Nasa Engineering & Safety Center

National Aeronautics and Space Administration

NASA ENGINEERING & SAFETY CENTER

2008 TECHNICAL UPDATE

www.nasa.gov 1 It gives me a lot of pleasure to recognize the 5th anniversary of the establishment of the NASA Engineering and Safety Center. It also offers, for me, a valuable reminder that it is important always to be open to new ideas and new approaches to solving problems. When the NESC was established, I was more than a bit pessimistic that it could work, that it could provide value for the Agency over and above that offered by our various center engineering directorates. I was wrong. The synergy that has been achieved by the NESC and its cross-agency approach to solving difficult technical problems has been truly impressive. It is, in my mind, a useful model for future endeavors and a great example that it is actually possible for us to “be NASA”, to rise above some of the parochial geographic concerns which have plagued NASA for five decades. These days, when someone tells me that the NESC is looking at a particular issue, I am reassured, because I know that if a solution can be found, this group will find it.

– Dr. Michael D. Griffin, NASA Administrator

2 Table of Contents Stakeholder Messages ...... 2 NESC Leadership ...... 3 Overview: How the NESC Works ...... 4 NESC Academy: Learning from the Past ...... 8 Technical Highlights Collecting Flight Force Measurements to Improve Coupled Loads Analysis .... 11 Analysis of Constellation Program Mass Properties ...... 11 Prediction and Reduction of Ares SRB Thrust Oscillation ...... 12 Review of the Launch Abort System Motor Qualification Plan ...... 13 Ares I-X Upper Stage Simulator Project Independent Structural Review ...... 13 Max Launch Abort System Risk Mitigation Project ...... 14 Updating of Launch Vehicle Shell Buckling Knockdown Factors ...... 17 Composite Crew Module Pressure Vessel Pathfinder Development ...... 18 Improved Crew Seat Attenuation Designs for the Orion Crew Module ...... 20 Improving Orion Crew Impact Tolerance Modeling ...... 21 Hypervelocity Particle Impact Resistance of JWST Electrical Cables ...... 23 Risk Assessment of Kepler Reaction Wheel Premature Failure ...... 24 RTAX Risk Mitigation Testing ...... 25 Entry, Descent, and Landing Data Repository and Analyses Task ...... 25 Development of DC/DC Converter Application Guidelines ...... 26 HYTHIRM Validation and Calibration Testing Demonstration ...... 27 NESC Data Mining and Trending Working Group (DMTWG) ...... 27 Probabilistic Requirements Verification ...... 28 Flight Battery Working Group Update ...... 28 Investigation of ISS Solar Alpha Rotary Joint Issue ...... 29 Determination of EMU Space Suit Glove Damage Modes ...... 29 Reproduction of ISS Solar Array Mast Shadowing ...... 30 Center Focus: Ames Research Center ...... 33 Dryden Flight Research Center ...... 34 Glenn Research Center ...... 35 Goddard Space Flight Center ...... 36 Jet Propulsion Laboratory ...... 37 Johnson Space Center ...... 38 Kennedy Space Center ...... 39 Langley Research Center ...... 40 Marshall Space Flight Center ...... 41 Stennis Space Center ...... 42 White Sands Test Facility ...... 43 Featured Technical Paper ...... 44-59 Biographies ...... 61-64 NESC Alumni ...... 65 NESC Honor Awards ...... 66-67 Recent NESC Publications ...... 68

Cover images clockwise from upper left - International Space Station solar array anomaly resolution, Composite Overwrapped Pressure Vessel testing, Orion Composite Crew Module construction pathfinder and Max Launch Abort System forward fairing wind tunnel testing. 3 Stakeholder Messages

The NASA Engineering and Safety Center (NESC) is now 5 years old and more vibrant and influential than ever. It is time to reflect a bit on how the NESC has evolved to become the success it has; clearly it has achieved its primary goal to engage the best personnel in NASA and from the outside to address our most difficult problems. However, over the last 5 years it has become more; it serves to train our workforce through the NESC Academy, it provides the technical leaders through the NASA Technical Fellows who provide leadership for their discipline. The NESC provides common tools to remove misunderstanding, and develop new tools as it has with the Max Launch Abort System and the Composite Crew Module. By all measures of organizational success the NESC and its people have excelled — so we all look forward to the next 5 years as the NESC and NASA pioneer this ‘New Ocean.’ Christopher Scolese NASA Associate Administrator

From its inception, the NESC’s core tenet has been to assemble the best possible technical expertise to apply to NASA’s toughest and most important problems. For tasks large and small, the NESC has demonstrated its agility and reach by quickly assembling the needed talent, whatever the source, and quickly bringing it to bear on a wide range of challenges. In the past year, the NESC has added to its strong record and continues to be the “go to” resource for NASA Programs and Projects. A few examples include expanding NASA’s technical experience with composites via the Composite Crew Module work for Constellation, increasing our depth of knowledge on the Reinforced Carbon-Carbon Orbiter wing leading edges, providing micrometeorite and orbital debris design input for the James Webb Space Telescope or characterizing solar array mass buckling behavior for the International Space Station. Perhaps the highest accolade is that it has become difficult to imagine what NASA would do if we did not have the NESC! On behalf of many, I offer my thanks and congratulations to the whole team for another year of excellent work. Michael Ryschkewitsch NASA Chief Engineer

The NESC has continued to serve the Agency over the past year as “the” technical organization of choice for our toughest engineering problems. They have developed over time an exceptional ability to expeditiously place the best people from both inside and outside of the Agency on the team. Of special importance to me this past year has been the discipline they have put into their technical reports. When an NESC assessment team reports their results, they take the time and effort to write them in a format that clearly states the problem, the scope and method of the assessment, and a clear English discussion of the results, findings and recommendations. And, they show the data. In an organization like NASA, this should not have been a big deal. But, over time, our hurry-up PowerPoint culture had led us to tolerate incomplete technical reporting almost as a standard. Old mishap lessons learned are replete with communications failures, so I applaud the NESC for reminding us all of the important contribution of clear communications to safety and technical excellence. Bryan O’Connor NASA Chief Safety and Mission Assurance Officer

4 NESC Leadership

From left: Ralph Roe, Jr., Dawn Schaible, Tim Wilson, Kenneth Cameron, and Patricia Dunnington

his year marks NASA’s 50th anniversary and the 5th year that the NASA Engineer- ing and Safety Center (NESC) has provided the Agency with the value-added independent assessments, testing and analyses it needs to address its highest-risk issues. The NESC’s operating model reaches across the Agency, industry, other T government agencies and academia to create diverse technical teams, and this inclusive outreach continues to be our true strength. Our broad-based, multi-disciplinary teams have provided NASA with a unique resource, and we are pleased to feature members of these teams throughout this year’s Technical Update. The NESC has used the broad-based team approach on two major efforts this year that are increasing the Agency’s understanding and capabilities for designing and building future spacecraft. Both the Composite Crew Module and Max Launch Abort System teams are featured in this publication. In addition to the numerous activities on behalf of the Constellation Program, the NESC continued to actively engage in the Space Shuttle and International Space Station Programs – including the Shuttle launch pad flame trench damage and ISS solar array buckling anomaly resolutions. The NESC has also maintained a focus on the Agency’s critical science missions, such as Kepler and Phoenix. This publication will also feature the NESC’s efforts to advance the state of the disciplines for many of our NASA Technical Fellows. Over the past five years, the NESC has demonstrated the value and power of broad-based, diverse teams. While our team members have changed, with many of our alumni going on to key leadership positions in the Agency, we have remained true to our core mission: providing NASA with a strong, independent resource to solve its toughest technical problems. We strive to remain current, relevant, and responsive to our customers and stakeholders. We have actively shared the lessons and results of our activities across the Agency through various avenues, including this publication. We are very proud to highlight our accomplishments and team members in this year’s Technical Update.

5 NESC Overview

How the NESC works

ASA’s mission is to pioneer the Center leadership, to provide an alternate future in space exploration, scientific reporting path through which problems can Ndiscovery and aeronautical research. be addressed. The NESC also works closely Achieving this requires unique technologies with the NASA Office of Safety and Mission that inevitably give rise to problems that Assurance and the NASA Safety Center. require unique solutions. Imagine if the The NESC is divided into the people working on those problems could following six offices: easily call on the entire Agency — not just colleagues within their program or their Center 1. NASA Technical Fellows — to help with the most difficult problems. They would have available a pool of 18,000 The NASA Technical Fellows are the Agency’s talented people from across the country from senior technical experts in 13 engineering which to draw. Take that proposition one disciplines (see inset). Each Technical Fellow step further – beyond the confines of NASA leads a technical discipline team (TDT) made to the engineering and scientific community up of experts from across the country – both as a whole – and the pool of available talent inside and outside of NASA. They provide would increase significantly. a pool of discipline-specific expertise from Current NASA Technical which to draw when assessment teams are Now further imagine a small organization Fellow Disciplines formed. within NASA, not reporting to any one • Aerosciences Center or specific program, but a resource NASA Technical Fellows act as stewards for • Avionics for the entire Agency. Fill this organization their disciplines by sponsoring workshops, • Flight Mechanics with the leading authorities in 13 different conferences, and discipline-advancing • Guidance, Navigation engineering disciplines. Give the authorities and Control activities. They also work to maintain the resources to form standing teams of • Human Factors consistency in Agency-level standards and experts in their disciplines from across NASA, • Life Support/Active incorporate lessons-learned into NASA’s Thermal industry, academia, and the government. engineering processes. Periodically, each • Loads and Dynamics Add an engineering representative for each Technical Fellow will present a “state-of-the- • Materials Center, and a group of engineers dedicated discipline” to the Agency’s senior leadership • Mechanical Systems to leading multi-discipline teams in solving to enhance awareness of specific concerns • Nondestructive technical problems. Finally, solidify the within the discipline. Some of these concerns Evaluation organization with strong systems engineering are pursued with resources provided by the • Propulsion and a resourceful business office. This NESC — resources granted specifically for the • Software organization exists. It is called the NASA purpose of proactively answering technical • Structures Engineering and Safety Center (NESC). challenges faced by their disciplines that may impact NASA’s programs in the future. Future Technical The NESC Model 2. NESC Chief Engineers Fellow Disciplines The NESC provides objective engineering • Electrical Power and safety assessments of NASA’s high risk Each Center plus Headquarters has an NESC • Passive Thermal projects, following the principle that safety Chief Engineer (NCE). The NCEs provide in- • Space Environments is achieved through engineering excellence. sight into the programs that impact their own • Cryogenics By searching out all of the resources Centers. They also help coordinate the fa- • Sensors/Instrumentation available, the NESC creates successful cilities and resources of each Center as re- • Systems Engineering broad-based teams by tapping into the best quired to support NESC assessments and the Agency has to offer. Although based at activities. the Langley Research Center, by design, the NESC maintains a decentralized framework 3. Systems Engineering Office (SEO) with members located at all of the Centers The Systems Engineering Office provides including Headquarters. Then by reporting system engineering and integration for directly to the NASA Chief Engineer, the NESC assessments and other NESC activities. The maintains a separation from the mission SEO and the SEO-led Systems Engineering directorates and their programs, and from TDT provide technical expertise in systems

46 NESC Overview

engineering processes such as systems perts that have been recruited from industry, analysis, statistics, data mining and trending, academia, and other government agencies. and requirements analysis. In the 5 years since its creation, the NESC has advanced the art of bringing such a di- 4. Principal Engineers Office (PEO) versity of individuals together to benefit the The PEO is responsible for technical assess- entire Agency, its Centers, its programs, its ments carried out by the NESC. The Prin- projects, and its people. cipal Engineers (PEs) and back-up PEs lead Chief among these benefits are better-in- assessment teams – especially for those ac- formed stakeholder decisions on technical tivities that require the participation of mul- issues in the near term, and better Agency tiple disciplines – and provide guidance for decision-makers in the longer term. The assessments led by individuals from outside Agency also benefits from innovative solu- of the NESC. The PEs have the project man- Members of the NRB (NESC tions that result from the diversity that the Leadership Team) agement skills to complement the focused NESC intentionally builds into its teams. The • NESC Director expertise of the NASA Technical Fellows. Agency further benefits from the geograph- • NESC Deputy Director ically-dispersed networks of expertise that 5. Management and Technical • Chief Astronaut endure long after the teams are disbanded. Support Office (MTSO) • Chief Scientist Finally, Agency programs and projects ben- • Deputy Director for Safety The MTSO is the NESC’s business office. efit as the NESC’s safety culture is spread • Deputy Director for Because the NESC relies on support from across the enterprise. many companies and agencies outside of Advanced Projects • MTSO Manager NASA, an effective business office is essen- Partnerships tial to handle the budgetary and contracting • SEO Manager To take advantage of expertise available • All Principal Engineers challenges faced by the NESC and the tech- outside of NASA, the NESC has leveraged nical aspects of setting up and maintaining • All NASA Technical Fellows partnerships with other government agen- • All NESC Chief Engineers partnerships. cies such as the National Transportation Safety Board, the Federal Aviation Adminis- 6. Office of the Director tration, and the Department of Defense. The In addition to the Director and his Deputy, NESC has also enlisted the resources and the Office of the Director includes a Deputy personnel of national laboratories and inde- Director for Advanced Projects and a Deputy pendent research organizations like Sandia Director for Safety. Also under the Director’s and Lawrence Livermore National Laborato- Office are the Chief Scientist and a represen- ries, Southwest Research Institute, Los Ala- tative from the astronaut corps detailed to mos National Laboratory, and the National the NESC as the NESC Chief Astronaut. Institute of Aerospace. Other participants –––– for NESC activities are pulled from industry partners ranging from large aerospace com- NESC Review Board (NRB) panies such as Alliant Techsystems, Boeing, The NESC leadership team meets weekly as Lockheed Martin, and The Aerospace Corpo- the NESC Review Board. All decisions made ration, down to smaller companies and indi- by the NESC are products of the NRB. Each vidual consultants. member has equal footing and brings his or Services for the Agency her background to the decision-making process. The success of the NRB results from The NESC’s primary vehicle for pursuing its broad diversity and the outstanding tech- engineering issues is the assessment. As- nical competence of its members. sessment teams are formed by pulling in technical experts from the TDTs and other Broad-based Teams sources to create a tiger team atmosphere The NESC builds networks of technical ex- that is focused on a specific technical is- pertise with discipline specialists that are sue. Requests for NESC assistance come selected from all 10 NASA Centers. These from various sources: Associate Administra- broad-based teams work on NASA’s most tors, program/project managers, scientists critical issues, together with additional ex- and engineers, NASA contractors, and even the general public. The level of participation — Continued on following page

57 NESC Overview

Accepted Requests by Continued from previous page Mission Directorate: 268 Total from the NESC in an assessment can range from the furnishing of expertise for consultation to a completely independent investiga- Yearly totals 4 54 46 57 56 51 tion with testing, modeling, and analysis. The 40 results from every assessment are published

35 in a final report that has been discussed and Space approved by the NRB. 30 Operations 25 The diversity and technical excellence of the

20 Exploration NESC also provides a centralized source from 15 Science which specific expertise can be drawn for

Accepted Requests other Agency needs such as technical review 10 General boards, mishap investigations, and situations 5 where real-time technical advice is required. Aeronautics 0 The NESC also provides a framework for 2003 2004 2005 2006 2007 2008 creating Agency-wide teams, with members brought in from around the Agency to participate in activities that extend beyond the NESC. Another important goal of the NESC Source of Accepted Requests: 268 Total is to educate. The NASA Technical Fellows share their insight and experience through the External to Agency 4% NESC Academy, in conferences and seminars, Program Analysis & NESC 28% and by encouraging junior level engineers to Evaluation <1% participate in TDTs. In fact, all members of the Anonymous <1% TDTs (over 600-plus), by interacting with the leaders of their engineering disciplines, gain Office of Chief experience and knowledge to bring back to Engineer 2% Engineering & Scientific their home Centers and organizations. Center Organization In summary Management 3% 38% Office of Safety and As NASA celebrated its 50th anniversary in Mission Assurance 3% 2008, the NESC observed its 5th. While the NESC as an organization has evolved over the Program Safety Mission past 5 years, the primary mission remains un- Management 16% Assurance at Centers 4% changed – to improve safety through engineering excellence. This Technical Update serves to highlight many of the activities that have succeeded by employing the NESC model, 2008 Technical Discipline Team Composition but the greater goal of the NESC is to foster the atmosphere of Agency-wide cooperation Other 1 % and set the example of the power of diversity to promote engineering excellence. Available University 4 % to anyone searching for an independent engineering assessment, the NESC can be reached through any NESC Chief Engineer or by email Other U.S. Gov. 4 % at [email protected]. More contact information and many NESC reports are available from the NESC website: www.nesc.nasa.gov. Industry 17 %

NASA 74 %

All statistics as of Nov. 12, 2008

8 NESC Overview

Upper shell of the Composite Crew Module (foreground) is being prepared for mating with the lower shell (background).

