers and dynamical plume of the NASA DC-8 aircraft. of contrails and exhaust. quantities as functions of altitude, STRAT was sponsored by The experiment was cospon- latitude, and season in order to help NASA’s Atmospheric Effects of sored by NASA’s Subsonic Assess- determine rates for global-scale Aviation Project, Upper Atmosphere ment Program and the Radiation transport and future distributions of Research Program, and Atmospheric Sciences Program, which are part of high-speed civil transport (HSCT) Chemistry Modeling and Analysis the overall Aeronautics and Mission exhaust emitted into the lower Program. to Planet Earth programs, respec- stratosphere. The observations Approximately 100 participants tively. SUCCESS had well over a obtained will improve understanding from Ames, other NASA centers, hundred direct participants from of broader issues involving transport other government agencies, universi- several NASA Centers, other govern- of gases and aerosols in the ties, and private consulting compa- ment agencies, universities, and stratosphere. nies were involved in this research. private research companies. A secondary goal of STRAT is The ER-2 carried a complement of The SUCCESS project was the further characterization of 15 scientific instruments, making conducted from the Kansas State atmospheric photochemistry. As primarily in situ measurements with University airport facilities in Salina, shown in earlier airborne cam- two remote-sensing instruments. Kansas, from April 8, 1996, until paigns, measurement of free radicals Overall, 53 flights of the ER-2 used May 10, 1996, with an extension within the context of a sufficiently more than 260 hours of flight time.

164 A TMOSPHERIC CHEMISTRY M ISSION TO PLANET EARTH ENTERPRISE

STRAT has provided a rich the results of the closure studies to The combined surface, air, and dataset with seasonal coverage over assess and reduce uncertainties in space datasets obtained in TARFOX two years, vertical profiles from the estimates of aerosol radiative will permit a wide variety of closure upper troposphere to the lower forcing, as well as to guide future analyses. “Internal closure” will be stratosphere (33,000 to 70,000 feet), field programs on this subject. assessed by comparing the quantities and latitudinal coverage from An important component of the thus derived with those deduced approximately 2 degrees South to closure studies is tests and improve- from the simultaneous in situ more than 60 degrees North. The ments of algorithms that retrieve measurements of aerosol size analysis of these data will increase aerosol properties and effects from distribution and chemical composi- understanding of the transport and satellite and aircraft radiometers. The tion. “External column closure” will distribution of emissions into the resulting validated algorithms will be assessed by comparing aerosol lower stratosphere by future HSCTs. permit extensions of the TARFOX extinction computed from the in situ The data from the first three deploy- results to other times and locations measurements on the C-131A with ments has been published on that have aerosol properties similar those derived from the airborne CD-ROM. to those of the TARFOX Intensive sunphotometers, satellite radiom- Field Period (IFP). eters, and ER-2 imaging Point of Contact: S. Hipskind NASA Ames contributed to spectrometers. (650) 604-5076 TARFOX by supplying the Project Such closure analyses will yield [email protected] Scientist, Project Manager, an critically needed assessments and ER-2 aircraft, and two airborne should reduce the uncertainties in sunphotometers. The TARFOX IFP, derived values of anthropogenic including coordinated measurements aerosol radiative forcing. The closure Tropospheric Aerosol from four satellites (GOES-8, NOAA- analyses that use satellite optical Radiative Forcing 14, ERS-2, LANDSAT), four aircraft depth and flux results will provide (ER-2, C-130, C-131, and a modified tests and, where necessary, improve- Observational Experiment Cessna), land sites, and ships, was ments of satellite retrieval algo- Philip B. Russell, John M. Livingston, conducted July 10–31, 1996. A rithms. The resulting validated Wendy Whiting variety of aerosol conditions were algorithms will permit extensions of sampled, ranging from relatively the TARFOX results beyond the The overall goal of the Tropo- clean behind frontal passages to TARFOX period and to other loca- spheric Aerosol Radiative Forcing moderately polluted, with aerosol tions dominated by similar aerosols Observational Experiment (TARFOX) optical depths exceeding 0.5 at (for example, the European Atlantic is to reduce uncertainties in the midvisible wavelengths. The latter coast). effects of aerosols on climate by conditions included separate Point of Contact: P. Russell determining the direct radiative incidents of enhancements caused (650) 604-5404 effects, as well as the chemical, primarily by anthropogenic sources [email protected] physical, and optical properties of and another incident of enhance- the aerosols carried over the western ment apparently influenced by Atlantic Ocean from the United recent fog processing. Spatial States. Other objectives of TARFOX gradients of aerosol optical thickness are (1) to perform a variety of closure were sampled to aid in isolating studies by using overdetermined aerosol effects from other radiative datasets to test the mutual consis- effects and to more tightly constrain tency of measurements and calcula- closure tests, including those of tions of a wide range of aerosol satellite retrievals. properties and effects; and (2) to use

