Full report

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NASA/TM-2005-213917/Version 1.0 NESC-RP-04-12/04-060-E Technical Consultation of the Hubble Space Telescope (HST) System Health Assessment - Analysis of HST Health Steven J. Gentz, Brent N. Heard, Robert F. Hodson, Duane H. Pettit, and John E. Pandolf NASA Langley Research Center, Hampton, Virginia John D. Azzolini, Cornelius J. Dennehy, Rodger E. Farley, and Frank J. Kirchman NASA Goddard Space Flight Center, Greenbelt, Maryland Peter D. Spidaliere NASA Johnson Space Center, Houston, Texas September 2005

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The NASA STI Program Office . . . in Profile Since its founding, NASA has been dedicated to the advancement of aeronautics and space science. The NASA Scientific and Technical Information (STI) Program Office plays a key part in helping NASA maintain this important role. The NASA STI Program Office is operated by Langley Research Center, the lead center for NASA’s scientific and technical information. The NASA STI Program Office provides access to the NASA STI Database, the largest collection of aeronautical and space science STI in the world. The Program Office is also NASA’s institutional mechanism for disseminating the results of its research and development activities. These results are published by NASA in the NASA STI Report Series, which includes the following report types: • TECHNICAL PUBLICATION. Reports of completed research or a major significant phase of research that present the results of NASA programs and include extensive data or theoretical analysis. Includes compilations of significant scientific and technical data and information deemed to be of continuing reference value. NASA counterpart of peerreviewed formal professional papers, but having less stringent limitations on manuscript length and extent of graphic presentations. • TECHNICAL MEMORANDUM. Scientific and technical findings that are preliminary or of specialized interest, e.g., quick release reports, working papers, and bibliographies that contain minimal annotation. Does not contain extensive analysis. • CONTRACTOR REPORT. Scientific and technical findings by NASA-sponsored contractors and grantees. • CONFERENCE PUBLICATION. Collected papers from scientific and technical conferences, symposia, seminars, or other meetings sponsored or co-sponsored by NASA. • SPECIAL PUBLICATION. Scientific, technical, or historical information from NASA programs, projects, and missions, often concerned with subjects having substantial public interest. • TECHNICAL TRANSLATION. Englishlanguage translations of foreign scientific and technical material pertinent to NASA’s mission. Specialized services that complement the STI Program Office’s diverse offerings include creating custom thesauri, building customized databases, organizing and publishing research results ... even providing videos. For more information about the NASA STI Program Office, see the following: • Access the NASA STI Program Home Page at http://www.sti.nasa.gov • E-mail your question via the Internet to help@sti.nasa.gov • Fax your question to the NASA STI Help Desk at (301) 621-0134 • Phone the NASA STI Help Desk at (301) 621-0390 • Write to: NASA STI Help Desk NASA Center for AeroSpace Information 7121 Standard Drive Hanover, MD 21076-1320

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NASA/TM-2005-213917/Version 1.0 NESC-RP-04-12/04-060-E Technical Consultation of the Hubble Space Telescope (HST) System Health Assessment - Analysis of HST Health Steven J. Gentz, Brent N. Heard, Robert F. Hodson, Duane H. Pettit, and John E. Pandolf NASA Langley Research Center, Hampton, Virginia John D. Azzolini, Cornelius J. Dennehy, Rodger E. Farley, and Frank J. Kirchman NASA Goddard Space Flight Center, Greenbelt, Maryland Peter D. Spidaliere NASA Johnson Space Center, Houston, Texas National Aeronautics and Space Administration Langley Research Center Hampton, Virginia 23681-2199 September 2005

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The use of trademarks or names of manufacturers in the report is for accurate reporting and does not constitute an official endorsement, either expressed or implied, of such products or manufacturers by the National Aeronautics and Space Administration. Available from: NASA Center for AeroSpace Information (CASI) 7121 Standard Drive Hanover, MD 21076-1320 (301) 621-0390 National Technical Information Service (NTIS) 5285 Port Royal Road Springfield, VA 22161-2171 (703) 605-6000