ATK

The NESC model: “I have witnessed the effectiveness of the NESC model, which brings together engineering talent from around the country to tackle difficult problems. While at times hard to manage, this inclusion of a diverse set of individuals with varied backgrounds and experiences, ultimately leads to better technical solutions.” – Mike Hagopian, Chief Engineer for Engineering Directorate, GSFC 79 NESC Academy

Learning from the Past n important function of the NASA Structures/Nondestructive Evaluation Technical Fellows Program is the (NDE) with NASA Technical Fellows A NESC Academy that was established Dr. Ivatury Raju and Dr. William Prosser to capture, share, and preserve the lifetimes and colleagues of experiences and knowledge of NASA National Institute of Aerospace, April, 2008 scientists and engineers and to guide the next generation of the Agency’s technical This course offered an overview of the staff in the art of technical problem solving. collaboration between the two major The key objective is to broaden NASA disciplines. This was not a course that focused engineers’ experiences and technical skills on equations, but rather took a broader view through interaction with the NASA Technical of concepts, processes and lessons learned. Fellows and selected members of their TDTs. Course topics included: Failure Prediction The ultimate goal is for each NASA Technical in Structures and NDE, System Integration, Fellow to have an opportunity to deliver their Structural Modeling and Analysis, Structural discipline-specific Academy course. Team Stability, Validation Testing and other related work. Imagination. Flexibility. Innovation. topics. Dr. Raju and Dr. Prosser collaborated All of these elements and many more have with other experts to bring to life the real been integral to the creation and growth of world issues faced during their extensive the NASA Engineering and Safety Center aerospace careers. (NESC) Academy, which celebrated its third year in operation in June 2008. To date, Innovative Engineering Design with the Academy has developed and offered Dr. Charles Camarda and colleagues 10 discipline courses in the classroom and has launched nine of them as online courses Penn State University, July, 2008 via the Academy website. Two courses, Innovative Engineering Design differed from Propulsion and Human Factors, have been previous NESC Academy offerings in that repeated. Courses have been provided to 368 the participants and instructors worked individuals from across the NASA Centers. and played hard together in the creative This year the following courses environment of the Penn State Learning were offered: Factory. Design methodologies ranged from “skunk works” — like rapid prototype Loads and Dynamics with NASA development — to current launch vehicle Technical Fellow Dr. Curtis Larsen development programs, and focused on the and colleagues conceptual design phase. Students learned techniques to leverage their creative thinking The University of Houston at Clear Lake, Dec., 2007 and to apply innovative, hands-on design Understanding loads and dynamics is critical methods in solving real vehicle design to NASA’s mission, a mission that includes problems. Dr. Camarda mixed academia with safe and reliable human and robotic space faculty from Penn State, MIT, and Georgia travel and air transportation systems. Loads Tech with aerospace experts to immerse and dynamics combines mathematics, the students in a “Space Boot Camp-like” physics, statistics, probability, structural and experience. mechanical engineering, and systems theory into one field vital to the safety and success Repeat courses offered this of every NASA mission. An emphasis of the year included: course was that loads and dynamics problem Space Propulsion Systems with mitigations were “trade-offs” for other areas Mr. George Hopson and colleagues (e.g., payload), so it is a balancing act requiring teamwork to make a mission successful. The Tulane University, May, 2008 Academy emphasized lessons learned from The encore delivery of Space Propulsion Sys- past experts. tems was presented by George Hopson and

10 NESC Academy

colleague Len Worlund. Hopson’s four decades of contributions to America’s space NESC Academy courses available program include work on Skylab, the Space online and the course leader Shuttle, and the International Space Sta- tion. In this two-day course, Mr. Hopson ■ Active Thermal Control and Life Support who worked with the renowned Werhner von Systems: NASA Technical Fellow Hank Rotter Braun, shared stories from meetings with von Braun and gave his guidance and insight ■ Space Propulsion Systems: George on: lessons learned, best practices, problem Hopson solving/resolution, Agency knowledge being ■ Power and Avionics: Robert Kichak lost, working at NASA, and latest trends. ■ Satellite Attitude Control Systems: NASA Human Factors with NASA Technical Technical Fellow Neil Dennehy Fellow Dr. Cynthia Null and colleagues ■ Human Factors: NASA Technical Fellow, National Institute of Aerospace, June, 2008 Dr. Cynthia Null Dr. Null’s expertise in human factors bridges academia and aerospace. This ■ Software as an Engineering Discipline: was an encore performance of the original NASA Technical Fellow Michael Aguilar classroom offering. The course content ■ Materials Durability – Understanding focused on the integration of human factors Damage Modes: NASA Technical Fellow into NASA missions from conception through Dr. Robert Piascik operations to include detailed case studies and problem-solving activities. Topics ■ Loads and Dynamics: NASA Technical Fel- included: Developing in-space systems, low Dr. Curtis Larsen Procedure development, Maintenance and ■ Structures/Nondestructive Evaluation: manufacturing, Control center design and NASA Technical Fellows Dr. Ivatury Raju and Ground operations. Dr. William Prosser

More information can be found at: http://www.nescacademy.org

The NESC Academy experience: “I’m a new engineer with NASA working with the crawler transporter. This course has been a great opportunity to hear the cumulative knowledge of all the teachers here, as well as a lot of the students sharing their knowledge base from their different projects.”

– Gordon Coffey, Kennedy Space Center, student at Academy Structures/NDE course 119 Technical Highlights

Finite element model (FEM) of the Orion Crew Module with FEM crash test dummies used to study crew seat design effectiveness against launch vibrations and landing impacts.

12 Technical Highlights

Exploration

Collecting Flight Force Measurements to Improve Coupled Loads Analysis Problem: Traditionally, accelera- forces and moments may be de- tion measurements are used to re- rived. The NESC is developing construct flight loads in structures. methodologies to predict interface The penalties of using only accel- forces based on these strain mea- eration are the weak correlation of surements that will be validated in Coupled Loads Analysis (CLA) and ground testing. The PAF design conservative qualification test- used on this flight is the most suit- ing. Thus, a need exists to utilize able test article for resolving forces force measurements in the CLA based on strain measurements. process. Force measurements will greatly benefit all future missions Results: GLAST was successfully and could assist the Orion Crew launched in June 11, 2008. Post- Module requirements and devel- flight data analysis is complete and opment process. Boeing employees Gerry Darter (left), Henry Fung (center), flight coupled loads reconstruction and Eric Thomas (right) install instrumentation on the GLAST underway. The next step consists NESC Contribution: An NESC PAF to collect flight force measurements. of reconciling flight-based forces team is demonstrating the bene- with flight reconstruction and/or fits of acquiring interface force measurements during flight. nominal coupled loads results. The team will investigate A simplified approach was used that involved mounting of the benefits of flight force measurements and the force pre- strain gages on the trussed Payload Adaptor Fitting (PAF) diction methodologies developed for use in ground testing of the Gamma-Ray Large Area Space Telescope (GLAST) to eliminate or substitute the use of strain gages in future spacecraft, now called the Fermi Telescope, in a way that launch vehicle flights.

Analysis of Constellation Program Mass Properties Problem: The NASA Constel- collection, accounting, reporting, lation Program (CxP) Chief En- adherence to standards, gineer requested an indepen- and the results of applying a dent assessment to review and method that assessed weight compare the current CxP mass as a function of design maturity. and performance management Recommendations incorporated implementation against industry specifics for refining the CxP practices. mass properties processes, thoroughly engaging the system NESC Contribution: The designers in managing mass NESC investigated: standards growth, and improved practices terminology, mass and for tracking and measuring the performance data capture and Lockheed Martin Corp. mass growth risk. Results are reporting, mass properties and being implemented to improve margin management plans, the overall accuracy of current mass margins, mass growth mass properties and performance The number of parts on the Crew Exploration Vehicle, Orion, allowance (MGA), launch processes, ongoing analysis and vehicle performance reserves, and other CxP components requires accurate knowledge of mass properties and its effects on the vehicle’s performance. reporting. integrated performance Lessons Learned: Programs margins, and sequential mass and projects should recognize and incorporate the discipline properties. The NESC team also reviewed the current of mass properties management early in the project life project calculations and reporting of predicted mass, MGA cycle. Implementation of mass properties management, and project management reserve, and identified methods to requirements and practices should be based on industry assess margins with respect to maturity and project phase. standards, use of consistent terminology, data collection, Results: Findings addressed details in terminology, data margin measurement and reporting methodology.

13 Technical Highlights

Exploration

Steve Skelley, a propulsion engineer of the MSFC’s Fluid Dynamics Branch, studies the assembly of the solid rocket motor airflow test rig. The rig in- ternally replicates the wetted surfaces of the RSRM at specific times in the burn. The proposed design modifications for reducing the thrust oscillations will be tested in this rig to verify their effectiveness.

Prediction and Reduction of Ares SRB Thrust Oscillation Problem: The Ares I vehicle has a thrust oscillation sources of propulsion system instabilities. Using the UCDS frequency close to the vehicle’s second axial structural mode simulation, the team identified and cataloged the design frequency. The NESC was asked to make an independent features that cause thrust oscillation and their individual prediction of the thrust oscillation in the five segment contribution to the overall oscillation amplitude. Design Reusable Solid Rocket Motor (RSRMV) and to develop options for eliminating and/or reducing the contribution of motor design change options for reducing or eliminating it. individual design features were developed and analytically evaluated using UCDS. The best options were provided NESC Contribution: The NESC team included personnel to the NASA Constellation Program-chartered Thrust from JSC, MSFC, LaRC, Gloyer-Taylor Laboratories LLC Oscillation Focus Team and the Ares project. (GTL), ATK, and Jacobs Engineering Group. GTL provided access to key expertise at Penn State University, the Results: Independent confirmation of the predicted RSRMV California Institute of Technology, and at the University of thrust oscillation frequency and amplitude characteristic Tennessee Space Institute. Additionally, GTL provided was achieved. The specific contribution of individual design expertise with their Universal Combustion Device Stability™ features was quantified for the first time. This provides (UCDS) system that predicts and identifies the specific design very valuable information to address the thrust oscillation phenomena. Variability seen in thrust oscillations can be accounted for by inhibitor protrusion height and edge shape variability. With measured control of the regression rate of the inhibitors, particularly in the aft of the motor, substantial reduction in oscillation amplitudes could be achieved. Specific suggested design improvements will be experimentally assessed by the Ares project. Introduction of the most successful modifications will be evaluated as a potential upgrade in the future. Lessons Learned: Aerodynamic streamlining principles apply within a rocket combustion chamber in the same manner that they apply in external aerodynamics. By applying aerodynamic streamlining principles inside rocket Data from the shuttle RSRM ground test at Promontory, Utah was used combustion chambers, the dynamic stability of the motor to validate thrust oscillation models. can be substantially improved.

14 Technical Highlights

Exploration

Review of the Launch Abort System Motor Qualification Plan Problem: The Launch Abort System (LAS) system for agreed that the qualification plan as proposed by the motor Orion includes three new design solid rocket motors (SRM). suppliers for LAS can provide adequate demonstration that The supplier team has baselined a qualification program for the motor designs are robust and have sufficient margins. the three SRMs (Abort Motor, Attitude Control Motor, and A list of 10 conditions was supplied as part of the report. Jettison Motor) while the government propulsion engineering Included in these conditions was that all design and team proposed a larger, more comprehensive set of performance requirements must be verified as a part of the qualification tests. To implement the larger qualification formal qualification program by a combination of tests and test matrix would significantly impact the baselined LAS analyses, and that design and manufacturing processes qualification program. The LAS Project should be mature at the beginning of Office asked the NESC to conduct an full scale qualification motor testing. independent assessment and provide a It was also noted that effective, clear, recommendation as to what is required and timely communication must occur to qualify the three LAS SRMs. between the motor suppliers and the NESC Contribution: The NESC government engineering team. formed an independent review team A minority view was expressed on the of experienced engineers, including NESC team that the baselined motor industry experts, consultants, and qualification plans are not acceptable retired NASA personnel to conduct and that it is improbable that there this assessment. Both the supplier will be sufficient data necessary to and Government LAS teams provided establish that the motors meet all the data for their approaches to LAS key requirements at the end of the SRM qualification and their rationale proposed qualification program. One showing the logic for their approaches of the premises of this perspective to qualify the motors for human space is that the LAS motor’s design flight application. departs significantly from previous The NASA and Orion industry team conducted Results: The NESC team conditionally a successful test firing of the LAS abort motor. configurations.

Ares I-X Upper Stage Simulator Project Independent Structural Review Problem: The NESC was requested to perform an Element Model (FEM) development was generally good, independent review of structural design calculations utilizing industry accepted methods. Concerns with the and modeling of the Ares I-X Upper Stage Simulator use of linear triangular elements were mitigated due to high (USS) and report any recommendations associated with margins of safety provided by the structural design. Some the design methodology or structural minor issues were identified and addressed integrity, including any need for additional by the USS Project. Adequate capability mechanical testing. of the segment-to-segment bolted joints NESC Contribution: The NESC team was demonstrated by test and analysis, consisted of the NASA Technical Fellow for with adequate “as-designed” margins of Loads and Dynamics, the NASA Technical safety. Final “as-built margins” following Fellow for Structures, and experts flange machining to reduce gapping were from MSFC, ATA Engineering, Quartus not available for review. Existing design Engineering, and Applied Structural and analysis for other structure and joints Dynamics. was found adequate for proposing use of “no-test” factors of safety. Results: The NESC team found that the USS Project stress analyses were conservative Lesson Learned: Consistent application and robust, followed industry accepted of FEM best practice techniques within an methods, and provided high margins of organization can be improved by training, safety via the structural design. Finite mentoring, and internal peer review.

Ares I-X illustration 15 Technical Highlights

Exploration

NGC Calspan Apollo and Shuttle veteran T.K. Mattingly and Karrie Trauth, Northrop Resident Engineer Geminesse Dorsey prepares an eight percent scale Grumman, discuss large scale composite structure fabrication. model of the MLAS fairing for wind tunnel testing at the Calspan facility.

Max Launch Abort System Risk Mitigation Project Problem: The launch abort system (LAS) for the Orion crew demonstration of an alternative landing system configuration exploration vehicle will provide a means of automatically for CM recovery. separating the crew module from the launch vehicle in The MLAS team is comprised of over 150 engineers, the case of emergency while on the launch pad through researchers and analysts from across the Agency and ascent to orbit. As a risk mitigation effort for the technical development of the Orion launch abort system, the then industry. NESC has partnered with the Wallops Flight Facility Associate Administrator for the Exploration Systems Mission for the pad abort test to leverage both their launch range and Directorate requested the NESC design, build, and test an sounding rocket development expertise. To minimize the alternative concept independent of the development and manufacturing time, project development. the MLAS team is employing existing As a resident engineer, meeting technology and off-the-shelf hardware NESC Contribution: The Max Launch and working with people from the to the greatest extent possible. The Abort System (MLAS), named after full-scale composite fairing is being Maxime (Max) Faget, a Mercury-era entire NASA Agency has been an manufactured by Northrop Grumman pioneer, will be theoretically capable interesting learning experience. Ship Systems in Gulfport, Mississippi. of extracting the CEV from the launch The four MK-70 solid rocket motors are vehicle at any time from crew ingress The One NASA concept is alive surplus US Navy motors obtained from at the launch pad through staging the Wallops sounding rocket inventory. and successful ignition of the second and well on the MLAS Team! or upper stage of the Crew Launch —Terrian Nowden, MLAS The MLAS team has also capitalized on Vehicle (CLV). The MLAS Flight Test Resident Engineer, GRC an opportunity to share lessons-learned will culminate with at least one full- and pass on corporate knowledge by scale unmanned pad abort test to bringing Apollo-era veterans as mentors demonstrate the viability of this alternate concept. In order and advisors together with junior engineers with 5-10 years to be timely and relevant to the Constellation Program, the of experience. The mentors have provided the MLAS NESC was challenged to complete this first flight test in team with first-hand knowledge acquired while building a parallel with the Orion LAS Pad Abort Test 1. human-rated spacecraft. The junior engineers, referred to The MLAS flight test vehicle is designed to lift the crew as Resident Engineers based on the concept of medical module (CM) simulator from the launch pad to an altitude residencies, are getting hands-on experience with the entire high enough and with enough distance downrange to allow design, build and test life cycle. The multi-generational the CM to execute a nominal landing. The MLAS pad abort nature of the team has been rewarding and enriching for flight test will demonstrate a passively controlled coast all involved and is helping to meet the goal of expanding phase, reorientation and extraction of a CM simulator from NASA’s experience base in fast turnaround design and the fairing. The test will also include a landing parachute development projects.

16 Technical Highlights

Exploration

Technicians prepare the forward fairing nose ring for installation.

Forward Fairing

CM Simulator The full scale Orion Crew Module simulator being prepared for mass properties measurements.

MLAS major Coast Skirt structural components

Boost Skirt

One quarter of the composite forward fairing being lifted in the Wallops Payload Processing Facility.

Photos and graphic/NASA

Technicians install an inert separation joint in the bottom of the Coast Skirt.

1517 Technical Highlights

Wind tunnel testing of the Orion Crew Module separating from the MLAS forward fairing.

Univ. of Washington

On Multi-Center Teams: My membership on the Materials TDT has provided me the opportunity to work with many people at the space flight Centers... Often the space flight Centers don’t understand the value of research Centers until our unique capabilities solve their real problems.

– Brian Jensen, Senior Researcher for Advanced Materials, LaRC, Materials TDT 1816 Technical Highlights

Exploration

New Shell Buckling Test Facility at MSFC used for testing 8-ft-diameter cylinders subjected to combined compression, bending and internal pressure.

Updating of Launch Vehicle Shell Buckling Knockdown Factors Problem: The NESC Shell Buckling Knockdown Factor has enabled an efficient working relationship between the Project (SBKF) was established in March 2007 to develop Centers. and validate new analysis-based shell buckling design Results: In FY08, the SBKF project designed and factors (a.k.a. knockdown factors) for Ares I and Ares fabricated a new test facility to test 8-ft-diameter cylindrical V metallic and composite launch vehicle structures. shell structures subjected to combined axial compression Improved, i.e., less-conservative, knockdown factors will and bending. Two 8-ft-diameter, 2195 Aluminum-Lithium enable significant weight savings in these vehicles and will (Al-Li) orthogrid cylinder test articles have also been help mitigate some of NASA’s designed and fabricated. The launch vehicle development and first test article was successfully performance risks. tested in November 2008 NESC Contribution: The NESC and the second article will be has supported a significant tested in January 2009. Sub- portion of the SBKF Project, component tests of 2195 Al-Li including funding for the design orthogrid stiffened panels are and fabrication of a large-scale being conducted at LaRC to test facility and the first series investigate local skin pocket of large-scale buckling test buckling and stiffener crippling articles, programmatic and behavior. This test data is being technical support, peer reviews, used to assess the current and advocacy. In addition, the design approaches for these NESC has helped coordinate structural details and validate activities between LaRC and new high-fidelity numerical Dr. Mark Hilburger (left) and Dr. Robert Thornburgh (right), struc- MSFC, the two primary centers tures engineers from LaRC, monitor test data during the shell simulations of common Ares- involved in this project, and buckling test at MSFC. like structural details.