A TMOSPHERIC CHEMISTRY 165 Atmospheric ATMOSPHERIC PPhysicsHYSICS Relating the H2SO4 emission may be sufficiently significant to be indices to the fuel-S (sulfur) content included in models. resulted in the sulfur gas-to-H SO 2 4 Point of Contact: R. Pueschel Fine Particle Emissions particle conversion of between (650) 604-5254 by Aircraft 9␣ and 24%. This result is close but [email protected] Rudolf F. Pueschel, Guy V. Ferry, outside the range of 3 to 12% of Anthony W. Strawa, Duane Allen sulfur oxidation that could be attributed to hydroxyl radical (OH)- Collections of aerosols were limited gas-to-particle conversion. made with the Ames wire impactors Thus, a mechanism of H2SO4 FIRE Phase III aboard the NASA DC-8 aircraft generation in aircraft exhaust that Peter Pilewskie, Warren Gore flying in the exhaust of a Boeing 757 has yet to be determined appears to aircraft during the subsonic aircraft: exist. Begun in 1986, the First Interna- contrail and cloud effects special The 1990 fuel use by the tional Satellite Cloud Climatology study mission. Morphological commercial airline fleet amounted Project Regional Experiment (FIRE) analysis of scanning electron to 1.3E11 kilograms. If the fuel-S has been an ongoing multiagency micrograph (SEM) images and content averaged 500 parts per program designed to promote the energy-dispersive analysis of x-rays million mass, a conversion efficiency development of improved cloud and emitted during exposure of the of 20% would have led to a contri- radiation parameterizations for use particles to electrons in the SEM bution by aircraft of 1.3E7 kilograms in climate models, and to provide for allowed a distinction between of H2SO4, or approximately one part assessment and improvement of in 1.E4 of anthropogenic sulfate ion sulfuric acid (H2SO4) and soot International Satellite Cloud Clima- aerosols. Size classification and (SO4) from other sources. If an tology Project products. The strategy integration over size distributions average Eisoot = 7.5E-4 grams per of FIRE has been to combine model- of both types of aerosols yielded kilograms of fuel is assumed, the ing activities with satellite, airborne, ambient concentrations, particle annual emission of soot into the and surface observations. surface, particle volume, and atmosphere in 1990 would have The third phase of FIRE, or FIRE particle effective radii. This research amounted to 1.E5 kilograms. Com- III, has begun with renewed efforts to was performed in collaboration with pared with 24␣ teragrams of total understand the physical and dynami- Jindra Goodman of San Jose State anthropogenic soot emission, it cal properties of climatically impor- University, Steve Howard of follows that aircraft contributions tant cloud systems, cirrus, and Symtech, Sunita Verma of TMA/ would have amounted to one part in stratiform clouds. Project personnel Norcal, and Glenn Sachse of the 1.E5 parts of total soot aerosol. completed the second year’s work NASA Langley Research Center. Thus, aircraft appear to be only developing new solar spectral The ambient carbon dioxide a minor source for both H2SO4 and radiometric instrumentation for soot aerosol. Nevertheless, the (CO2) concentrations, determined cloud remote sensing and atmo- at NASA Langley Research Center, measurements reported highlight the spheric radiative flux measurements. were 1.E-4 to 1.E-5 times the issue of particulate (soot and sul- In FY96, progress was made toward concentrations emitted at the engine fates) emissions from aircraft. The FIRE III goals by testing a prototype exhaust plane. Applying these potential for the aircraft emissions of solar spectral flux radiometer (SSFR) dilution factors to the soot and water vapor (H2O), sulfur (S), and at a ground site during the NASA particulates to change the nitrogen H2SO4 aerosols yielded emission subsonic aircraft: contrail and cloud oxides (NOx) effectiveness to indices between 0.05 < EIH2SO4 < effects special study mission. Aside 0.5 grams per kilogram of fuel and atmospheric ozone (O3) changes from providing important informa- 2.5E-4 < Eisoot < 1.4E-3 grams per tion on the solar radiative properties kilogram of fuel, respectively. and effects of cirrus and cirrus