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 1 of 34 System Health Assessment – Analysis of HST Health Technical Consultation of the Hubble Space Telescope (HST) System Health Assessment - Analysis of HST Health August 24, 2004 Prepared by: Steven J. Gentz NESC Principal Engineer

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Title: Page #: Technical Consultation of the Hubble Space Telescope (HST) 2 of 34 System Health Assessment – Analysis of HST Health Signature Page NESC Independent Technical Assessment Team Steven J. Gentz, NESC Lead Cornelius J. (Neil) Dennehy, GSFC Brent N. Heard, LaRC Frank J. Kirchman, GSFC Duane H. Pettit, LaRC John D. Azzolini, GSFC Rodger E. Farley, GSFC Robert F. Hodson, LaRC John E. Pandolf, LaRC Peter D. Spidaliere, JSC

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 3 of 34 System Health Assessment – Analysis of HST Health EXECUTIVE SUMMARY On July 13, 2004, the Associate Administrator for the Office of Exploration Systems, Admiral Craig E. Steidle, with concurrence from the Chief Safety & Mission Assurance Officer, Bryan D. O’Connor, and NASA’s Chief Engineer, Theron M. Bradley, solicited support from Ralph R. Roe, NESC Director, in the evaluation of the Hubble Space Telescope’s (HST) long-term health prospects. The NESC consultation was one component of an Agency decision on the viability of extending the life of the HST through a robotic service mission (SM). To address the request within the specified parameters, a multi-Center review team of knowledgeable technical specialists was convened to analyze the current and anticipated state of spacecraft subsystems and the parameters that describe the HST health to determine the timeliness of a robotic SM and whether this type of mission is likely to provide the capability to extend the useful scientific life of the HST by 5 years. The NESC team examined numerous HST Program reports and briefings, and the findings from the Independent Program Assessment Office (IPAO) and the Aerospace Corporation Analysis of Alternatives (AOA) as they related to the degradation of the HST’s health. The NESC team also examined the state of HST subsystems that will not be serviced under the Goddard Space Flight Center (GSFC) baseline concept (Appendix A) including, but not limited to, the Fine Guidance Sensor (FGS) system, the Data Management Unit, the Multi- Layer Insulation (MLI) blankets, and the main science instrument systems. Appendix F provides HST illustrations. The technical disciplines used for this assessment were selected based on the consideration of the HST subsystems and included: Guidance Navigation and Control (GN&C), Mechanical Systems, Power and Avionics, Safety and Mission Assurance (S&MA), Scientific Payloads, and Systems Engineering. The review of the IPAO and AOA documents was supplemented with a significant quantity of HST-related reports, presentations, and other applicable references. A partial listing of these documents is located in Appendix C. In addition, extensive technical discussions were held with the HST Program liaison, numerous HST Operations, Flight Systems Engineering, Systems Management personnel and team technical peers. By design and circumstances of limited time, the approach was concurrent discipline-based with selective subsystem penetration (audit structure). This assessment method enabled rapid review of the diverse and formidable quantity of HST Program information, while allowing the identification of systemic as well as isolated system characteristics. No specific attempt was made at independent verification of trending information, mathematical models, or performance parameters. Aspects of information transfer from daily operations through HST Program review were included with the data review. This allowed an examination of information flow to ensure

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 4 of 34 System Health Assessment – Analysis of HST Health critical performance and health trends were identified and communicated through the decision chain. In summary, the NESC review team has assessed the HST Program to be: - organizationally structured to recognize performance deterioration and communicate these system changes through all levels of the Mission Operations, Systems Engineering, and Software (MOSES) team and HST Program Office; - a highly skilled personnel base to support both operations and sustaining engineering associated with a SM; - experienced in effective development and implementation of operational workarounds to provide the greatest likelihood of continued science until a SM can be effected (baring a rapid degradation in battery capacity); and - prepared with contingency plans to perform a power management protocol to maximize HST attitude control until a SM can be effected. After a thorough review of the information examined and the technical discussions held, it appears there is a high likelihood of having a viable vehicle available for a robotic SM. In addition, following successful equipment and instrument replacement during an optimized SM, the potential for at least five additional years of science discovery is very good. Recommendations are provided to aid in the decisions that will lead to an optimum SM manifest and to extend the science service life its greatest extent.