19 Technical Highlights

Exploration

ATK (Foreground) The lower shell cured inner skin on the lower shell cure tool. (Background) Aluminum honeycomb core on the upper pressure shell following the core tack cycle at the ATK factory in Iuka, MS. Composite Crew Module Pressure Vessel Pathfinder Development

Problem: In 2006, the NESC studied the feasibility of Techsystems, Bally Ribbon Mills, Collier Corporation, a (primary structure) composite crew module for the Genesis Engineering, Janicki Industries, Lockheed Martin, Constellation Program Crew Exploration Vehicle. The and Northrop Grumman. overall finding indicated a composite crew module was The composite crew module team operates in a virtual feasible, but a detailed design would be necessary to environment, electronically connecting participants across quantify technical characteristics, particularly in the areas the country. During the design phase, the team constrained of mass and manufacturability. Subsequently the NASA the design to match interfaces with the then current Orion Administrator, Associate Administrator for the Exploration crew module including the internal packaging constraints Systems Mission Directorate, and the Constellation Program that utilize a backbone for securing internal components. Manager chartered the NESC to design, build, and test a The team evaluated design solutions and focused on a composite crew module structural test article with the goal design that utilizes aluminum honeycomb sandwich and of developing a network of Agency engineers with hands- solid polymer matrix laminate material systems. One on experience using structural composites on complex unique feature of the composite crew module design was habitable spacecraft design. The NESC Composite Crew the structural integration of the packaging backbone with Module (CCM) Project was chartered in January of 2007, the floor and pressure shell walls. This provides aload with a goal of delivering a full-scale test article for structural path that accommodates load sharing with the heatshield, testing 18 months after project initiation. especially for water landing load cases. Another unique NESC Contribution: Led by the NESC, the project feature of the composite design is the use of lobes between team is a partnership between NASA and industry, which the webs of the backbone. This feature puts the floor into a includes design, manufacturing, and tooling expertise. membrane type loading resulting in a lower mass solution. Partners include civil servants from ARC, DFRC, GRC, Connecting the floor to the backbone and placing lobes GSFC, JSC, JPL, KSC, LaRC, MSFC, the Air Force into the floor resulted in mass savings of approximately 150 Research Laboratories, and contractors from Alcore, Alliant pounds to the overall primary structure design.

20 Technical Highlights

Exploration

(Far Left) Dr. Dan Polis (on floor), CCM Materi- als lead, GSFC, and Mike Kirsch, NESC (on ladder), installing pre-preg carbon fiber fabric ply on the inner mold line skin.

(Left) A tool proof of the upper pressure shell is extracted at the tooling vendor, Janicki Industries in Sedro-Woolley, WA. The tool proof was created to validate that the tool draft angle was sufficient to extract the part.

Janicki Industries

The design is constructed in two major components: an of its design. It also posed a significant threat to the Orion upper and lower pressure shell. The two halves are joined schedule because of the manufacturing changes required in a process external to the autoclave to enable subsystem by composite versus metallic materials. However, because packaging of large or complex subsystems. The initial of the advantages of the split clam shell design found on and preliminary design concepts were reviewed by an the composite crew module, Orion is considering adopting independent review panel in March and June 2007. The this approach for their aluminum-lithium configuration. team conducted building block testing of critical design Lessons Learned: Design lessons show that non- and technology areas, which were used to validate critical autoclave splices allow concurrent fabrication, assembly, assumptions and design allowables for the final design. The and integration of major structural components and detailed design was reviewed and approved in December subsystems, and provide a lower cost cure tooling option. 2007 by an independent review panel. Full-scale fabrication of the upper and lower pressure shells began in February Through the use of complex shapes enabled by composites 2008, and post-cure assembly operations a membrane lobed floor integrated with started in late May. The project plan is backbone subsystem packaging feature to statically test the combined upper and Apollo offers a weight savings. A honeycomb lower shell assembly to verify that the core, combined with mature secondary analysis models predict the response of attachment technology, provides flexibility the structure under load, and then repeat and robustness in secondary attachment the static tests with internal pressure up to locations. As loads and environments 30 psi. Testing is scheduled to occur at change with program maturation, inner LaRC in March 2009. mold line tooling offers the opportunity to optimize or change design through tailoring Results: In September 2008, the Orion of layups or core density. Composite CCM project was asked to evaluate the solutions offer opportunity for lower piece- implications of adapting a composite crew part numbers resulting in a lower drawing module in the baseline Orion design. A count which helps minimize overall life tiger team was formed between Orion and cycle costs. Also, a minimal number of the NESC composite crew module team tools are required to manufacture the to evaluate opportunities and challenges. primary structure. Thermal and dynamic At this stage of the overall Orion vehicle property differences from aluminum are design, the composite crew module does under investigation; however, preliminary not appear to offer significant mass or unit Illustrations of the Apollo estimates do not indicate that composites cost savings because of the complex nature and CCM pressure vessels. create system level issues.

21 Technical Highlights

Exploration

Improved Crew Seat Attenuation Designs for the Orion Crew Module Problem: The Orion Project distance to absorb more energy requested alternate seat attenuation in the spine axis direction. The designs to be developed and second concept focused on analyzed for the Crew Module (CM) providing isolation at the strut- with primary emphasis to provide pallet interface. The NESC team improved crew survivability for developed simplified dynamic nominal water and Contingency response models and utilized the Land Landing (CLL). The NESC Orion baseline seat attenuation was later asked to evaluate crew models to examine a range of seat design options to reduce pallet isolation properties for the effects of the Ares thrust crew landing attenuation. This oscillations problem and its effect Resultant led to a request from the Orion on landing loads. velocity Project to examine mitigating vector NESC Contributions: The assess- the effects of Thrust Oscillation ment team consisted of designers (TO) from the Ares stage 1 and analysts from multiple NASA solid rocket booster on the centers including GSFC, JSC, JPL crew using isolation concepts. The NESC worked to improve impact attenuation in the and LaRC, contractors, academia, Z-axis (along the spine) of Orion crew members. Coupled loads models for NASCAR seat design experts and launch and landing models were engineers from the Apollo era with used to examine the optimal TO design and test experience on its landing systems. Prior to isolation frequency that would minimize crew loads during developing alternate concepts, assessment members had all phases of the Orion flight. Hardware design concepts the opportunity to evaluate the seat attenuation systems in for implementation of this feature have been generated and the Apollo XVII Command Module, and in mockups of the specific recommendations for the baseline seat system such Soyuz and Orion CM. as the shoulder harness attach point were also developed. Results: The Orion baseline crew seats are located on a Isolation system models showed reduction in the impact rigid pallet, which is suspended in the volume of the CM by acceleration forces experienced by the seat occupant in load attenuating struts. The struts attenuate the loads to all three axes for most load cases over the Orion baseline the crew when the pallet is accelerated in response to an design by reducing the dynamic amplification portion of the external force applied to the CM. An Orion landing (water or load for crew response in the axis along the crew spine. land) orients the CM such that the reclined crew impacts the The NESC team is planning to evaluate smart materials and earth’s surface “feet first”, resulting in a major force vector active systems to improve the strut performance over the along the axis of the crew’s spine. Analysis performed baseline. Results from the TO study confirmed the optimal by NESC members assisting with finite element modeling crew isolation frequency of 4.5Hz and revealed a potential of Orion occupant injuries found problem with a rocking mode of that improving the lateral restraint the crew seat should isolation of the crew as well as holding the be implemented at that location. crew tighter in a conformal seat The team also examined pallet reduced injury risk. An NESC seat isolation and found that approach design expert developed and tested to be more appealing from a mockups of improved harnessing load mitigation perspective. techniques to achieve these results. Isolating in series with the The team focused detailed design pallet struts has a lower effect and analysis effort on investigating on crew landing loads than the effectiveness of incorporating an seat isolation and a higher isolation system between the seat probability of successful pallet and the CEV pressure vessel implementation. The NESC structure. Two concepts emerged. team continues to evaluate updated load cases and refine The first tilted the crew pallet during NESC team member Pete Rossoni performs a fit check in landing to provide a greater stroking an Orion seat mock-up at JSC. the hardware design concept.

22 Technical Highlights

Exploration

Improving Orion Crew Impact Tolerance Modeling Problem: Reliable injury predictive tools and injury criteria materials, side constraints, flailing of limbs, and detailed are required for protecting Orion crew members during seat/occupant interactions to minimize landing injuries to water and land landings. While conventional tools used in the crew whereas the whole body models do not provide the aerospace community typically lead to safe designs, this level of detailed assessment. This information will they may be overly conservative — resulting in additional be used to understand trends in occupant protection and complexity and increased system mass. Alternate to define acceptable injury criteria associated with seat approaches, such as those used in the automotive industry, restraint and attenuation systems. An accurate crew injury may provide more fidelity; however, their application to tolerance model would allow any changes to the Orion Orion requires modification and study. structure, seat attenuation system and landing conditions NESC Contribution: The NESC is supporting the Orion to be examined for its safety effects on the crew. Project’s investigation in the use of crash test dummies for Results: While this work is ongoing, results thus far indicate assessing injury risk for the Orion crew. The study objective is to better predict loads on the crew during water and land the crash test dummies used in conjunction with the landings. Results from finite element math models and Brinkley criteria provide a useful set of tools for predicting physical sled tests with the dummies are being compared and eliminating potential crew injuries. The finite element to the whole body injury models commonly referred to as math models developed in support of this task have also the Brinkley criteria, which have been typically used for been used to evaluate proposed designs by the NESC team aerospace applications. The crash dummy models allow investigating alternate landing attenuation and isolation for assessing the occupant restraint systems, cushion systems.

Finite Element Hybrid III crash test dummy models represent the Orion crew members. Dr. Charles Lawrence, GRC, (right) developed this integrated model of the Orion crew module and seat attenuation system.

23 Technical Highlights MLAS team members lower the Crew Module Simulator into a mass properties measurement fixture.

Developing professional relationships: ...by working with people outside your normal sphere of influence, you meet individuals who are able to challenge you and who help bring out the best in you… and vice versa. A mutually beneficial relationship develops, the projects become more exciting, and the quality of work is superbly better than the sum of what the individuals could have produced.”

– Dawn Phillips, MSFC, Structures TDT 2422 Technical Highlights

Science

77K cryogenic temperature Room temperature

Optical cross-section at 30X of ribbon cable harness after High Velocity Impact testing. Harness was impacted by a 0.20mm diameter Sodium-Lime- Glass projectile at 6.92 km/s at 0˚ impact angle. The impact in left image was at a cryogenic temperature and indicates damage of lesser depth but includes cracks marked by red circles compared to room temperature impact on right.

Hypervelocity Particle Impact Resistance of JWST Electrical Cables Problem: The James Webb Space Telescope (JWST) cable harnesses from meteoroid impact damage. uses a series of fine gauge wires and cables to interconnect Results: The harness exposure, spacecraft orbit, and the cryogenically operated (35K) optics and detectors to meteoroid environment as well as harness impact testing the warmer (~300K) electronics of the Integrated Science results were combined to predict the probability of ISIM Module (ISIM). It was proposed that these cables, which mission success. This mission success prediction was then are exposed to direct meteoroid flux in the Earth-Moon L2 compared to the mission success requirement to define the environment, can be damaged by the meteoroids. necessary meteoroid shielding. The historical approach to NESC Contribution: The NESC conducted an independent meteoroid protection was also reviewed. One unexpected study of the cryogenic cable harnesses vulnerability and result found during testing was a large deviation between shielding requirements for the ISIM. Hypervelocity impact damage predictions and test results. Damage was (HVI) tests were conducted that provided data on particle estimated from the extrapolation of an analytical damage size/energy at the failure threshold for the ISIM’s exposed equation — valid for aluminum shields — to shields of cables, and evaluated shielding options to protect the ISIM different metals and compared with the test results. The extrapolated damage equation predicted better shield performance than the tests showed. The effects of cryogenic temperature were assessed on harness damage tolerance. The results showed that ambient temperature impact testing was adequate because less damage was seen at cryogenic temperatures. To cool the test articles in the vacuum chamber of the test range, an enclosure was built to insulate against convection, conduction, and radiation. A pressure system delivered cryogenic gas to the enclosure. One result was that the conductors within the ribbon cable assembly (silver-colored spheres in the cross-section above) apparently moved during impact, and thereby sustained less damage than had been expected for these types of impacts which did not fully penetrate or pass through the harness. HVI testing was also performed to study the contamination potential from micrometeoroid WSTF impact on the Aft Optics Assembly (AOA) Dennis Garcia, WSTF (right) uses a mirror to view inside the JWST cryogenic box to verify impact on target. Paul Mirabal, WSTF (left) verifies projectile integrity post test on the light enclosures from debris generated by high speed imaging system. penetrations through the enclosures.

25 Technical Highlights

Science

Risk Assessment of Kepler Reaction Wheel Premature Failure Problem: One of the Reaction Wheel Assemblies (RWA) the effects of misalignment. The team also evaluated the that is used to provide attitude control authority and stability change in bearing lubricant film thickness as a function of on the Thermosphere, Ionosphere, Mesosphere Energetics rotational speed and operational temperature. The results and Dynamics (TIMED) spacecraft, failed in February, 2007 of these tests and analyses fed into the short term and long after five years of continuous operation on orbit. Four term recommendations for the unit. RWAs of similar design have failed after two and a half years The NESC team also reviewed operational strategies for operation on two other spacecraft. The RWAs on the Kepler use of the Attitude Control System (ACS) with the Kepler spacecraft, due to launch in early 2009, are identical to the Chief Engineer and the lead ACS engineer at the prime TIMED RWAs. Based on the contractor. The strategies results of a Jet Propulsion would maximize RWA life by Laboratory (JPL) failure minimizing the total number investigation, the Kepler of RWA revolutions. Several Project directed that design operational recommendations changes and corrective previously not considered by measures be implemented the project resulted from these in the RWAs. Because the discussions and analyses. modifications were limited to minimize the overall impact to Results: The direct results the Kepler mission, the NESC of this assessment warranted was asked to assess the risk to both in process and post success of the Kepler mission assembly inspections and from a RWA failure, given the tests to reduce project risk. history of flight failures and Ultimately, it was determined the limited modifications that the robustness of the being implemented. ACS system (due to RWA redundancy) results in a low NESC Contribution: A multi- level of risk to meeting the discipline, multi-Center team project’s minimum mission was formed by the NESC objectives. The NESC team’s that included mechanism contributions provided the and tribology experts from Kepler Project Management GSFC, JPL and LaRC as the data required for their well as Industry consultants. overall mission performance The assessment of RWA assessments and on orbit anomalies and associated operational suggestions risk to the Kepler project was should an anomaly occur with broken into two parts. The two RWA units. first was an evaluation of the mechanism design and its ability to meet project life requirements. The second was an evaluation of the wheel usage. To evaluate the mechanism design, the NESC team performed analyses and tests and also used data that was available from other NASA tiger teams involved with this (Left) Kepler spacecraft showing the issue. A Ball Speed Variation location of two of the four Reaction analysis was performed on Wheel Assemblies. A reaction wheel the RWA bearings to assess is shown (above).

26 Technical Highlights

General

RTAX Risk Mitigation Testing Problem: Multiple projects across the Agency strongly desire to use the latest RTAX-S series Field Programmable Programming Initial testing ATE = Automatic Gate Arrays (FPGAs). These parts offer significant on ATE Test Equipment advantages over the use of the previous version RTSX-S or –SU regarding maintenance of signal integrity, capacity, capability, speed, and electrostatic discharge (ESD) Time, voltage, Life testing and temperature tolerance. Reported user failures in the previous generation profiles of FPGAs (RTSX-S) precipitated concerns late in the Repeat each hardware design cycle for several NASA projects, causing 1000 hours for ATE tests on 6000 hours total significant cost impacts and higher mission risks. These all parts concerns were not a result of the part performing in a clear failure mode condition, but rather a result of user application issues combined with unknown limitations of the original –S Detailed Report part with regard to marginal programmed antifuses. It is analysis on progress anomalies desired to avoid a similar late discovery of issues for the latest RTAX-S FPGAs. NESC Contribution: The NESC is conducting a test RTAX250S FPGA and RTAX2000S FPGA Test Plan. of 80 units (2 lots) of RTAX250S and 80 units (2 lots) of correction algorithm, a memory controller, and a Universal RTAX2000S programmed with an algorithm designed to Asynchronous Receiver/Transmitter. emulate expected space flight applications. The test will subject the parts to the voltage specification limit and to Results: The test was started in the second quarter of the temperature specification limit conditions. The selected Calendar Year 2008 and is expected to be finished in the representative space flight designs include multiple copies first quarter of Calendar Year 2009. The parts have passed of a Military Specification 1553 Remote Terminal interface, the 1000 hour point of a planned 6000 hour test. Preliminary an 8-bit micro-processor (PIC 16F84), an error detection and results have indicated no major issue at this time.

Entry, Descent, and Landing Data Repository and Analyses Task Problem: NASA and the Entry, Descent, and Landing (EDL) community lack a common repository of EDL data from previous Earth and planetary flight missions to aid in the design of future EDL systems. Recent missions to Mars will provide a wealth of information, however, much of the older data has been lost or is at risk of being unusable due to poor storage conditions. Some examples are: Viking EDL data and Viking design data (parachute tests); Planetary Atmosphere Entry Tests (from Wallops and Ames); Pioneer Venus (EDL); Galileo (ED); Magellan (aero-braking data); Project Fire (Apollo design and test data for re-entry); and Shuttle EDL test data. Illustration of Mars Exploration Rover entry. NESC Contribution: The NESC EDL Repository team is focusing on two aspects: (1) to locate, collect, and digitize 2008. Since then selected users from NASA and academia NASA technical and engineering EDL material, and (2) have used it to archive material. In addition to continued data to develop a secure, web-based repository (EDL-R). It addition, the remaining work includes documentation (user is password-protected and requires user-authorization guide, curator guide, etc.), and the implementation of some for sensitive documents. EDL-R has browse and search features such as Browse-by-Mission, Virus Check, etc. It is capabilities, email notification of new material, and will anticipated that the full system will be fielded in FY 09, and follow a strict Submit, Review, and Release life cycle. transferred to a NASA-selected Center for continued growth Results: Beta testing of EDL-R was completed in February and maintenance.