166 A TMOSPHERIC PHYSICS M ISSION TO PLANET EARTH ENTERPRISE

contrails, the benefit of the surface bands that are relevant for planetary 6584.3 angstroms is a relatively deployment was the expedition of spectra in the NASA-Ames High isolated methane line. the development of the airborne Resolution Spectroscopy Laboratory. Point of Contact: L. Giver SSFR, which will be flown in 1997. In collaboration with D. C. (650) 604-5231 The team will have airborne and Benner of the College of William [email protected] surface capabilities to determine the and Mary and NASA Langley net solar spectral flux at multiple Research Center, and L. R. Brown levels in the atmosphere, and can and J. S. Margolis of the NASA Jet therefore determine the spectral Propulsion Laboratory, recent work absorption characteristics of the has emphasized intensity measure- Near-Infrared Remote clear and cloudy atmosphere. ments of very weak near-infrared Sensing of Cloud Liquid Uncertainties in the amount of solar carbon dioxide (CO2) bands that are radiation absorbed by water vapor important for understanding the Water and clouds continue to be a major spectrum of the night side of Venus, Peter Pilewskie, Warren Gore focus in atmospheric radiative and which has a massive CO2 atmo- climate studies. sphere. The first intensity measure- The 1995 Arizona Program was ments of several of these bands were a multiinvestigator field experiment Point of Contact: P. Pilewskie made using spectra obtained at aimed at advancing the understand- (650) 604-0746 Ames; an article reporting these ing of winter storm development, [email protected] measurements of bands in the morphology, and precipitation in a 7000-per-centimeter region was mountainous region of central published in the Journal of Molecu- Arizona. From January 15 through lar Spectroscopy. Also, measure- March 15, 1995, a wide range of Laboratory Spectroscopy ments of the perpendicular band at instrumentation was in operation of Carbon Dioxide in 5315 per centimeter were reported in and around the Verde Valley at the Seventh Annual Conference southwest of Flagstaff, Arizona, Support of Planetary on Laboratory Research for Planetary including the Ames visible and near- Atmospheres Research Atmospheres in Kona, Hawaii, in infrared spectroradiometers, two Doppler radars, an instrumented Lawrence P. Giver, October 1995. Collaboration Charles Chackerian, Jr. between Ames and the NASA aircraft, a lidar, microwave radiom- Langley spectroscopy group resulted eters, and other surface-based Spectra of planets have absorp- in a careful comparison of intensity instrumentation focused on the tion bands caused by the molecules measurements of the band at analysis of wintertime storms in this in their atmospheres. Measurements 4006 per centimeter; these results geographically diverse area. Over of these spectral features can yield were presented at the Fifty-first Ohio 25␣ scientists from seven institutions information about these planetary State Symposium on Molecular took part in the program. atmospheres, such as the abundance Spectroscopy in June 1996. Of special interest to the Ari- of the absorbing molecules and the As an extension of prior work zona Program is the interaction of pressure and temperature of the gas. on the visible spectrum of methane topographically induced gravity Measurement requires knowledge of (CH4), which is abundant in the waves with the ambient upslope absorption band absolute intensities, atmospheres of all the outer planets, flow. It is hypothesized that these line positions, pressure broadening two spectra obtained at the Kitt Peak waves may augment the upslope- parameters, and temperature depen- Observatory have shown that a forced precipitation that falls dencies. Over the past 30 years, previously unidentified absorption downwind of this feature onto the measurements of these parameters line in Saturn’s spectrum at Mogollon Rim. A major thrust of have been made on absorption the program is to compare the