27 Technical Highlights

General

Development of DC/DC Converter Application Guidelines Problem: Hybridized DC/DC The guidelines document also converters are ubiquitous in flight covers a broad spectrum of general hardware designs, forming an information including applications important bridge between the overview, mission environments, spacecraft power bus and localized performance requirements, design users of power within instruments and practices, test methods, hybrid other electronic subsystems. These packaging and elements, quality parts are actually complex micro- levels, vendor-contract-related systems containing the same types topics, and handling and installation of elements that one would expect to precautions. The guidelines see on a printed circuit board except document also contains appendices all within a 12 inch2 package. For on DC/DC converter usage by many years they have been found project and failure history in NASA to inconsistently meet performance hardware, a DC/DC converter and quality requirements and to fail specification template, boilerplates catastrophically in flight hardware. for contract documents, and a The complexity and cost of these parts checklist for implementing this can have a severe impact on program guidelines document for a flight schedule and budget when a failure project. These can be used by occurs or can be mission-ending if projects to get a jump start on their the failure occurs in flight. Hybrid DC/ planned usage of DC/DC converters DC converter flight failures have been while eliminating many of the demonstrated or have been suspected typical problems that are often on several projects including GRACE, encountered. Hubble Space Telescope, and the Results: The document provides International Space Station. In addition, a practical set of guidelines numerous flight projects, both manned for characterization, selection, and unmanned, have had severe pre- purchase, and application of launch cost and schedule impacts due hybridized DC/DC converters in to hybrid DC/DC converter quality and NASA flight hardware to prevent or application issues. It is well established mitigate failures and risks in the field. within NASA that there is difficulty with The document describes practices converter specifications and how that that should be integrated into the data can be interpreted and used. Test images of a typical hybrid DC/DC con- following local processes: electrical NESC Contribution: The NASA verter: (top to bottom) cover removed, X-ray, system design and validation, Engineering and Safety Center thermal under load, and electron microscope electrical circuit design, thermal at 24 MHz. (NESC) funded the development of and packaging design, device a guidelines document to capture characterization and evaluation, the knowledge that projects seem to device qualification, device constantly re-learn about DC/DC converters, particularly selection, and device procurement and acceptance testing. converters of hybrid microelectronics technology. Testing The recommendations and guidelines directly address a of several types of DC/DC converters was conducted to history of problems NASA has encountered with this device develop a standard set of test approaches and procedures type. The document is meant to be used as a guideline; it is not mandatory and is not intended to be invoked as a for flight projects to use. This testing explored the operation requirements document by NASA Centers. Several current of DC/DC converters at different conditions (thermal, power projects have already started using this information. levels, etc.) to show where problems typically can be expected. The vendors were consulted regarding datasheet Lessons Learned: A NASA website has been developed improvements that provide additional types of information to track the usage of converters as well as any failures. important to projects. Standard tests, test procedures, These data will be used to ensure the lessons-learned are sample datasheets, etc. were developed and are included in communicated across NASA Centers, as well as being the guidelines document. added to the Lessons Learned Information System (LLIS).

28 Technical Highlights

General

HYTHIRM Validation and Calibration Testing Demonstration Problem: Predicting aeroheating of complex surfaces during hypersonic entry into an atmosphere is complex, Top driven by uncertainties in both boundary layer transition (BLT) onset and subsequent turbulent heating. The East West inability to accurately predict these phenomena with numerical turbulence models can impose unnecessarily large thermal protection system margins that translate Bottom to reduced payload capability and degraded mission performance. Global temperature infrared (IR) images with adequate spatial resolution and dynamic range could non- intrusively complement thermocouple data by providing spatially continuous surface temperatures at targeted Mach numbers. NESC Contribution: The HYpersonic AeroTHermody- Cast Glance aircraft IR image of the Shuttle tile array heated by the solar namic InfraRed Measurements (HYTHIRM) team, estab- collectors. (Inset) Image of non-uniform, top-to-bottom, heating of Shuttle lished by the NESC, undertook a field deployment to per- tiles with temperatures ranging from 2000 ° F to 500 ° F. form radiometric calibration and validation of the nation’s existing suite of land-based and airborne IR imaging assets Results: The HYTHIRM systems were successfully and tools for remote thermographic imaging. The test sub- calibrated and analysis of the imagery was used to evaluate ject was a Shuttle tile array heated to surface temperatures the performance of the IR imaging assets. The team typical of a Shuttle re-entry. The Sandia National Labora- demonstrated the viability of obtaining surface temperature tory’s National Solar Thermal Test Facility in Albuquerque, measurements of hypersonic flight vehicles, and more NM, was used to aim an intense solar beam at a 4 ft x 4 ft specifically, to reliably acquire, track and return surface panel of 64 Shuttle LI-900 ceramic tiles located on top of temperatures of the Orbiter during entry aero-heating and a 200-ft high tower (right). Thermocouples installed on the provide flight BLT thermography data. These data could array and an IR imager located in close proximity to the test be utilized for calibration and validation of empirical and target provided actual surface temperature conditions. theoretical aero-heating tools.

NESC Data Mining and Trending Working Group (DMTWG) Problem: The NESC is leading an Agency level Data joint development by the JSC Engineering Directorate and Mining and Trending Working Group whose purpose is to the University of Central Florida. This group provides a assist in the formulation and implementation of a capability forum to enhance communications across the Agency in to strengthen trending of NASA programs and projects, and the areas of data mining, trending, and statistics by sharing to ensure appropriate visibility of data mining and trending. ideas, methods, technologies, processes, tools, and Through workshops, monthly meetings, and training, the lessons learned. NESC has developed working relationships with data mining and statistical experts within academia, industry, and other government agencies. The NESC’s collaboration with other organizations has enabled cross pollination of ideas, particularly regarding methodology and lessons learned. NESC Contribution: The DMTWG is assisting NASA organizations in strengthening trending activities for the Agency’s programs and projects. This is being accomplished in part by developing a data mining toolbox including tools such as the commercial data mining software, SAS. The team is also aiding the development and implementation USA of linguistic data mining approach meant to ameliorate Delmar Foster, Senior Analyst for United Space Alliance, performs data terminology inconsistencies in problem reporting, under mining using SAS Enterprise and Text Miner software.

29 Technical Highlights

General

Probabilistic Requirements Verification Problem: Probabilistic requirements — those which include quantifiable uncertainty — occur in significant numbers in Constellation Program (CxP) requirements documents. Verification has sometimes been confusing or difficult for requirements owners and verifiers. A team was commissioned by the Constellation Chief Engineers Forum (CxCEF) to provide guidance for generating verifications with probability and confidence for both Monte Carlo analysis and all other applicable areas. NESC Contribution: The NESC provided expertise to the CxCEF team in statistics and probabilistic risk assessment (PRA) from several NASA Centers and academia through its Systems Engineering Technical Discipline Team’s NESC Engineering Statistics Team (NEST). Dr. K. Preston White (Left), University of Virginia, a key member of the probabilistic requirements verification team. Results: A pair of broadly-applicable templates modeling verification statements applicable to both probabilistic number of simulation trials necessary to prove verification of Safety, Reliability and Quality Assurance (PRA-type) and engineering performance requirements to the required risk engineering performance requirements. The templates level. For the NESC team, post delivery follow-up has been include: a “six-step” best-practice process for ensuring proven vital. Team members continue to supply consulting that verification is truly achieved; a tutorial glossary aimed services to CxP users on applying the recommendations. In at standardizing terms and explaining statistical concepts return, the team is learning how its recommendations could in engineering language; and a method for predicting the be extended to other programs.

Flight Battery Working Group Update Problem: Batteries are used in virtually every space discussed, and test programs were executed in the mission and the differences in the application, duration, generation of a series of recommendations and guidelines to and operations result in the use of a large array of batteries reduce risk associated with various aspects of implementing and, therefore, battery issues. In the past there has been battery technology in the aerospace industry. Over the no coordinated NASA-wide approach to the common past year, the working group, comprised of representatives issues. The large array of issues include: exceeding the from NASA Centers including GRC, JSC, GSFC, MSFC and recommended wet life prior to launch, recognizing cell JPL addressed (among others) the following technology degradation signatures, and understanding the features areas: Recommendations for Binding Procurements of and limitations. Battery Systems; Wet Life of Nickel-Hydrogen (Ni-H2) Batteries; Generic Safety, Handling and Qualification NESC Contribution: In 2006 the NESC chartered the Recommendations and Guidelines for Lithium-Ion (Li- NASA Aerospace Battery Working Group to carry out a Ion) Batteries; Generation of a Guidelines Document that series of tasks based on Agency-wide issues related to addresses Safety and Handling and Qualification of Li-Ion aerospace batteries. Studies were performed, issues were Batteries. Results: The working group published a report entitled “Generic Safety, Handling and Qualification Li-Ion Recommendations and Guidelines for Lithium-Ion (Li- spacesuit Ion) Batteries.” The document provides a summary of pouch aerospace Li-Ion battery performance, guidance for the cell. selection, design, operation and qualification of Li-Ion batteries, and specific guidance related to the use of pouch cells, commercial 18650 cells in high capacity, high voltage series/parallel strings, and recommendations for defining safe operational conditions for Li-Ion batteries.

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Space Operations

Investigation of ISS Solar Alpha Rotary Joint Issue Problem: As a result of high current, auto-tracking of the starboard Solar Alpha Rotary Joint (SARJ) was halted in 2007. The SARJ is a circular component that allows the truss to rotate to keep the solar arrays pointed at the sun. Inspection of the starboard SARJ revealed severe damage to the outer steel race with large quantities of magnetized debris present on both the race ring and trundle bearing assembly (TBA). The NESC was asked to support the International Space Station (ISS) Program anomaly root cause investigation team. NESC Contribution: NESC Mechanical Systems Technical Discipline Team (TDT) members and gear and tribology experts from GRC, GSFC and MSFC reviewed SARJ build records, consulted on lubrication solutions, and provided testing of root causes. NESC members inspected Magnetized debris seen on the SARJ trundle bearing assembly. Twelve the SARJ static test article and TBA returned from orbit, trundle bearing assemblies are equally spaced around the circumference of the SARJ and provide precision support and alignment during rotation supported vacuum roller traction rig testing at GRC, and of the SARJ. block on ring testing at MSFC. Results: The NESC’s efforts provided the necessary data their hypotheses with laboratory testing which resulted in to exonerate potential root causes such as incorrectly physical proof of the low friction benefit of gold surfaces. installed TBA rollers and led to the discovery that gold The ISS Program anomaly investigation team has adopted plating adhesion was an issue on several TBAs during the this as a very likely contributor to the SARJ anomaly and the initial build. Further investigation revealed that the gold NESC team continues to support them with the corrective adhesion issue might be a distinguishing characteristic action for short and long-term operations. between the current nominal operations of the ISS port SARJ Lessons Learned: The report for this assessment is not versus the anomalous starboard SARJ. The team validated yet complete and lessons learned are still in process.

Determination of EMU Space Suit Glove Damage Modes Problem: The number of Extravehicular are likely the result of glove contact with Mobility Unit (EMU) gloves damaged during off-nominal surfaces. The first damage extravehicular activities has increased. The mode noted was a linear separation of NESC is assisting a JSC Materials and Vectran™ fabric most likely produced by Processes team to identify glove damage a press-and-draw motion of the glove over modes. a relatively sharp surface severing multiple yarns along a single path and resulting in a NESC Contribution: The NESC assembled linear shaped hole. At each fabric weave, materials experts from LaRC, GRC, JSC, a higher region or crown of yarn is exposed the US Army and SRI International. The to rubbing contact with surfaces. The team (a) reviewed EMU glove materials, second damage mode, crown abrasion, manufacturing processes and testing, (b) Close-up of damage in the thumb is a common fabric damage mode and is examined ten damaged EMU gloves using a region on right EMU glove. characterized by severed frayed fiber ends unique NASA scanning electron microscope located on each side of the crown and flattened fibers at the facility with enhanced capabilities, and (c) conducted center of the crown. Finally, a snag-and-pull damage mode laboratory tests to duplicate observed microscopic damage was noted. The loose Vectran™ fabric weave is snagged by modes where different off-nominal surfaces were used to contact with an off-nominal surface protrusion. A portion of replicate glove damage. the snagged yarn is damaged (severed) as the fabric is pulled Results: Three damage modes were identified, which away from the surface.

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Space Operations

(Above) On orbit, the solar array mast extends, retracts, and provides structural support for the solar array panels.

(Left) Mathew Stegman (left) from JPL, Justin Templeton (center), and Dr. Kenny Elliott (on ladder) from LaRC set up the ISS solar array mast in JPL’s 25-foot-diameter Space Simulator Facility. The mast was subjected to the extreme temperatures of space to investigate the conditions that cause mast buckling.

Reproduction of ISS Solar Array Mast Shadowing Problem: Partial shadowing of the 108-foot-long support However, it was observed that this partial shadowing thermal masts on the International Space Station (ISS) solar arrays condition was not tested in the mast’s original development can occur. This induces differential heating between the or qualification process. As a result the NESC is conducting sunlit and the shadowed portions of the mast structure. The a ground test program to provide the best possible thermal resulting thermal strains are predicted to buckle the mast in and structural response data for correlation of the mast as little as 30 minutes. The condition was not considered models. The NESC contracted with the mast manufacturer in the original design of the mast. The 30 minute maximum to design and fabricate a special instrumented mast test exposure time has added complexity to controlling the solar section that was exposed to a simulated space vacuum arrays to avoid failure and raised concerns if attitude control and solar environment in the JPL’s 25-foot diameter Space were lost for any considerable period of time. ISS program Simulator facility. The mast was tested in October 2008. management requested the NESC conduct an independent Results: Preliminary test data are being examined. Final assessment of the thermal and structural analyses predicting test data will be correlated into thermal and structural models the failure and its time to effect. of the solar array masts. Predictions of the mast buckling NESC Contribution: The NESC conducted an initial failure load under the partial shadowing condition will be assessment of the analyses and did not find any modeling or updated. The NESC will work with the ISS Structures and analysis assumptions or techniques that could be improved Mechanisms team to recommend appropriate constraints to gain more margin and lengthen the time to mast buckling. for on-orbit operations.

Solving the Agency’s toughest problems: The NESC model of assembling a team of discipline experts from different NASA centers and companies enables solutions to problems otherwise not solvable. — Don Shockey, Director SRI International Center for Fracture Physics, Materials TDT NASA and its extended family in Government, Industry and Academia represent the most powerful engineering resource in the world. — Paul M. Munafo, Chief Engineer, Teledyne Brown Engineering, Materials TDT 3230 Port side truss segments showing solar array components. Center Focus

Computer image of Vehicle Assembly Building fire scenario. Center Focus

Dr. Tina Panontin NESC’s Chief Ames Research Center Engineer at ARC

uring 2008, Ames Research Center (ARC) continued to Dprovide a wide variety of expertise to NESC activities. Over 50 ARC civil servants and contractors provided support to the NESC’s Technical Discipline Teams and technical assessments. ARC provided experts in disciplines ranging from human factors, data mining, and computational modeling to composites, aeroacoustics, and nondestructive evaluation testing. The NASA Technical Fellow for human factors, Dr. Cynthia Null, is resident at ARC.

Exploration Systems Composite Crew Module (CCM): ARC personnel are a key part of the NESC’s CCM team, leading the design of the lower primary structure. The innovative design, in which the floor beams carry pressure load instead of the traditional ring frame and dome, has yielded a 100 lbs. mass savings. A variation of the load sharing backbone has been adopted by the Orion Project. An additional 50 lbs. mass savings was Results from the OVERFLOW simulation tool show instantaneous particle realized by shaping the shell into lobes which was easily traces colored by temperature in a VAB fire scenario. accomplished with composites. ARC personnel performed analysis of test components and assisted in the composite the probability of the solid rocket boosters in any of the other fabrication at ATK Iuka. Most of the three bays igniting, then identify the maximum possible heat lower structure is bonded with flux generated in the worst-case scenario and the resulting woven preform technology effects on nearby structures at KSC. developed by Lockheed Max Launch Abort System (MLAS): The USM3D flow Martin. A new structural solver is generating MLAS aerodynamic data that cannot be element was needed readily generated experimentally. ARC engineers improved at two intersections USM3D, focusing on increased performance and support along the main beams, for larger problem sizes. As a result, run time has been but existing preform reduced by 5 times, and memory requirements have been technology was not reduced by 2 times. Simulations that took a week now take mature. Titanium a day. ARC engineers are also incorporating visualization fittings were designed capabilities into the USM3D code that will allow the user to as back-ups while view the progress of computations on their desktop. composite preforms could be developed. Lower section of the 12- foot CCM Pressure Vessel Fittings were fabricated and shipped to ATK Iuka for assembly into test specimens. Pi preform shear strength tests will be performed at Ames in late 2008. Vehicle Assembly Building (VAB) Analysis: To support upcoming space exploration missions, modeling and simulation experts are providing a computational framework for simulating elements of the ground operations of future launch vehicles at KSC. Part of this NESC-sponsored effort is determining whether the VAB at KSC, used for the Space Shuttle, is properly equipped to safely handle the storage of significantly more fuel required for the Agency’s next- generation Ares I and Ares V vehicles. ARC experts are developing the capability to employ high fidelity CFD tools (OVERFLOW and Cart3D) to predict the effects of various fire scenarios in the VAB. The modeling will help determine USM3D flow solution of the MLAS at a subsonic flight condition.

SEE ALSO: MLAS, Page 14 44 Center Focus

Dr. Nancy J. Currie NESC’s Chief White Sands Test Facility Engineer at JSC

hite Sands Test Facility (WSTF) scientists and Wengineers have assisted the NESC in addressing important issues in NASA programs and projects. This year, testing and analysis centered on hypervelocity impacts, chemical oxygen generators, Composite Overwrapped Pressure Vessels (COPVs), technology requirements for the High Pressure Oxygen Generator Assemblies, pyrovalve failures, and a proposed method for treating hydrazine and monomethylhydrazine.

Space Operations A chemical oxygen generator explosion aboard a UK Royal Navy (RN) submarine resulted in crew fatalities and extensive damage. Since similar chemical oxygen generators provide backup oxygen on the International Space Station (ISS), the NESC sponsored a cooperative agreement for scientists and engineers from NASA and RN to work together to conduct a root cause analysis, chemical modeling, laboratory analysis, and field testing that resulted in a series of full-scale tests at Ben Gonzalez, GeoControl Systems Inc., and Brooks Wolle, Jacobs WSTF. The findings have increased fundamental knowledge Technology Inc., perform radiograph inspection of COPV weld anomalies of the mechanisms of chemical oxygen production and have at WSTF. led to operational changes and improved safety onboard RN submarines. Chris Keddy, Jacobs A project focusing on research and development of the Technology Inc., veri- technology required for a High Pressure Oxygen Generator fies measurements on a Assembly (HPOGA) was started this year. The HPOGA sectioned COPV against is a high differential pressure water electrolysis cell stack a structural model gen- that uses water to produce oxygen gas at up to 3000 psi erated in GENOA, a virtual testing and analysis without the need for a mechanical compressor. The oxygen software. tanks on the ISS are currently resupplied with high pressure gaseous oxygen by using space shuttle oxygen. When the Space Shuttle is retired the HPOGA is being explored as one option to meet ISS oxygen needs. Personnel from WSTF, Hamilton Sundstrand, and JSC are performing testing on vulnerability and shielding requirements. WSTF personnel HPOGA simulators. continued to assist the NESC assessment into ground test failures of pyrotechnically operated valves that are used in WSTF supported an NESC evaluation of a proposed numerous NASA spacecraft. A novel approach to analysis method for treating hydrazine and monomethylhydrazine- of the heat transfer mechanisms inside the pyrovalve primer contaminated equipment with alpha-ketoglutaric acid chamber assemblies was performed using a combination (AKGA). The tests were prompted by suggested cost and of computer analysis and test data. Recommendations for operational benefits to NASA for flight hardware and ground reliable operations were shared with NASA projects and support equipment decontamination, treatment of liquid programs such as the Solar Dynamics Observatory, Mars waste, spill remediation, and possibly vapor control. The Science Laboratory, Phoenix Mars Lander, and Orion. NESC and WSTF developed a quick-response team with Dr. Thomas Giordano from CH2MHILL to further examine the General treatment processes proposed by CH2MHILL. WSTF has supported the NESC Composite Pressure Vessel Working Group (CPVWG) in evaluating the effectiveness Science of nondestructive evaluation techniques for detection of Cables on the James Webb Space Telescope will be directly manufacturing flaws and vessel aging indications and exposed to micrometeoroid impact in the Earth-Moon L2 applied Raman spectroscopy for measurement of strain environment. WSTF’s Remote Hypervelocity Test Facility condition. WSTF has also developed a library of material conducted hypervelocity impact testing, some at cryogenic properties and stress rupture data on carbon and Kevlar temperatures, to support the NESC assessment of cable fiber materials.

SEE ALSO: JWST electrical cables, Page 23 45 Featured Technical Paper

Astronaut John Young, Apollo X command module pilot, participates in simulation activity in the Apollo Mission Simulator at the Kennedy Space Center.

Risk-Driven Design Approach for CEV Electrical systems enable the crew and ground to control critical spacecraft functions. Balancing competing needs and requirements, infusing new technology, and meeting tight mass and power constraints argues for a top down risk informed design approach to achieve an optimized system. – Michael Bay, Bay Engineering 4446 Featured Technical Paper

Iterative Risk Driven Design Approach for CEV Avionics Michael Bay, NASA Engineering and Safety Center (NESC) Avionics Technical Discipline Team, BEI Mitchell Davis, NESC Avionics Technical Fellow, NASA Blake Putney, Principal Risk Analyst, Valador

Abstract - An agency wide team led by the NASA Engineering and Safety Center (NESC) utilized an iterative, risk informed, build up design approach to decide where to apply mass resources to balance safety, performance, and affordability for Crew Exploration Vehicle (CEV) Avionics. The buildup approach started from a simple single string architecture to assure the solution was in the box, then identified weaknesses and risks to safety and mission success, considered operational alternatives to eliminate risks as well as the addition of backup systems and redundancy to restore adequate failure tolerance. The fundamental objective of the build up approach was to find the safest, most reliable and affordable system design by applying mass, power and other resources where they do the most good for safety and mission success.

TABLE OF CONTENTS starting point and was allowed the latitude to

1. TEAM CHARTER ...... 1 perform trade and design studies outside of the 2. BACKGROUND AND CHALLENGES ...... 1 current baseline and to challenge the existing 3. ASSEMBLING AN INTEGRATED TEAM ...... 4 requirements if necessary. Several challenges 4. DESCRIPTION OF THE DESIGN APPROACH...... 6 guided the study effort: 5. CONCLUSION ...... 14 Mass Constraints. The Lunar mission design 1. TEAM CHARTER poses severe mass constraints on the Crew An agency-wide team led by the NASA Exploration Vehicle as do most missions to Engineering and Safety Center (NESC) the Moon, Mars and elsewhere beyond LEO. participated in a study chartered to assess The physics of traveling to the Moon and driving requirements and consider alternative Mars involves the “pushing” of mass to the 1 designs for the CEV that may reduce mass. destination requiring significant propellant The Smart Buyer Team was challenged to and supporting structure. Power systems assess driving requirements and offer introduce a multiplicative effect on mass as alternative approaches to reduce mass without power must be collected, stored, distributed adversely effecting safety and mission and then shed as waste heat by the thermal success. One of the tasks involved a study of system. These multiplicative factors argue for the Avionics configuration for the CEV with the judicious control of power to allow the the express purpose of identifying safety, application of scarce mass resources where reliability, and mass drivers, and identifying they do the most good. how the avionics configuration effects vehicle mass. In addition the team was to identify the Reducing Mass. The CEV design had requirements that drove vehicle mass and how proceeded through several design cycles. The changes to those requirements may allow link between mission objectives and the mass reductions. To search for innovative required functions were masked by a large solutions, the Smart Buyer Team united number of lower level derived requirements technical expertise and experience of the including the application of two failure human spaceflight, robotic and research tolerance at a low level. The conceptual centers. design had matured to the point that a significant number of derived requirements 2. BACKGROUND AND CHALLENGES severely limited design options. The system was constrained to the point that alternative The CEV Smart Buyer Design Team (SBT) designs, even ones utilizing less mass, used the existing CEV design products as a appeared to violate derived requirements.

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Even after setting aside some derived requirements, the team found it hard to identify where to reduce mass and was not comfortable with “loping” off pieces of an existing system design without understanding how mass reductions would effect crew safety and mission success. The team was challenged to identify how to get the system back inside “the box”. Figure 1 shows a notional box with Risk, Performance, and Cost / Schedule boundaries. Valid solutions appear as surfaces inside the box boundaries. If a system design results in parameters outside the box, it is hard to lop off pieces to get back inside the box without compromising the integrity and cohesiveness of the integrated system. To avoid the drawbacks of loping pieces off Figure 1 Box Defining Boundaries the system, the study team started with a minimal system whose performance and cost and should be done about it. Decisions are parameters were well inside the box, and risk captured in procedures and flight rules and are parameters outside the box. The team then followed in a disciplined manner. During proceeded to build up the system, add to the operations, procedures and rules tend to drive minimal system reducing risk along the way what is done which is the opposite from until a balanced closed solution was found. upfront work where mission objectives, an operational sequence, and critical functions Design Prescriptions and Rules. While drive design. evaluating alternatives, the team recognized that there is no predefined recipe or Absent a prescription for a safe design, the prescription for safety. There is no a priori challenge then is to design the system for the prescription for the design of a safe human minimum risk at the integrated mission level. rated system. No single process or single rule Exploring alternate architectures along with such as two failure tolerance will by itself their associated failure modes is critical to assure safety and mission success. Hazards identifying the lowest risk and most robust exist in context of a design and an operational solution. Upfront design work provides the sequence and therefore are unique to each most leverage in obviating or mitigating mission. When considering safety as the weakness and should result in an architecture absence of uncontrolled hazards, we realize with a predictable and coordinated response to that we cannot write enough rules and failures threatening the critical functions requirements to preclude hazards and prevent necessary for safe crew return. A flexible latent defects. We cannot prove this iterative design loop is necessary to explore "negative", i.e. that all hazards are controlled, alternate designs and alternate operational or that there are no latent defects. approaches. Success during mission operations is assured Success in the high risk business of manned by following procedures and rules. Procedure space flight is grounded in providing and rule development starts by exploring and sufficient capabilities for “safe crew return” anticipating what may go wrong and what can should system elements fail. Teams need to

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explore system weaknesses, risks, hazards, other prescriptions can lead to the false etc, in context of the design’s operation and its confidence that compliance with those rules exposure to the natural and induced will result in a safe and proper system. The environments. An essential part of the risk sheer volume of rules / requirements and the evaluation includes identifying specific massive effort to show compliance with those functional failure modes of system elements. rules can lead to the illusion that the system When unacceptable threats are identified, must be a good and safe one. The irony of all ideally eliminate them from the design first the rules and prescriptions is they can and if that is not possible reduce the severity inadvertently reduce the discussions and of the threats by decoupling the threats from exploration on the very risks that the rules the susceptible system. Finally, design the seek to prevent, and can unintentionally susceptible system to tolerate the threats with remove the onus for a safe and reliable system the minimal impact or essentially survive the from the designers and place it on the rule consequences of the threat. writers. Top down and bottoms approaches are needed It was therefore important to distinguish to explore and capture system weaknesses between requirements establishing program with an objective of finding safer alternates needs and objectives from derived and or simple systems to preserve safe crew requirements intended to constraint the return. Not providing two failure tolerance, or solution space. The team identified the not meeting a requirement is not necessarily a requirements establishing needs and weakness of the system. Weaknesses exist in objectives that if met make the program actual physical vulnerabilities of the end item worthwhile. These served as the validation rooted in the as built system acting in a bases for subordinate derived requirements. manner that results in undesired The derived requirements were candidates for consequences. change and could be solidified later after a design reference mission and a design Two failure tolerance provides one approach has been considered and evaluated mechanism to minimize risk but such an from a risk standpoint. approach must be balanced against the added complexity and the utilization of scarce Safety and Mission Success. For the purposes resources. Additional complexity intended to of the study, a distinction was made between enable a system to survive a failure may result Safety (loss of crew) and Reliability (mission in a higher likelihood of system failures success). This distinction was important since offsetting the improved failure tolerance. a human rated vehicle fundamentally preserves safe crew return over mission Resources need to be applied where they do success. Safety and reliability objectives often the most good for the total system. Once work together, but can also compete. The two resources are consumed they cannot be used in work together when margins are added to the other areas to improve their safety. Stated system to ensure its continued operation from differently, a two failure tolerant system both safety and mission success perspectives. design should not result in a less safe system They compete when safety objectives seek to over other alternatives. prevent a hazardous condition that also Requirements. The team operated under the interrupts mission success. For example, a assumption that requirements can human rated system would set safety limits inadvertently constrain the design and prior to the point of failure to allow a crew potentially eliminate safer or lighter options. abort scenario. An early or false abort may A proliferation of requirements, rules, and occur at the expense of mission success. Such

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limits preserving abort are not present in decentralized to limit the coupling and the unmanned vehicles. cascading of failures from one subsystem into others and to allow the crew to utilize backup Complexity. Complexity is often the antithesis systems and simple manual methods to control of safety and reliability as complexity can critical vehicle functions. obscure unintended and unexpected interactions and coupling of system elements.2 3. ASSEMBLING AN INTEGRATED TEAM Robustness is achieved by knowledge of how The study effort expanded the term the system responds to intended actions or “Avionics” to the more global “Electrical faults and complexity obscures the Systems”. The electrical systems team predictability of the system’s response. A included representatives of all subsystem robust system is predictable, and does not elements that control the flow of electrons as produce surprises. A complex system with a well as software, mission design, and large array of interactions and stimuli will operations. The electrical system was defined harbor unexpected and undesirable responses. to include all electronics components on the Interactive complexity threatens to obscure spacecraft, from where the current or voltage safety risks. The system can become so is generated in a sensor or a power source to complex that there are “no obvious” safety where the current or voltage ends in an risks. Complexity should therefore be limited actuator, or the signals leave the spacecraft. to the minimum necessary to accomplish the This broad view enabled a holistic mission objectives. understanding of the complete system and rapid appreciation and evaluation of risk and Complexity is a relative term as no alternatives. meaningful absolute scale exists. Complexity must be linked to the ability to predict the The team also included Reliability, Safety and systems’ response and is not necessarily Risk analysts who provided a skeptical “what related to part count. Finding the correct level can go wrong” mindset complementing the of complexity is the hard part and requires engineer’s optimism in expecting the design to good systems engineering. To determine the work. minimum complexity the team established a The electrical systems team included minimal floor for the system design as driven representatives from Electrical Power, by the critical functions necessary for meeting Command & Data Handling, Communications mission objectives. & Tracking, Guidance Navigation & Control, A large part of the systems engineering effort and Software disciplines as shown in Figure 2. involved identifying where separate pieces For the crew interface, Environmental Control were necessary to support critical functions, And Life Support System & thermal, a clearly where they should be separated and defined interface was established to the decoupled, and then integrating those pieces electrical systems allowing independent into a cohesive whole. evaluation of the non-electrical systems. A driving consideration in minimizing the Representatives of the electrical systems team complexity of space systems design involves worked closely with the Systems Engineering balancing centralized versus distributed and Integration to coordinate issues that architectures with respect to safety. Due to crossed discipline boundaries. complexity, systems are centralized so a single The electrical system team’s study efforts element can orchestrate the integrated vehicle. relied heavily on a risk driven cyclic loop to However from a failure standpoint systems are attack risk drivers in a systematic top down

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coordinated electrical systems design team was guided by the following objectives: • Establish an integrated view of electrical components, sensors to actuators • Identify where common designs reduce box count and complexity • Identify where common cause failure threatens safety and reliability • Identify design overlaps and holes in design • Provide a clear and integrated interface to Safety and Reliability Analyses • Integrate results with the overall vehicle systems engineering team Figure 2 Electrical Systems Team Members Safety and reliability analysts were also part fashion as shown in Figure 3 and described in of the team providing a “skeptical” view and the rest of this paper. seeking to continually encourage “what can go wrong” type questions along with analyzing Each functional element of the electrical the system design. A key contribution of the system was assigned to a team member and reliability team is the linkage of the design team members were encouraged to reference mission to the design, to identify communicate and collaborate to ensure system level failure and recovery scenarios individual system elements combine into a that are used to evaluate back up redundancy cohesive integrated system. Functions and alternatives. This helps designers to envision interfaces were established with minimal the role of their system in its entire context overlap and without holes. The well- beyond the written requirement, allowing

Figure 3 Electrical Systems Risk Driven Design Loop

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them to conceive of designs that achieve high complexity of redundancy. The addition of reliability with maximum simplicity. backups, redundancy, and failure tolerance was addressed later after assessing weaknesses 4. DESCRIPTION OF THE DESIGN APPROACH and risks of the single string system. WITH EXAMPLE A secondary objective of establishing a A buildup approach was fundamental to the 3,4 minimalist system was to make sure the performance of the study. The approach simplest solution is in the box, if it is not, then started with the minimal incarnation of the alternate designs or even alternate mission system to: objectives and constraints maybe necessary. If a. provide rationale for the system design the minimalist system is in the box, then including efficient utilization of scarce margin to box limits were available to mass and power resources, improve safety and mission success based on b. identify whether the system has any risk drivers. hope if being “in the box”, c. establish a “floor” for the complexity Figure 4 shows the systems engineering of the system. approach starting with mission needs and objectives driving the identification of an In this case the minimal system was single operational sequence and critical functions string. Building up the system from this that in turn then drive an iterative design loop. baseline provides rationale for every system element, every watt, and every kilogram of An iterative design loop was necessary to mass based on system weaknesses and risk. assure the requirements, the system design, The single string system provides a direct link and the design reference operations concept between the required functions and mission are developed in a cohesive manner performance requirements without the assuring consistency.