A TMOSPHERIC PHYSICS 167 observations of these, and other analysis, based on photon path intensity values needed to establish aspects of winter storms, with those length distribution calculations, will limits of detectability for as-yet- predicted with a numerical model. be necessary to obtain liquid water unobserved species and quantify the The primary role of this research and water vapor in absolute units. abundance of those species that are effort was to provide cloud remote- Nevertheless, the work completed observed; (2) line positions, half sensing analysis for determining during the two years of this project widths, and pressure-induced shifts, cloud water thermodynamic phase, went far in developing this new which are all needed for remote and cloud thickness, and liquid water remote-sensing technique, and will in situ sensing techniques; and content (LWC). The unique collec- continue in the First International (3)␣ data on the basic molecular tion of surface and in situ sensors Satellite Cloud Climatology Project parameters at temperatures and provided valuable data toward future Regional Experiment. Furthermore, pressures appropriate to the real efforts in determining the relation- the instrument developed for this atmosphere. ships between cloud radiative study, and the data acquired during Previously, oxygen (O2) pressure properties and microphysics and two major field campaigns, were broadened spectra of the nitric oxide investigations into the role of clouds applied to other current problems in (NO) vibration-rotation fundamental in climate. Understanding the role of solar radiative transfer, namely, the were obtained using a flow system. clouds in climate is predicated not amount of radiation absorbed in These are the first such data to be only on determination of the com- clouds, and the amount of radiation recorded. These spectra will be plex manner in which radiative absorbed in the cloud-free analyzed for O2 broadening coeffi- energy is redistributed by clouds but atmosphere. cients for use in interpreting atmo- also on the hydrological processes spheric retrievals of NO abundance. Point of Contact: P. Pilewskie that regulate the distribution of High-quality 0.005-per-centimeter (650) 604-0746 condensed water and water vapor in resolution spectra of nitric acid [email protected] the atmosphere. There are funda- (HNO3) were obtained in the mental gaps in the present under- 1100- to 2700-per-centimeter standing of the hydrological cycle spectral region. Rovibrational line that limit the ability to assess the intensities on these spectra will be present climate, let alone predict Quantitative Infrared determined to support the Open future climate, or climate response Spectroscopy of Minor Path Trace Species Measurements in in the presence of increased green- Constituents of the Earth’s the Atmosphere experiment. Analy- house gases. Because the removal sis for the electric dipole moment rate of condensed water depends Atmosphere function of the ground electronic strongly on cloud LWC, determining Charles Chackerian, Jr., state of the hydroxyl radical (OH) the distribution of LWC and its Lawrence P. Giver molecule was completed using a dependence on temperature are very large set of relative emission crucial toward a better understand- The objectives of this study are lines of the Meinel system. A ing of cloud-climate feedback. to obtain quantitative laboratory definitive and comprehensive Analysis of the Arizona Program spectroscopic measurements of compilation of rovibrational intensi- data continued in FY96. A new molecular constituents, which are of ties for the carbon monoxide (CO) method of analyzing surface-base importance in understanding the molecule in its various isotopic cloud transmission spectra, devel- “health” of the Earth’s atmosphere, forms was published. oped during the first year of this and, in particular, emphasize those An experimental feasibility study project, was useful in deriving both species that are important for was completed for using magnetic cloud liquid water as well as water understanding stratospheric kinetics rotation spectroscopy (MRS) to vapor. Presently, the retrieval or are used for long-term monitoring detect free radical molecular species method derives the relative propor- of the stratosphere. These measure- (in situ) in the part-per-trillion mixing tions of those quantities. New ments provide: (1) line and band ratio range. A quantitative theory