Figure 4 Systems Engineering Approach

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Identify high level driving requirements. The elements whose failure response is study started with the identification of those inconsistent with the system’s critical requirements that establish program needs and functions. objectives as distinguished from derived The following considerations were important requirements that specify solutions. Due to the for the configuration of the single string overall goal of reducing mass, the team had design and balancing a distributed versus the flexibility to question requirements and centralized approach: identify those that if changed would result in mass savings. Network for Internal Communications – drivers were reliability (the simplest, lowest Capture the concept of operations in a design data rate necessary), low power, robust to reference mission. Understanding the failures (fail high, low, blabber mouth), along operational sequence as captured in the design with upgradeability and extensibility. Limiting reference mission was critical for the bus data rates below the 100 – 200 MBbs subsequent work. The time ordered sequence range minimizes power consumption and of activities necessary to meet mission dissipation at all the network nodes. objectives, their time criticality, and Additionally, limiting these rates significantly sequencing constraints became design drivers. reduces the complexity of testing the system. Identify Critical Functions. The time ordered Any interfaces requiring higher data rates sequence of activities helped define not only were hardwired point to point as necessary. the critical functions necessary for Method for connecting to the network – accomplishing mission objectives but also the through a robust terminal with low power critical functions for safety returning the crew. interfaces that interface to the bus on the front Critical functions for both safety and mission 5 end and to the user at the back end through success were defined and tracked separately. digital, serial and analog input and output Safety critical and mission critical functions interfaces. were then used to identify the simplest design Computer System Architecture – A central capable of implementing the functions. During computer was chosen to orchestrate functions the risk analysis described below, alternative performed by network terminals while approaches including back ups were identified balancing central control and limiting to protect these critical functions. coupling and interactions should terminals 4.1 Identify the simplest design of the system, fail. The design solution assigned safety “Make it Work”.6 For the purposes of this critical functions to appropriate terminals, Bus study the system was reduced to the simplest Interface Units (BIU,) and subsystem system that performs the critical functions electronics boxes. The BIU design would necessary to accomplish the mission provide predictable end item functionality in objectives. In this case a single string system the event of communication loss with the main with one computer was selected. It was computer, thus increasing the independence recognized that such a simple system would (robustness) of the subsystems. Additional not be “flyable”. However establishing a computational power necessary for Automated minimal system was critical for establishing a Rendezvous and Docking was provided by an floor for the minimum complexity of the Auxiliary computer that can be added as part system and determining whether a solution of a mission kit when needed along with existed within box boundaries. Starting with a sensors. simple system also serves to identify the system’s weakest links as well as those

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Figure 5 Integrated Risk Analysis Flow

Separation of Functions – Care was exercised the system design, the physics applicable for to limit the coupling of disparate functions. A the situation, and safety and reliability driving consideration for isolating functions analysis results as shown in Figure 5. Event was to limit collateral damage in the presence Sequence Diagrams were used as the of failures and to allow simple backup control mechanism for capturing specific scenarios of only the function that failed. The central and the resulting effects of failures. Failure computer was not given control over low level Modes and Effects Analysis (FMEA) were functions, rather the BIU defaulted to a performed from a top down functional predictable and known operational mode that standpoint as actual design details were not maintained low level functionality. Balancing yet complete. Historical failure rates were centralized control with distributing low level used for bottoms up reliability analysis to functions allows simple backup or manual represent the general likelihood of the type of controls to only replicate the failed higher system component and as a representation for level function. the complexity of the design. Engineering fears and threats based on historical data and 4.2 Explore risks to safety, and then “Make it engineering judgment were also used to Safe”. This step in the buildup approach was evaluate weaknesses of the simple system. designed to identify aspects of the design that Critical to this process was the collection and protects safety critical functions necessary to ranking of all risks from all sources. This meet mission objectives. The set of safety sorting and ranking part of the process is critical functions identified in the previous critical for systematically considering and steps were used to guide safety risk attacking the biggest risk drivers first. assessments. Risk assessments evaluated the basic single string design along with candidate As risk drivers are attacked, alternative design approaches seeking to obviate or approaches to the operations sequence and or mitigate risk through alternatives that the design were fed back into the loop for eliminate the risk, utilize system elements reevaluation. already on-orbit in different ways, point It is important to note that this type of analysis design solutions such as backups, or additional performed early in the project’s life cycle like redundancy. focuses more on a functional level than on a Integrated risk analysis. An integrated risk hardware level. It was too early in the program analysis brought together the operations to rely on "bottoms up" reliability analysis sequence from the design reference mission, alone. Without an actual design that would

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exist at CDR time, it is difficult to identify all around any predictive analysis. So the team the physical failures that can result in loss of needs to be careful when relying on failure crew. As the design matures specific failure rate estimates beyond the first significant modes of the exact design will replace figure. Thus the analysis provided the means functional failure modes. to rank the different architectures relative to each other without focusing on the absolute Component based models that only assume failure prediction of any given architecture. At hard failures may overlook important system this point the objective of the numbers is to failures that surface when individual help in the ranking and sorting of risks from components and software interact in all sources. unforeseen and adverse ways. The more complex the system becomes, the harder it is The risk analysis started with the end of the to anticipate all the ways it can fail especially mission, safe crew return, and sequenced this early in the design. It is for this reason backwards to launch. Four critical mission that it is advantageous to look for the simplest phases were evaluated “Entry, Descent, and most robust and easiest to understand solution Landing”, “Critical Burn”, “Lunar Loiter”, that attacks each weakness and preserves and “Ascent” and captured in event sequence critical functions. The team identified what diagrams. Figure 6 provides an example of the functions might fail so that the system can type and format of the Event Sequence protect those functions. Diagrams that were created for each of the critical mission phases. The event sequence The team also recognized that there are diagram helped to visualize the responses and significant error bars, up to a factor of 10,

Figure 6 Example of the Event Sequence Diagram

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downmodes that could protect the crew. The a) a simple manual control while crewed, iterative risk analysis loop, shown in Figure 5, b) a simple “safemode” to protect a power along with the event sequence diagrams, positive and stable vehicle attitude while Figure 6, allowed an exploration of risk along uncrewed, and the operational sequence and an evaluation of c) a low power mode to enable an Apollo 13 alternatives that eliminate the risk, designs style manual, minimal power return. that inherently should not fail, utilize system It is significant to note that the first elements elements already in orbit in different ways, added to the minimal single string vehicle

point design solutions, or redundancy. were not additional strings of like full Exploring alternatives for mitigating each risk performance redundancy. The team sought to was critical and requires creative add simple diverse systems for manual control "engineering" and compromise among often while crewed and simple safemode while competing needs. The team looked for the uncrewed to protect safe crew return at most mass efficient method to reduce risk. reduced, but adequate performance. Figure 7 Some alternatives mitigate more than one risk, provides a functional diagram for the and finding these synergistic solutions Safemode and Manual System. Manual attacking multiple risks was important. The control or providing simpler systems to team looked at all the risk on the table and let control actuators is utilized on modern aircraft the risks drive solutions and design decisions. such as the 777. Simple systems or “safemodes” protecting health and safety are The integrating risk analysis identified major often utilized on unmanned spacecraft to drivers that resulted in the following three provide time and opportunity for the ground to additions to the simple single string system: apply appropriate corrective action.

Figure 7 Safehold and Manual System Functional Diagram

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An uncrewed safemode also provides a last return of the crew using simple low power line of defense, a “never give up” function systems even under an Apollo 13 type or ISS preserving the vehicle health and safety Computer Loss scenario after primary systems should the primary system fail. Safemode suffer unexpected failures. provides a power and thermal safe attitude as Safety improvements to power generation and well as a stable attitude for Lunar Ascent distribution systems considered the coupling Module Docking using simple coarse sensors between power and data functions to assure and a gyro controlled by a simple hardware that failures in the power strings minimize based controller. collateral damage, i.e. coupling, to other Safemode was focused on assuring crew subsystems. For example, power and data safety through robustness enabled by an paths were defined such that failures in a data alternate means to control critical vehicle path would not couple into power distribution systems. This independent system becomes and failures in power generation and storage even more powerful from a reliability would limit the effects on data paths. For perspective if it remains simple containing example, failure of a power feed switch results fewer parts and fewer connections. The simple in loss of the load’s function and needs to be safemode is lower performance than the prime tracked that way. Safety critical functions system, although it has the requisite were protected from switch failures by diverse performance to enable safe crew return. or alternate power feeds. The Safemode and Simplicity in the dissimilar system can also manual control function was given a significantly mitigate the cost burden of separately powered safemode and emergency having to design, certify and maintain full power bus with its own emergency battery. performance “backup” systems. The goal is to Uncrewed operation also required a certain achieve a significant improvement in overall number for “special” hardware decoded reliability for a fraction of the cost of the commands that enable reset, recovery, and primary system. Simple systems are more reconfiguration of the primary system without easily manufactured and tested due to their requiring the primary system to do so. The lower complexity and are more reliable due to team provided recovery methods such that fewer failure modes and better test coverage. prime system failures do not prevent Safemode provided a Sun Pointing Mode, an utilization of redundant and safemode Attitude Hold Mode and worked in systems. conjunction with manual crew control. In The team utilized a litmus test for assessing addition, some critical subsystems such as the “independence” of prime system elements power and ECLSS had enough local "smarts" from the systems protecting the capability to in the BIU to control battery charging, load safely return the crew. The test involves shedding, and control of the breathable air and encircling system elements on a system block temperature autonomously. Communications diagram that are necessary for crew return with the ground are via 4 pi Omni antennas using the prime system and then encircling that did not require any onboard switching elements necessary for safemode. Any logic to achieve a minimally functioning overlaps, or circling of common elements forward and return link. between the prime system and the safemode With the safemode added to the system, system warns the system designer of the failure of the central computer or its network potential for common cause failures that need had minimal immediate effect on system to be addressed. health and safety. The vehicle can enable safe

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Author’s addendum as of 12/9/08 Subsequent research and study of space flight failures indicates significantly lower mission ending common cause failure probabilities than the references suggest. FigureFigure 8 Conditional8 Conditional Probabilities Probabilities of ofMultiple Multiple Failures Failures in inIdentical Identical Components Components Figure 8 Conditional Probabilities of Multiple Failures in Identical Components Risk Analysis Results. Reliability analysis other non-aerospace sources (see references Risk Analysis Results. Reliability analysis other non-aerospace sources (see references supportedsupportedRisk Analysis the the integrated integrated Results. risk risk Reliability assessments assessments analysis by by FigureFigureother 8 ) non 8that) that-aerospa do do offer offerce insights sources insights particularly (seeparticularly references for for providingprovidingsupported failu failu there re integratedrate rate estimates estimates risk that assessments that were were used used by secondsecondFigure string 8string) that failures. failures.do offer As insightsAs shown shown particularlyin inthe the green green for to toproviding rank rank risk risk failu drivers. drivers.re rate To estimates To thoroughly thoroughly that evaluatewere evaluate used blockblocksecond a rangea string range wasfailures. was determined determined As shown from from in eachthe each green of of failurefailureto rank likelihood, likelihood, risk drivers. two two "knobs" To "knobs" thoroughly were were applied evaluate applied thesetheseblock sources sources a range which which was are determinedare all all in inrelatively relatively from eachgood good of to tofailure the the likelihood, reliability reliability two models, models, "knobs" one one were is isapplied the the agreementagreementthese sources to toestimate estimatewhich aare rangea allrange in for relativelyfor the the secon secon goodd d "statistically"statisticallyto the reliability independent" independent" models, or or random random one failure is failure the stringstringagreement avionics avionics to failures. estimate failures. a range for the second rate and the other is the "dependent" or rate"statistically and the independent" other is the or "dependent" random failure or ManyManystring alternatives avionics alternatives failures. were were evaluated evaluated during during the the correlatcorrelateded / "common / "common cause" cause" failure failure rate. rate. rate and the other is the "dependent" or coursecourseMany of alternatives of the the risk risk were analysis. analysis. evaluated Re Results duringsults are arethe SinceSincecorrelat systemed system / "common component component cause" selectionfailure selection rate. and and summarizedsummarizedcourse of in the in Figure Figure risk 9 analysis. 9providing providing Re a relativeasults relative are detaileddetailedSince design systemdesign remains remains component in influx, flux, failure selectionfailure rates rates of and of comparisoncomparisonsummarized of ofsingle in single Figure string string 9 to providing toquad quad redundant redundant a relative similarsimilardetailed hardware hardwaredesign remains elements elements in wereflux, were failure used used in rates in the the of systemssystemscomparison with with of common single common string cause cause to quad factors factors redundant and and analysis.analysis. Failure Failure rate rate sources sources included included componentcomponent failu failure re rate rate along along with with applied applied similar hardware elements were used in the systems with8 common cause factors and databasesdatabasesanalysis. of Failure of Shuttle, Shuttle, rate ISS, ISS, sources and and robotic included robotic uncertaintiesuncertaintiescomponent . 8 failu. Results Resultsre rate show show along that that with common common applied spacecraftspacecraftdatabases experience. experience. of Shuttle, ISS, and robotic causecauseuncertainties failures failures 8.tend Results tend to to limit show limit the the that reliability reliability common improvements above 2 or 3 strings. A sweet CommonCommonspacecraft cause e causexperience. failure failure probabilities probabilities and and improvementscause failures above tend 2to or limit 3 strings. the reliability A sweet spotspot is is evident evident somewhere somewhere around around 2 2strings strings uncertaintiesuncertaintiesCommon that cause that were were failure used used in probabilities in the the reliability reliability and improvements above 2 or 3 strings. A sweet 7 7 andand 3 3 strings strings with with a a diverse diverse safemode safemode analysisanalysisuncertainties are are shown shown that in were inFigure Figure used 8 . 8 inThe. The the lower lower reliability left left spot is evident somewhere around 2 strings 7 providingprovidingand 3 additiona strings additiona l with benefits.l benefits. a diverse From From a safemode asafety safety cornercorneranalysis includes includes are shown a notionala notional in Figure probability probability 8 . The thatlower that the leftthe andandproviding reliability reliability additiona standpoint standpointl benefits. the the team team From felt felt that a that safety an an firstfirstcorner string string includes will will fail. a fail. notional The The broad broadprobability bands bands abovethat above the optimizedoptimizedand reliability “sweet “sweet standpoint spot” spot” exists exists the in teamina 2a to2 felt to3 string 3that string an thethefirst first first string string string willfailure failure fail. probability Theprobability broad represent represent bands abovethe the primeprimeoptimized system system “sweet with with spot” a a diverse exists diverse in independent a independent2 to 3 string estimatesestimatesthe first for string for the the probabilityfailure probability probability of ofa seconda secondrepresent string string the safemodesafemodeprime system as as depicted depicted with in a in Figure diverse Figure 8 . 8 independentAdding. Adding a a failingfailingestimates given given for that thatthe the probabilitythe first first string string of has a has second failed, failed, stringthe the secondsecondsafemode prime prime as depicted string string in does Figure does significantly 8 significantly. Adding a probabilityprobabilityfailing given of ofa that thirda third the string firststring stringfailing failing has given givenfailed, that that the improveimprovesecond th primee th e system system string failure failure does rate rate significantly with with a a twotwoprobability strings strings have ofhave afailed, thirdfailed, andstring and the thefailing probability probability given ofthat of relativelyrelativelyimprove low th lowe contribution system contribution failure from from rate common common with a a fourthatwo fourth strings string string have failing failing failed, given given and that thethat three probability three strings strings of causecauserelatively failure failure low and and appears contribution appears mass mass from efficient efficient common for for havehavea fourth failed, failed, string respectively. respectively. failing given While While that therethree there havestrings have thethecause reliability reliability failure benefit. and benefit. appears Adding Adding mass more more efficient than than 3for 3 beenbeenhave no failed, no studies studies respectively. that that provide provide While definitive there definitive have stringsstringsthe reliabilityfor for the the purpose purpose benefit. of ofreducing Adding reducing the more the random random than 3 estimatesestimatesbeen no for for studies these these valuesthat values provide for for spacecraft spacecraft definitive portionportionstrings of for of the the the failurepurpose failure rate of rate reducing does does not the not appear random appear components,components,estimates forsome some these limi limi ted valuested studies studies for have have spacecraft been been necessanecessaportionry ry of and and the brings bringsfailure with withrate it does it a a significant not significant appear performedperformedcomponents, on on Space someSpace Shuttle limi Shuttleted components, studies components, have and beenand necessary and brings with it a significant performed on Space Shuttle components, and

12 12 12 58 Featured Technical Paper

common cause contribution that does not make it mass efficient. There are other reasons to add multiple strings as discussed later. These reasons include voting out failures under time critical scenarios. Figure 10 compares the failure contributors of a three string system, to a three string plus safemode, and a four string system. Examination of the figure shows that the safemode reduces the system failure Figure 9 Example Comparison of Alternatives vs. Probability of probability by half. Loss of Crew Improvement Including Uncertainty Failure modes that the safemode backs up essentially disappear (e.g. In general it appeared that two strings may Crew Interface Displays) due to the credit for provide sufficient reliability as indicated by independent backup, while the failure rate the results shown in Figure 8, however contribution of other system elements that are identifying which of the two strings has failed not protected by the safemode (e.g. S/A may be difficult. Most failures could probably Regulator) merely reduce. The benefit of be isolated by built in self tests or by adding a fourth string is limited relative to comparing inputs and / or outputs against adding a safemode by the potential for expected results. However the possibility of common cause failures. dilemma cases requires a tie breaker. Use of the diverse safemode may aid in breaking a 4.3 Explore risks to Mission Success, and tie, although safemode’s reduced performance then “Make it Reliable”. The set of mission may not provide sufficient precision and critical functions, as opposed to safety critical accuracy. Therefore a third string was added functions discussed in 4.2 above, were used to to resolve dilemma cases for time critical guide the exploration of threats to mission functions allowing a simpler voting scheme success. These threats were captured and among three strings. There was a mass penalty attacked from most significant to least for the third string, however modern low significant. Many threats to mission success power and low mass components alleviated surfaced during the safety discussions and some of the inefficiency. analyses described in the previous step and were addressed in this step. In general a second string of like redundancy was added to the prime system to improve the probability of mission success.

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4.4 Look at resources including development costs and then “Make it affordable”. Life cycle costs were factored into some of the decisions that were drivers. Cost drivers included nonrecurring software development as well as maintenance. Drivers from a safety and reliability standpoint included Fault Detection, Isolation and Recovery (FIDR) and Integrated System Health Monitoring (ISHM). A major supporting driver included the consideration of additional redundancy to enable voting over more extensive FIDR and built in test. In general the addition of a third string simplified software Figure 10 Example Comparison of Electrical Systems development by enabling Element Contribution to PLOC voting algorithms.