168 A TMOSPHERIC PHYSICS M ISSION TO PLANET EARTH ENTERPRISE

was developed to analyze the MRS and on the role they play in atmo- nuclear bomb testing was terminated results obtained as well as to predict spheric photochemical, dynamical, in the early 1960s, the 14C data instrumental parameters required for and radiative processes. Transport permit estimates of interhemispheric parts per trillion by volume detection plays a role in this scheme, because mixing times that turn out to be of free radical molecular species. A the background concentrations of longer than stratospheric residence multipass reflection cell inside a atmospheric constituents vary in times by more than one order of solenoid magnet has been con- space. For example, effects on magnitude. This scenario explains a structed to achieve parts-per-trillion- column ozone of aircraft-emitted decade-long confinement of aircraft by-volume sensitivity. nitrogen oxides (NOx) result from soot to the hemisphere into which it Infrared spectra were obtained decreases in the middle and upper has been emitted. using an interferometer and a stratosphere and increases in the Although there is agreement 25-meter base-path multiple reflec- lower stratosphere and troposphere. between the soot and 14C datasets in tion cell, in the 1.8-micrometer The balance between these increases horizontal interhemispheric mixing, region of the infrared red spectrum and decreases depends on the vertical mixing between the soot of nitric oxide for the purpose of dispersion of the aircraft effluent by aerosol emission level (12 kilome- designing a lidar-based smoke-stack atmospheric transport processes, as ters) and the NASA ER-2 aircraft detector for this molecule. well as the transport of long-lived ceiling (20 kilometers) is indicated Experiments have been per- species, including ozone, in the only in the soot measurements. formed to measure line intensities of background atmosphere. Thus, one Transport from midlatitudes to the gaseous water in the 1-micrometer important aspect is that fraction of tropics, with subsequent lofting and spectral region to help in under- exhaust NOx that would be trans- transport back to midlatitudes at standing the apparent anomaly ported from the heavily traveled higher altitudes, is a possibility for associated with absorption of solar flight corridors in the lower strato- vertical mixing. However, since 14C radiation by clouds in the Earth’s sphere in northern midlatitudes to in the northern hemisphere does not atmosphere. the tropics, where it can be lofted to substantiate the soot results, vertical Collaborators in this research higher altitudes by atmospheric motion due to radiometric forces of include Chris Mahon of the Space circulation. Subsequent transport higher absorbing soot particles that Physics Research Institute, back to midlatitudes would be at could prolong their stratospheric P. Varanasi of the State University altitudes where the NOx from the residence times is a more plausible of New York, and D. Cooper of the exhaust dominates ozone depletion. explanation. Stanford Research Institute. Of interest also is the fraction of This research was performed in exhaust that could be transported collaboration with Jindra Goodman Point of Contact: C. Chackerian from the flight corridors in the of San Jose State University, Steve (650) 604-6300 northern hemisphere across the Howard of Symtech, and Sunita [email protected] equator to southern latitudes. Verma of TMA/Norcal. Transport of exhaust from north to Point of Contact: R. Pueschel south would reduce the concentra- (650) 604-5254 tion of this fraction and mitigate the [email protected] Stratospheric Transport effects in the northern hemisphere. Rudolf F. Pueschel, Guy V. Ferry, Soot aerosol measurements were Anthony W. Strawa, Duane Allen taken using the Ames wire impactor samples to document barriers to The atmospheric impact of interhemispheric mixing, analogous emissions by aircraft depends on to the stratospheric dispersion of how they change the steady-state radioactive 14C tracers after the abundance of constituents over nuclear bomb tests in the 1950s and background atmospheric amounts, early 1960s. Because atmospheric

A TMOSPHERIC PHYSICS 169 SUCCESS Irradiance A key component of the SUCCESS objectives was to obtain a better Measurements understanding of the spectral Peter Pilewskie, Warren Gore distribution of solar irradiance reaching the surface. First results A solar spectral flux radiometer from analysis of SSFR data suggest (SSFR) was deployed at the U.S. that absorption by water vapor can Department of Energy Southern be determined quite accurately, and Great Plains Cloud and Radiation the measured spectra agree with Testbed during April 1996 as part of model calculations within measure- the NASA subsonic aircraft: contrail ment uncertainties. These findings and cloud effects special study will help eliminate long-standing (SUCCESS). The SSFR was used to discrepancies between theory and measure downwelling solar observation and, likewise, are spectral irradiance in the 250- to crucial to determining the effects of 2500-nanometer solar spectral contrails on the solar energy budget. region, with 10- to 15-nanometer resolution. From April 12 through Point of Contact: P. Pilewskie April 29, approximately (650) 604-0746 18,000 spectra were acquired, [email protected] under a variety of meteorological conditions; a significant portion of the spectra was favorable to the study of cirrus clouds and cirrus contrails. Analysis of the solar spectral flux dataset will facilitate the study of the effects of subsonic aircraft on the surface and lower atmosphere energy budget. Simulta- neous in situ observations by the NASA DC-8 will provide the micro- physical ground truth for assessment of the results. To determine radiative properties of cirrus and cirrus contrails and their net effects on radiative energy budgets, a proper understanding of the solar radiation spectrum in the cloud-free atmosphere is needed.

170 A TMOSPHERIC PHYSICS Appendix

The color plates in this appendix correspond to figure citations that appear in the text. Each caption also provides the location of the figure citation.

Color Plate 1. Air-traffic controllers at the Dallas/Fort Worth TRACON using FAST advisories to control arrival traffic. (Davis, p. 11)

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Ð.5 Area

Ð1

Ð1.5 0

.4 1 .8 .6 .6 .8 .4 .2 TE 1 LE 0

Color Plate 2. F-15 ACTIVE superimposed on aerodynamic flight envelope. (Jorgensen, p. 19)

173 Color Plate 3. Full Apache AH-64D airframe aerodynamic loading in forward flight. (Duque, p. 36)

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Color Plate 4. Vertical velocity contours and flow- Color Plate 5. Vertical velocity contours and flow- field streamlines, 0-degree angle of incidence. field streamlines, 15-degree angle of incidence. (Stremel, p. 36) (Stremel, p. 36)

175 Color Plate 6. Vortex cores (red) extracted from a simulation of a helicopter rotor in forward flight. (Kenwright, p. 39)

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Color Plate 7. Interactive placement and visualization of streaklines in the Virtual Windtunnel permits flow features to be easily found. (Kenwright, p. 42)

177 Color Plate 8. PDV measurements of axial velocity and its root-mean-square fluctuation amplitudes in a plane normal to the centerline of a low-speed, turbulent jet; the view in each image is upstream along the jet centerline. (McKenzie, p. 44)

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Color Plate 9. The exVis ImageViewer window (left) shows pressure-sensitive paint data for the OAW-3 oblique all-wing model. The white line segments are slice tools that have been interactively placed on the image. The GraphViewer (right) shows x-y plots of the coefficient of pressure versus length along the tool for each selection. The highlighted peak (the red marker on the green graph) was selected in the GraphViewer, resulting in showing the black spot along the gray tool where this value occurs. The third window (top right) is the simple user interface used to access datafiles and create ImageViewers and GraphViewers. (Uselton, p. 48)

Color Plate 10. Noise-level contours measured on 4.7%- scale DC-10 semi-span model in the Ames 12-Foot Pressure Wind Tunnel with 52-element Boeing phased microphone array. (Horne, p. 56) 179 Color Plate 11. Surface pressure contours for multiple design variable study: (a) original wing; (b) modified wing with four design variables; (c) modified wing with five design variables. (Greenman, p. 58)

Color Plate 12. Final mesh and computed pressure contours in the rotor plane. (Biswas, p. 59)

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Color Plate 13. Four different types of grids used in computational fluid dynamics. Clockwise from upper left: multiple overlapping zone structured grid for the V-22 tiltrotor aircraft; periodic multizone structured grid for turbomachinery; hybrid structured and unstructured grid for a helicopter rotor; unstructured tetrahedral grid for the Langley fighter. (Bryson, p. 61)

181 Color Plate 14. Optimized HSR configuration. (Cliff, p. 67)

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Color Plate 15. Thin cirrus clouds scattered the light of the stars in this rare color photograph of the trail of an alpha-Monocerotid passing the star Sirius, captured by the Dutch Meteor Society observer Robert Haas at the Alcudia-de-Guadix location in Spain during the meteor outburst of November 22, 1995. (Jenniskens, p.␣ 81)

183 1st salvo 2nd salvo 3rd salvo

Each salvo consists of 50 8 stations

0 Latitude (degrees)

25 20 15 Ð50 10 5

0 Elevation (km) Ð5 Ð180 Ð140 Ð100 Ð60 Ð20 20 60 100 140 180 Longitude (degrees)

Color Plate 16. An illustration of possible network of 24 PASCAL stations on Mars. This network is achievable using centrifugal release from a spin-stabilized carrier spacecraft and two propulsive time-of-arrival adjustments. Three groups of eight stations each follow three sinusoidal loci and are marked by black circles (1st salvo), red squares (2nd salvo), and blue diamonds (3rd salvo). Topography is shown in color contours. (Haberle, p. 88)