5. CONCLUSION addition, some low power and low mass The Smart Buyer design effort was successful technology routinely utilized by robotic in identifying risk based design drivers, spacecraft can be transferred to manned recommending requirement changes along spacecraft. with innovative design alternatives that could • There are no a priori prescriptions taken by reduce mass while improving safety and themselves that result in a safe design, reliability. therefore the design team must design for • Merging of technical expertise and the minimum mission risk. Even a two experience of the human spaceflight, robotic failure tolerant design should not be chosen and research centers was effective in over a safer alternative. Minimizing risk identifying alternate concepts that reduce centers around exploring system weaknesses complexity, power and mass. In particular, and unpredictability in context of the techniques utilized by robotic spacecraft to operational scenario and then attacking keep the vehicle safe directly apply during those risks from highest to lowest. the operational phases where the CEV is • Designers must control complexity that may “uncrewed” in lunar orbit. Robotic obscure hazards and unintentional spacecraft experience complemented the interactions and coupling of system experience of the manned space flight elements. Teams should avoid complexity centers in utilizing the crew’s capabilities that results in “no obvious safety risks”. for enhancing mission success and safety. In Early design and analysis work should focus

60 Featured Technical Paper

on preserving critical functions and Julie Kramer White of NASA, (current CEV introducing complexity only where it is Chief Engineer,) NESC Discipline Expert in necessary for safety and mission success. Mechanical Analysis, Reliability Lead during the performance of the Smart Buyer Study and • An effective approach to defend against the initial NESC DDT&E Report team lead. interactive failures obscured by system complexity is through simple, easy to Dawn Schaible of NASA, NESC Systems understand diverse systems that protect Engineering Office Manager, for her role as those functions critical for safe crew return. the Systems Engineering Lead for the study. • It is important that teams identify and collect TK Mattingly, Rear Admiral, USN, Ret. Apollo risks in a systematic, top down fashion and 16 Command Module Pilot and Commander assure they remain visible and are of Shuttle Missions STS-4 and STS-51C, for communicated to team members. his wise advice and focus on simplicity and assuring safe crew return. • A “build up” approach is effective in limiting complexity to the minimum Agency wide Smart Buyer Study Team. necessary and providing a risk informed References: rationale for not only the system design, but 1 “Crew Exploration Vehicle ‘Smart Buyer’ also the rationale for the existence of every Design Team Final Report”, NASA component and the utilization of power and Engineering and Safety Center, May 2006 mass resources. The buildup approach 2 Discussions with TK Mattingly balances each risk in light of all the other 3 Build up approach from manned spaceflight risks present in the vehicle. Accepting risks experience suggested by TK Mattingly Apollo is also balanced against the utilization of 16 CM Pilot and Shuttle Mission Commander, power and mass resources and increased Jerry Gilmore based on Apollo Guidance complexity. System design at Draper Labs, Joseph Fragola Severe mass constraints require the wise based on Apollo LM design techniques at utilization of scarce mass resources to protect Grumman safety and mission success. Both the Crew 4 Build up approach from robotic spacecraft Exploration Vehicle and the Lunar Access experience: Bay, Michael, “MIDEX / MAP Surface Module projects are utilizing variants Project Reliability Program Overview”, Sept of the build up approach described above to 1997 not only design their vehicles but also balance 5 See “Safety and Mission Success” under risks. Additional information about this risk section 2. informed, systems engineering technique is 6 Description of the build up approach as available in the NESC Report RP-06-108_05- “make it work”, “make it safe”, and “make it 173, “Design, Development, Test, and affordable” from discussions with Joseph Evaluation (DDT&E) Considerations for Safe Fragola and Reliable Human Rated Spacecraft 7 “Design Development Test and Evaluation Systems, Volume I” May 1 2007, (DDT&E) Considerations for Safe and http://www.nasa.gov/pdf/176245main_RP-06- Reliable Human Rated Spacecraft Systems, 108_05-173_DDT%26E_Final_04-30- Volume I”, NESC RP-06-108_05-173, May 1 07_(Vol[1]._1Master).pdf 2007, Figure 3.4-1. 8 Adapted from data in “Crew Exploration Vehicle ‘Smart Buyer’ Design Team Final The authors would like to recognize and Report”, NESC, May 2006, Section 4.1. acknowledge the significant contribution of:

61 Tommy Yoder, Jacobs Technology at WSTF, places fiduciary markers on a large Kevlar® COPV being prepared for pressure testing.

PHOTO

Cross-Agency teaming: “In my experience as a NASA researcher, cross-Agency teaming occurred only when self-initiated by researchers. The NESC brought team members with unique expertise together from seven Centers. I was impressed by how effectively they all leaned on and learned from each other.” — Dr. Terry St. Clair, Consultant Team Member, Retired Materials Research Branch Manager, LaRC 6260

Leadership Core Team Biographies

NESC Core Leadership

Ralph R. Roe, Jr. NESC Director Dr. Daniel Winterhalter NESC Chief Scientist Mr. Ralph R. Roe, Jr. serves as NESC’s Direc- tor at Langley Research Center (LaRC). Mr. Roe Dr. Winterhalter is NESC’s Chief Scientist and is has over 25 years of experience in human space resident at the Jet Propulsion Laboratory (JPL). flight program management, technical manage- Dr. Winterhalter has over 30 years of experience ment, and test engineering. Mr. Roe previously held several key as a research scientist at JPL. His research interests include the positions in the Space Shuttle Program, including Vehicle Engi- spatial evolution of the solar wind into the outer reaches of the neering Manager, Launch Director, and Kennedy Space Center heliosphere, as well as its interaction with and influence on plan- Engineering Director. etary environments. In addition, as a member of several flight teams, he has been intimately involved with the planning, launch- ing, and operating of complex spacecraft and Timmy R. Wilson space science missions. NESC Deputy Director Mr. Timmy R. Wilson is NESC’s Deputy Director. Patricia L. Dunnington Mr. Wilson was formerly the NESC’s Chief Engi- Manager, Management and Technical neer at Kennedy Space Center (KSC). Prior to Support Office joining NESC, Mr. Wilson served as Deputy Chief Engineer for Shuttle Processing at KSC. Mr. Wilson has over 27 Ms. Patricia L. Dunnington is the Manager of years of engineering and management experience supporting the Management and Technical Support Office the Space Shuttle Program. at Langley Research Center (LaRC). Prior to joining NESC, Ms. Dunnington served as the Agency’s Chief Information Officer (CIO) at NASA Headquarters. Ms. Dunnington began her NASA Kenneth D. Cameron career in 1982 as a Presidential Management Intern. Ms. Dun- NESC Deputy Director for Safety nington has held several positions in the Agency, including the Mr. Kenneth D. Cameron is the acting NESC Deputy CIO and the CIO for the NASA Langley Research Center. Chief Astronaut and NESC’s Deputy Director for Safety and is resident at the Johnson Space Dawn M. Schaible Center (JSC). Mr. Cameron was formerly an Manager, Systems Engineering Office NESC Principal Engineer serving at Langley Research Center Ms. Dawn M. Schaible is Manager of NESC’s (LaRC). Mr. Cameron joined NESC after 7 years in private in- Systems Engineering Office at Langley Research dustry and a career in the U.S. Marine Corps. Mr. Cameron has Center (LaRC). Prior to joining NESC, Ms. Schai- over 28 years of experience in aeronautics and astronautics as ble worked in the International Space Station/ a Naval Aviator, Test Pilot, and Astronaut, and is the veteran of Payload Processing Directorate at Kennedy Space Center. Ms. three Space Shuttle missions: Pilot of STS-37 and Commander Schaible has over 21 years of experience in systems engineering, of STS-56 and STS-74. integration, and ground processing for the Space Shuttle and In- ternational Space Station Programs. Dr. Charles J. Camarda NESC Deputy Director for Advanced Projects Dr. Charles J. Camarda is the Deputy Director for Advanced Projects and is resident at the Johnson Space Center. Dr. Camarda began his NASA career in 1974 as a thermal structures research scientist at the Langley Research Center. He has over 34 years of technical and management experience in thermal structures and materials research for aircraft, spacecraft, and space launch vehicles. He was selected as an astronaut candidate in 1996, and flew aboard STS-114 as a Mission Specialist.

63 Biographies

NASA Headquarters Liaison NESC Principal Engineers Con’t. Wayne R. Frazier Michael T. Kirsch NASA Headquarters Senior SMA NESC Principal Engineer Integration Manager Mr. Michael T. Kirsch is a Principal Engineer with Mr. Wayne R. Frazier currently serves as Senior Safe- NESC at Langley Research Center (LaRC). Mr. ty and Mission Assurance Manager in the Office of Kirsch joined NESC from the NASA’s White Sands Safety and Mission Assurance (OSMA), where he is Test Facility (WSTF) where he served as the Deputy assigned as the Liaison Officer to NESC, the Office Manager responsible for planning and directing de- of the Chief Engineer, the Software Independent Verification and Vali- velopmental and operational tests of spacecraft propulsion systems dation Facility in West Virginia, and other remote activities of OSMA. and related subsystems. Mr. Kirsch has over 19 years of experience He was formerly Manager of System Safety in the OSMA at NASA in managing projects and test facilities. Headquarters and has over 33 years of experience in System Safety, Propulsion and Explosive Safety, Mishap Investigation, Range Safety, Pressure Systems, Crane Safety and Orbital Debris Mitigation. NESC Chief Engineers

NESC Principal Engineers Dr. Nancy J. Currie NESC Chief Engineer Clinton H. Cragg Dr. Nancy J. Currie is NESC’s Chief Engineer at Johnson Space Center (JSC). Dr. Currie came to the NESC Principal Engineer NESC from JSC, where she served as the Deputy Mr. Clinton H. Cragg is a Principal Engineer with Director of the Engineering Directorate. Dr. Currie NESC at Langley Research Center (LaRC). Mr. Cragg has over 20 years of expertise in robotics and human came to NESC after retiring from the U.S. Navy. Mr. factors engineering. Dr. Currie was selected as an astronaut in 1990, Cragg served as the Commanding Officer of the is a veteran of four space shuttle missions, and has accrued 1000 U.S.S. Ohio and later as the Chief of Current Opera- hours in space. tions, U.S. European Command. Mr. Cragg has over 30 years of experience in supervision, command, and ship-borne nuclear safety. Dennis B. Dillman NESC Chief Engineer Steven J. Gentz Mr. Dennis B. Dillman is NESC’s Chief Engineer at NESC Principal Engineer NASA Headquarters. Mr. Dillman came to NESC from the NASA Goddard Space Flight Center Mr. Steven J. Gentz is a Principal Engineer with (GSFC), where he chaired design reviews for major NESC at Langley Research Center (LaRC). Mr. Gentz projects, including the Hubble Space Telescope Ser- joined NESC from the Marshall Space Flight Center vicing Missions, the James Webb Space Telescope, and several Earth with over 25 years of experience involving numerous Observing System satellites. Prior to his time at GSFC, Mr. Dillman NASA, Department of Defense, and industry failure worked at the NASA Johnson Space Center managing Shuttle Orbiter analyses and incident investigations, including Challenger, Columbia, sustaining engineering efforts and training Shuttle flight crews. Tethered Satellite System, and the TWA 800 Accident Investigations. R. Lloyd Keith Dr. Michael G. Gilbert NESC Chief Engineer NESC Principal Engineer Mr. R. Lloyd Keith is NESC’s Chief Engineer, as well Dr. Michael G. Gilbert is a Principal Engineer with as the Deputy Center Chief Engineer at the Jet Pro- NESC at Langley Research Center (LaRC). Dr. Gil- pulsion Laboratory (JPL). Mr. Keith has over 31 years bert was formerly the NESC Chief Engineer at LaRC. of experience working in both technical and mana- Before joining NESC, he was Head of the LaRC gerial positions. Mr. Keith has supported a number Systems Management Office. Dr. Gilbert has over of flight projects including the Mars Pathfinder Project, SeaWinds, 30 years of engineering, research, and management experience with Stardust, Mars ’98, New Millennium Deep Space 1, and the Flight aircraft, missile, spacecraft, Space Shuttle, and International Space Hardware Logistics Program. Station Programs. Stephen A. Minute NESC Chief Engineer Mr. Stephen A. Minute is NESC’s Chief Engineer at Kennedy Space Center (KSC). Mr. Minute came to the NESC from KSC, where he served as the Chief of the Shuttle Safety, Quality, and Mission Assurance Division. Mr. Minute has over 24 years of engineering and management experience in the Space Shuttle and Interna- tional Space Station Programs.

64 Leadership Core Team Biographies

NESC Chief Engineers Con’t. NESC Chief Engineers Con’t. Dr. Tina L. Panontin Dr. James F. Stewart NESC Chief Engineer NESC Chief Engineer Dr. Tina L. Panontin is the NESC Chief Engineer at Dr. James F. Stewart is NESC’s Chief Engineer at Ames Research Center. Dr. Panontin also serves as Dryden Flight Research Center (DFRC). Dr. Stewart the ARC Chief Engineer and formerly served as the joined the NESC from DFRC where he served as the Chief of the Failure Analysis and Materials Group at Dryden Exploration Mission Director. Dr. Stewart ARC. Dr. Panontin has over 25 years of experience has over 42 years of management and technical experience leading in solving complex problems, assessing the health of systems and missile and aircraft programs. organizations, investigating anomalies and failures, and developing tools that support systems engineering processes. Clayton P. Turner NESC Chief Engineer Dr. Charles F. Schafer Mr. Clayton P. Turner is NESC’s Chief Engineer at NESC Chief Engineer the Langley Research Center (LaRC). Mr. Turner also serves as the LaRC Chief Engineer. He has Dr. Charles F. Schafer is NESC’s Chief Engineer at over 18 years of management and technical expe- Marshall Space Flight Center (MSFC). Dr. Schafer rience including serving as the technical/program- came to the NESC from MSFC where he served as matic lead for several projects including the Gas Permeable Polymer the Deputy Manager of the Propulsion Research Materials (GPPM) Project and the Gas and Aerosol Monitoring Sen- Center of the Science and Technology Director- sorcraft (GAMS) Project. ate. Dr. Schafer has over 42 years of experience in leading research and technology activities in advanced earth-to-orbit and in-space propulsion, including work in nuclear propulsion, plasma propulsion, advanced chemical propulsion, and new chemical propellents. NASA Technical Fellows

Steven S. Scott Michael L. Aguilar NESC Chief Engineer NASA Technical Fellow Mr. Steven S. Scott is NESC’s Chief Engineer at Mr. Michael L. Aguilar is the NASA Technical Fellow Goddard Space Flight Center (GSFC). Mr. Scott for Software and is resident at Goddard Space Flight also serves as the GSFC Chief Engineer. Mr. Scott Center (GSFC). Mr. Aguilar joined the NESC from formerly served as the NESC Discipline Expert (now GSFC where he served as the James Webb Space called NASA Technical Fellow) for Software. Mr. Telescope (JWST) Instrument Software Manager. Scott has over 18 years experience in satellite soft- Mr. Aguilar has over 32 years of experience on embedded software ware engineering. development.

Michael D. Smiles Mitchell L. Davis NESC Chief Engineer NASA Technical Fellow Mr. Michael D. Smiles is NESC’s acting Chief En- Mr. Mitchell L. Davis is the NASA Technical Fellow gineer at Stennis Space Center (SSC). Mr. Smiles for Avionics and is resident at the Goddard Space joined the NESC from SSC, where he served as the Flight Center (GSFC). Mr. Davis was the Chief Engi- Safety and Mission Assurance (S&MA) Manager. neer of the Electrical Systems Branch at GSFC prior Mr. Smiles has over 23 years of management and to joining the NESC. Mr. Davis has over 26 years of technical experience with NASA at SSC and Mar- experience in power and avionics. shall Space Flight Center. Cornelius J. Dennehy Bryan K. Smith NASA Technical Fellow NESC Chief Engineer Mr. Cornelius J. Dennehy is the NASA Technical Mr. Bryan K. Smith is NESC’s Chief Engineer at Fellow for Guidance Navigation and Control (GNC) Glenn Research Center (GRC). Mr. Smith joined the systems and is resident at Goddard Space Fight NESC from GRC where he served as Deputy Chief Center (GSFC). Mr. Dennehy came to NESC from of the Power and In-Space Propulsion Division and the Mission Engineering and Systems Analysis Division at GSFC, Chief of the Space Flight Project Office. Mr. Smith where he served as the Division’s Assistant Chief for Technology. Mr. has over 21 years of engineering and management Dennehy has over 28 years of experience in the architecture, design, experience leading the development of space flight systems. development, integration, and operation of GNC systems, and space platforms for communications, defense, remote sensing, and scientific mission applications.

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65 Biographies

NASA Technical Fellows Con’t. Roberto Garcia Dr. Robert S. Piascik NASA Technical Fellow NASA Technical Fellow Mr. Roberto Garcia is the NASA Technical Fellow Dr. Robert S. Piascik is the NASA Technical Fellow for Propulsion and is resident at Marshall Space for Materials and is resident at Langley Research Flight Center (MSFC). Mr. Garcia came to NESC Center (LaRC). Dr. Piascik joined NESC from the from the Solid Propulsion Systems Division where LaRC Mechanics of Materials Branch and the Met- he served as Division Chief. Mr. Garcia has over 17 years of ex- als and Thermal Structures Branch, where he served as a Senior perience in performing aerodynamic, hydrodynamic, and engine Materials Scientist. Dr. Piascik has over 24 years of experience in system design and analysis of rocket propulsion. the commercial nuclear power industry and over 16 years of experience in basic and applied materials research for several NASA Dr. Curtis E. Larsen programs. NASA Technical Fellow Dr. William H. Prosser Dr. Curtis E. Larsen is the NASA Technical Fellow NASA Technical Fellow for Loads and Dynamics and is resident at John- son Space Center (JSC). Prior to joining NESC, Dr. William H. Prosser is the NASA Technical Fel- Dr. Larsen was the Technical Discipline Manager low for Nondestructive Evaluation and is resident for Cargo Integration Structures in the Space Shuttle Program’s at Langley Research Center (LaRC). Dr. Prosser Flight Operations and Integration Office. Dr. Larsen has over joined the NESC from the Nondestructive Evalua- 28 years of engineering experience with expertise in stochastic tion Sciences Branch at LaRC. Dr. Prosser has over 21 years of structural dynamics, structural safety, and probabilistic engineer- experience in the field of ultrasonic and acoustic emission sensing ing applications. techniques.