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Color Plate 17. The disk, showing a Color Plate 18. Strong, non- pronounced annular gap at the halo/ axisymmetric structure is evident in epicycle frequency resonance. This the disk at late times in the pattern persists for the entire length of experiment. This bar is absent when the experiment, which is on the order the halo remains static. Such offset of a Hubble time. (Smith, p.␣ 91) bars are often seen at the centers of disk galaxies. (Smith, p. 91)

Meteorological Data for the Summer (JJA) Season

40 North latitude (degrees) 30

0 180 160 140 120 10080 60 180 160 140 120 10080 60 40 West longitude (degrees)

0 24681012161814 20 Contour values Color Plate 19. (a) The SAGE II frequency of cloud occurrence from 0 to 100% in 5% increments. (b) The HIRS frequency of cloud occurrence from 0 to 30% in 1.5% increments. (c) The average tropopause height from 27,000 to 67,000 feet in increments of 2,000 feet. (d) The MLS-derived water vapor overburden from 4 to 24 precipitable microns in increments of 1 micron. (Haas, p. 95) 185 Color Plate 20. The image of the skull of the female from the Visible Human dataset is visualized on the screen of the Immersive WorkBench. Rei Cheng (left) and Muriel Ross are studying the 3-D reconstruction with the aid of special glasses. Rei Cheng is demonstrating special gloves that will be used to manipulate instruments and pieces of bone or other tissue in the immersive environment. (Ross, p. 119)

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Ð30

Ð60 a) N2O

Ð90

90 Latitude (degrees)

Ð30

Ð60 b) NO

Ð90 Ð180 Ð150 Ð120 Ð90 60 30 0 30 60 90 120 150 180 Longitude (degrees)

0 50 100 150 200 250 > 300 mg N mÐ2yrÐ1

Color Plate 21. Global patterns of annual (a) N2O and (b) NO emissions from soils. (Potter, p. 149)

187 SWHC .25

.20 a)

Scale: Kilometers .15 100 0 100 200

.10

.05

Color Plate 22. Top map: Conventional map of soil water holding capacity (SWHC) using homogeneous polygons. Bottom map: Map of SWHC developed in this research. (Coughlan, p. 152)

188 Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED September 1997 Technical Memorandum 4. TITLE AND SUBTITLE 5. FUNDING NUMBERS Research and Technology 1996

6. AUTHOR(S) Ames Investigators

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION REPORT NUMBER Ames Research Center Moffett Field, CA 94035-1000 A-976441

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY REPORT NUMBER National Aeronautics and Space Administration NASA TM-112195 Washington, DC 20546-0001

11. SUPPLEMENTARY NOTES Point of Contact: John T. Howe, Chief Scientist, Ames Research Center, MS 200-16, Moffett Field, CA 94035-1000 (650) 604-5500 or contact person(s) at the end of each article

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Unclassified — Unlimited Subject Category 99

13. ABSTRACT (Maximum 200 words) This report highlights the challenging work accomplished during fiscal year 1996 by Ames research scientists, engineers, and technologists. It discusses research and technologies that enable the Information Age, that expand the frontiers of knowledge for aeronautics and space, and that help to maintain U. S. leadership in aeronautics and space research and technology development. The accomplishments span the range of goals of NASA’s four Strategic Enterprises: Aeronautics and Space Transportation Technology, Space Science, Human Exploration and Development of Space, and Mission to Planet Earth.

The primary purpose of this report is to communicate knowledge—to inform our stakeholders, customers, and partners, and the people of the United States about the scope and diversity of Ames’ mission, the nature of Ames’ research and technology activities, and the stimulating challenges ahead. The accomplishments cited illustrate the contributions that Ames is making to improve the quality of life for our citizens and the economic position of the United States in the world marketplace.

14. SUBJECT TERMS 15. NUMBER OF PAGES Aeronautics, Space transportation, Space sciences, Earth sciences, Life sciences, 201 Information technology, Research and technology 16. PRICE CODE A09 17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT OF REPORT OF THIS PAGE OF ABSTRACT Unclassified Unclassified NSN 7540-01-280-5500 Standard Form 298 (Rev. 2-89) Prescribed by ANSI Std. Z39-18 298-102