Daniel G. Murri Dr. Ivatury S. Raju NASA Technical Fellow NASA Technical Fellow Mr. Daniel G. Murri is the NASA Technical Fellow Dr. Ivatury S. Raju is the NASA Technical Fellow for Flight Mechanics and is resident at Langley Re- for Structures and is resident at Langley Research search Center (LaRC). Mr. Murri served as Head of Center (LaRC). Dr. Raju was the Senior Technolo- the Flight Dynamics Branch at LaRC before joining gist in the LaRC Structures and Materials Compe- the NESC. He has over 27 years of engineering experience con- tency prior to joining the NESC. Dr. Raju has over 33 years of expe- ducting numerous wind-tunnel, simulation, flight-test, and theo- rience in structures, structural mechanics, and structural integrity. retical studies in the exploration of new technology concepts and in support of aircraft development programs. Henry A. Rotter NASA Technical Fellow Dr. Cynthia H. Null Mr. Henry (Hank) A. Rotter is the NASA Technical NASA Technical Fellow Fellow for Life Support/Active Thermal and is resi- Dr. Cynthia H. Null is the NASA Technical Fellow dent at Johnson Space Center (JSC). Mr. Rotter for Human Factors and is resident at Ames Re- joined the NESC from the JSC Crew and Thermal search Center (ARC). Before joining NESC, Dr. Systems Division and the Space Launch Initiative Program, where Null was a scientist in the Human Factors Divi- he was Engineering Manager and the Orbital Space Plane Team sion and Deputy Program Manager of the Space Human Factors Leader for life support and active thermal control teams. Mr. Rot- Engineering Project. Dr. Null has 22 years of experience lecturing ter has over 41 years of life support and active thermal control on Human Factors, and another 17 years of experience in Human systems experience during the Apollo, Shuttle, and Orbital Space Factors applied to NASA programs. Plane Programs. Dr. David M. Schuster Joseph W. Pellicciotti NASA Technical Fellow NASA Technical Fellow Dr. David M. Schuster is the NASA Technical Fel- Mr. Joseph W. Pellicciotti is the NASA Techni- low for Aerosciences and is resident at Langley cal Fellow for Mechanical Systems and is resi- Research Center (LaRC). Prior to joining the dent at Goddard Space Flight Center (GSFC). NESC, Dr. Schuster was the Branch Head for the Mr. Pellicciotti served as the Chief Engineer for Structural and Thermal Systems Branch in the the GSFC Mechanical Systems Division before Systems Engineering Directorate. Dr. Schuster has over 30 years joining the NESC. Mr. Pellicciotti has over 20 years of combined experience in the aerospace industry with expertise in aeroelastic- private industry and NASA experience designing structure and ity and integrated aerodynamic analysis. mechanisms for commercial, military, and civil spacecraft.

66 NESC Alumni

Glenn Research 10 Center Ames Research Center Goddard Space Flight 8 14 Center NASA Headquarters 1 7 Dryden Flight Research Center Wallops Flight MarshallMarshall Space Space Facility Langley Research Flight CenterFlight Center Center Jet Propulsion Laboratory 13 2 6 9

Kennedy Space Center 11 12 4 5 15 16 Johnson Space Stennis Space 17 18 Center Center

1 7 15 Frank H. Bauer Dr. Richard J. Gilbrech Michael W. Kehoe John P. McManamen NESC Discipline Expert for Guidance NESC Deputy Director (2003–05) Left NESC Chief Engineer at Dryden Flight NASA Technical Fellow for Mechani- Navigation and Control (2003–04) Cur- the NESC to become the LaRC Deputy Research Center (DFRC) (2003–05) Left cal Systems (2003–07) Currently the rently serving as the Exploration Sys- Center Director, in 2006 was named as the NESC to become the DFRC Liaison Chief Engineer, Shuttle Program Office tems Mission Directorate Chief Engi- the Stennis Space Center Director, and in the Crew Exploration Vehicle Flight at JSC neer at NASA HQ is currently the Associate Administrator Test Office at JSC and has since retired 16 for the Exploration Systems Mission Brian K. Muirhead J. Larry Crawford Directorate Robert A. Kichak NESC Chief Engineer at NASA’s Jet NESC Deputy Director for Safety (2003– NESC Discipline Expert for Power and Propulsion Laboratory (JPL) (2005–07) 8 04) Left NESC to become Director of Michael Hagopian Avionics (2003–07) Retired Currently the Program Systems En- Safety and Mission Assurance at the NESC Chief Engineer at Goddard gineer in the Constellation Program’s Dr. Dean A. Kontinos 10 Kennedy Space Center (KSC) and has Space Flight Center (GSFC) (2003–07) Systems Engineering Office at JSC since retired Currently the Chief Engineer in the NESC Chief Engineer at Ames Re- Engineering Directorate at GSFC search Center (ARC) (2006–07) Left the Dr. Paul M. Munafo Steven F. Cash 2 NESC to work a detailed assignment as NESC Deputy Director (2003–04) David A. Hamilton NESC Chief Engineer at Marshall the Technical Integration Manager of Left the NESC to become the Assistant Space Flight Center (MSFC) (2005) NESC Chief Engineer at Johnson Space the Fundamental Aeronautics Program Director for Safety and Engineering at Currently the Manager, Shuttle Propul- Center (JSC) (2003–07) Retired in the Aeronautics Research Mission Marshall Space Flight Center (MSFC) sion Office at MSFC 9 Directorate at NASA HQ. Has since re- and has since retired Dr. Charles E. Harris turned to ARC in the Office of the Chief Derrick J. Cheston 3 NESC Principal Engineer (2003–06) Cur- Engineer Stan C. Newberry rently the Director, Research & Technol- Manager of NESC’s Management and NESC Chief Engineer at Glenn Re- 11 search Center (2003–07) Left the NESC ogy Directorate at LaRC Julie A. Kramer White Technical Support Office (2003–04) Left to participate in the Senior Executive NESC Discipline Expert for Mechanical NESC to become the Deputy Center Di- Dr. Steven A. Hawley Service Candidate Development Pro- Analysis (2003–06) Currently the Chief rector at Ames Research Center (ARC) NESC Chief Astronaut (2003–04) Left gram (SESCDP) Engineer, Crew Exploration Vehicle and has since left NASA to accept a the NESC to become the Director of Office at JSC position at DoD 4 Freddie Douglas, III Astromaterials Research and Explora- Steven G. Labbe 12 17 NESC Chief Engineer at Stennis Space tion Science at Johnson Space Center Dr. Shamim A. Rahman NESC Discipline Expert for Flight Sci- Center (SSC) (2007–08) Currently the (JSC) and has since retired NESC Chief Engineer at Stennis Space ences (2003–06) Currently the Chief Manager, Office of Safety and Mission Center (2005–06) Currently the Deputy Marc S. Hollander Engineer, Constellation Program Office Assurance at SSC Director of the Engineering and Test Di- Manager, Management and Technical at JSC rectorate at SSC Dr. Michael S. Freeman Support Office (2005-06) Currently As- Matthew R. Landano 13 18 NESC Chief Engineer at Ames Research sociate Director for Management, Na- Jerry L. Ross NESC Chief Engineer at NASA’s Jet Center (ARC) (2003–04), Retired tional Institutes of Health NESC Chief Astronaut (2004–06) Cur- Propulsion Laboratory (JPL) (2003–04) rently the Chief of the Vehicle Integra- T. Randy Galloway 5 George D. Hopson Returned to his assignment at JPL as tion Test Office at JSC NESC Chief Engineer at Stennis Space NASA Technical Fellow for Propulsion the Director of Office of Safety and Mis- Center (SSC) (2003–04) Currently the (2003–07), Retired sion Success John E. Tinsley Director of the Engineering and Test Di- NASA Headquarters Senior Safety and Keith L. Hudkins David S. Leckrone 14 rectorate at SSC Mission Assurance Manager for NESC NASA Headquarters Office of the Chief NESC Chief Scientist (2003–06) Cur- (2003–04) Left NESC to become the Di- Dr. Edward R. Generazio 6 Engineer Representative (2003–07), rently the Senior Project Scientist for rector of the Mission Support Division NESC Discipline Expert for Nonde- Retired the Hubble Space Telescope at GSFC at NASA Headquarters and has since structive Evaluation (2003–05) Currently left NASA to accept a position with Danny D. Johnston a Senior Research Engineer, Research Northrop Grumman NESC Chief Engineer at Marshall Space & Technology Directorate, LaRC Flight Center (MSFC) (2003–04) Left the NESC to work a detailed assignment at MSFC in the NASA Chief Engineer’s Of- fice and has since retired 67 NESC Honor Awards

2008 NESC Honor Award Recipients: From left (back row): Ralph Roe, Jr. (NESC Director/Presenter); Norman Knight, Jr. (General Dynamics); Erik Weiser (LaRC); Jon Haas (WSTF); Jerry Stuart (Northrop Grumman); Lawrence Pelham (MSFC); David Dawicke (AS&M, Inc.); David Roberts (LaRC); Walter McCabe (ATK); From left (front row): Kenny Elliott (LaRC); Kenneth Hodges (JSC); Erik Tyler (AMA); Michael Dube (GSFC); Anna Jackson (LaRC); David Shemwell (independent consultant); Darcy Miller (KSC); James Beaty (LaRC); William Sipes (independent consultant); Raymond Lanzi (WFF); George Slenski (ATK Space); Ivatury Raju (NESC); Henning Leidecker (GSFC); James Fesmire (KSC); Kenneth Cameron (NESC Chief Astronaut/Presenter); Tim Wilson (NESC Deputy Director/Presenter). Not pictured: John Graf (JSC)

NESC DIRECTOR’S AWARD NESC ENGINEERING Walter Thomas McCabe, Jr. Michael J. Dube EXCELLENCE AWARD In recognition of exceptional technical excellence in the manufacture of the In recognition of technical excellence in Raymond J. (Jim) Lanzi the support and resolution of anomalies In recognition of exceptional technical composite crew module. for NASA projects across the Agency support in the fundamental design of the David M. Shemwell including the Space Shuttle, International NESC’s Max Launch Abort System flight In recognition of outstanding technical Space Station, and multiple robotic test vehicle. leadership in the investigations into spacecraft. innovative crew seat concepts for the Orion James R. Beaty Kenny B. Elliott In recognition of exceptional technical Crew Module and alternative approaches In recognition of technical excellence in support in flight mechanics stability and to occupant impact tolerance modeling. the load redefinition and redirection of control engineering for the NESC’s Max George A. Slenski the Max Launch Abort System flight test Launch Abort System Flight Test Vehicle In recognition of exceptional technical vehicle. system concept development. expertise in the failure analysis of the STS- 115 fuel cell motor anomaly. John C. Graf David S. Dawicke In recognition of technical excellence in In recognition of exceptional technical Jerry L. Stuart the investigation of the Self Contained support in the testing of the Ares I-X Upper In recognition of exceptional technical Oxygen Generator explosion on a British Stage Simulator welds. excellence in the design and manufacture Royal Navy submarine. of the NESC composite crew module. Kenneth L. Hodges In recognition of exceptional technical Erik D. Tyler NESC LEADERSHIP AWARD excellence in the design, development, In recognition of exceptional technical Larry I. Pelham and implementation of state-of-the- excellence in the computational aero- In recognition of outstanding leadership art nondestructive techniques for the dynamics and structural analysis of Max of a diverse team of Agency and industry composite crew module project. Launch Abort System concepts enabling efficient development of the flight test experts to design and manufacture the Norman F. Knight, Jr. NESC composite crew module full and In recognition of exceptional technical vehicle. subscale hardware. excellence in the analyses contributions to the Ares I-X Upper Stage Simulator Critical Initial Flaw Size.

68 NESC Honor Awards

Awards Con’t.

NESC GROUP Human Factors Pathfinder Core Team NESC Ares I-X Upper Stage Simulator ACHIEVEMENT AWARD for Ground System Designers Critical Initial Flaw Size Analysis Team In recognition of outstanding contributions Self Contained Oxygen Generator In recognition of technical excellence in the to the engineering excellence of Failure Mechanisms Investigation Team analysis and engineering guidance for the Constellation ground systems through In recognition of outstanding efforts in design, development, and manufacturing the human factors engineering pathfinder reproducing the Self Contained Oxygen of the Ares I-X Upper Stage Simulator activity (award accepted by Darcy Miller Generator mishap, successfully identifying (award accepted by Ivatury Raju on behalf on behalf of the team). the contributing factors, and developing of the team). effective corrective actions (award accepted by Jon Haas on behalf of the Ice Mitigation Approaches for Space Pyrovalve Y-PCA (Primer Carrier As- team). Shuttle External Tank Team sembly) Assessment Team In recognition of technical excellence In recognition of outstanding contributions to develop, test, and successfully 8% Max Launch Abort System investigating the Pyrovalve Y-PCA booster demonstrate two innovative solutions that Model Team failures (award accepted by William Sipes mitigate risks posed by ice liberating from In recognition of outstanding efforts in on behalf of the team). the external tank (award accepted by Erik designing, fabricating, and testing the 8% Weiser on behalf of the team). Max Launch Abort System model (award Space Shuttle Program Engine Cut-Off accepted by David Roberts on behalf of System Investigation Team the team). Langley Research Center Mission In recognition of technical excellence in Support Team the evaluation of the operational anomalies In recognition of exceptional service, External Tank Intertank/LH2 (Liquid and reliability improvements associated dedication and a proactive approach to Hydrogen) Flange Y-joint Evaluation with the Space Shuttle Engine Cut-Off providing the mission support services Assessment Team system (award accepted by Henning which have enabled the NESC to In recognition of outstanding technical Leidecker on behalf of the team). accomplish critical mission objectives support for the External Tank Intertank/ (award accepted by Anna Jackson on Liquid Hydrogen Flange Y-joint evaluation behalf of the team). (award accepted by James Fesmire on behalf of the team).

IN MEMORIA Paul D. Guy, recipient of the 2007 NESC Engineering Excellence Award for his leadership and contributions to the independent review for the Phoenix Project, unexpectedly passed away in November 2007. Dr. Gopal M. Rao, a key contributor to NESC’s NASA Aerospace Flight Battery Program, also passed in May 2008. Both are missed and will be remembered for their significant contributions to the NESC and Goddard Space Flight Center.

69 Recent NESC Publications

Reports ET Ice Mitigation ...... TM-2008-215324 & 215325 Prebreath Protocol for Extra-Vehicular Activity Technical Consultation Report ...... TM-2008-215124 Eight-Foot High Temperature Tunnel (HTT) Oxygen Storage Pressure Vessel Inspection Requirements ...... TM-2008-215316 ISS Fiber Optics Workmanship ...... TM-2008-215525 Engine Cut-Off (ECO) Sensor Reliability Testing ...... TM-2008-215332 CMG1 Root Cause Analysis ...... TM-2008-215329 Design Development Test & Evaluation (DDT&E) Considerations for Robust and Reliable Human Rated Systems ...... TM-2008-215126 Conax Y-PCA (Primer Chamber Assembly) Booster Anomaly Investigation ...... TM-2008-215548 External Tank (ET) Foam Thermal Analysis Project ...... TM-2008-215102 Composite Crew Module Pressure Vessel ...... TM-2008-215125 Crew Launch Vehicle (CLV) Project Reaction Control System (RCS) Thrust and Propellant Weight Sizing...... TM-2008-215101 ISS S-Band Corona Discharge Anomaly ...... TM-2008-215100 ET Bipod Bolt Locking Feature Verification ...... TM-2008-215099 CEV LAS Aero Evaluation ...... TM-2008-215098 Feasibility of Conducting J-2X Engine Testing at the GRC Plum Brook Station B-2 Facility ...... TM-2008-215104 DC/DC Converter Unit Investigation ...... TM-2008-215352 & 215354 Ares I-X USS Fracture Analysis Loads Spectra Development ...... TM-2008-215335 Ares I-X USS Stress Analysis ...... TM-2008-215339 Ares I-X USS Material Testing ...... TM-2008-215338 Ares I-X Upper Stage Simulator Structural Analyses Supporting the NESC Critical Initial Flaw Size Assessment ...... TM-2008-215336 Ares I-X USS Weld Residual Stress Analysis ...... TM-2008-215339 Constellation Mass and Performance Independent Assessment ...... TM-2008-215326

Presented Papers

GN&C Engineering Best Practices for Human-Rated Spacecraft Systems ...... TM-2008-215106

The NASA Engineering & Safety Center (NESC) GN&C Technical Discipline Team (TDT): Its Purpose, Practices and Experiences ...... TM-2008-215128

Guidelines for Reliable DC/DC Converters for Space Use, J. Plante, Components for Military and Space Electronics, February 10-14, 2008, San Diego, California

Guidelines for Reliable DC/DC Converters for Space Use, J. Shue, J. Plante, MAPLD 2008, September 15–18, 2008, Annapolis, Maryland

Rescuing EDL Data , Elmain Martinez, Adrian Tinio, Mike Gangl, Robert Powers, Keith Shackelford, Alan Wood, Russel Westbrook, International Planetary Probe Workshop, Atlanta, Georgia, June 23-27, 2008

NASA Experience with Pogo in Human Spaceflight Vehicles, C. Larsen, NASA Johnson Space Center, United States, AVT-152 Symposium on Limit Cycle Oscillation and Other Amplitude-Limited Self Excited Vibrations, North Atlantic Treaty Organization

All photos used in this publication are credited to NASA except where indicated

70 71 National Aeronautics and Space Administration Langley Research Center Hampton, VA 23681 www.nasa.gov NP-2008-12-135-LaRC