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Title: Page #: Technical Consultation of the Hubble Space Telescope (HST) 5 of 34 System Health Assessment – Analysis of HST Health NESC Position Paper Request Number #: 04-060-E Requestor Name: Craig E. Steidle Requestor Contact Info: Craig.E.Steidle@nasa.gov 202-358-1523 Short Title: Hubble Space Telescope (HST) System Health Assessment – Analysis of HST Health Degradation Description: To evaluate the long-term health of the HST through Year 2013 following a successful robotic servicing mission. Specifically, to provide input on the predicted reliability/expected availability of the major subsystems and instruments. Especially those subsystems and instruments not scheduled for servicing in the baseline concept. Date Received: 13 July 2004 Date Consultation Initiated: 13 July 2004 Lead Assigned: Steven J. Gentz Lead Contact Info: Steven.J.Gentz@nasa.gov Date Consultation Concluded: 12 August 2004 Consultation and Assessment Team Last Name First Name Center 1 Gentz Steven LaRC Azzolini John GSFC Dennehy Neil GSFC Farley Rodger GSFC Heard Brent LaRC Hodson Bob LaRC Kirchman Frank GSFC Pandolf John LaRC Pellicciotti Joe GSFC Pettit Duane LaRC Spidaliere Pete JSC McAlhaney Lisa LaRC Herman Natasha LaRC 2 Kalinowski Keith GSFC 3 Schaffer Matt HQ - Code T 4 Duh Jen Chow (JC) HQ - Code D 4 Sarsfield Liam HQ - Code D 5 Hwa Vicky HQ - Code B 1 Team Lead - NESC Principal Engineer’s Office 2 HST Liaison 3 Office of Exploration Liaison 4 Office of Chief Engineer Liaison 5 Aerospace Corporation AOA Monitor 757-864-9263 Office Number Email 757-864-9263 Steven.J.Gentz@nasa.gov 301-286-8480 John.D.Azzolini@nasa.gov 301-286-5696 Cornelius.J.Dennehy@nasa.gov 301-286-2252 Rodger.E.Farley@nasa.gov 757-864-5021 Brent.N.Heard@nasa.gov 757-864-2326 Robert.F.Hodson@nasa.gov 301-286-9292 Frank.J.Kirchman@nasa.gov 757-864-9624 John.E.Pandolf@nasa.gov 301-286-9292 Joseph.W.Pellicciotti@nasa.gov 757-864-5224 Duane.H.Pettit@nasa.gov 281-483-9721 Peter.D.Spidaliere@nasa.gov 757-864-2139 Lisa.A.Mcalhaney@nasa.gov 757-864-3811 N.M.Herman@larc.nasa.gov 301-286-3369 J.Keith.Kalinowski@nasa.gov 202-358-4240 Matthew.Schaffer-1@nasa.gov 202-358-2225 JCDuh@nasa.gov 202-358-1870 Liam.P.Sarsfield@nasa.gov 202-358-4336 Vicky.Hwa@nasa.gov

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 6 of 34 System Health Assessment – Analysis of HST Health In addition to outstanding support provided by the assessment team, the rapid response to this request could not have been accomplished without the exemplary support from the HST Program Office (Dr. Keith Kalinowski), the Lockheed Martin Corporation MOSES team (specifically, Tony Cruz, Mike Wenz, Stan Krol, Dave Haskins, Dan Smith, Mike Myslinski, Christine Cottingham, Greg Goulet, Jessica Regalado, Harry Wynn, Kevin Matthews, and Mike Prior), and the Space Telescope Science Institute representative (Manfred Miebach). Added appreciation is extended to the NESC Management and Technical Support Office (specifically Lisa McAlhaney, Natasha Herman, and Erin Moran). Consultation Approach The NESC conducted an abridged independent examination of available information and personnel interviews to evaluate the current and anticipated state of the spacecraft subsystems and the parameters that describe the HST’s health. These examinations included the projected timeliness of a robotic SM and whether the GSFC baseline concept is likely to provide the capability to extend the useful scientific life of the HST by an additional 5 years. The NESC team collected a broad spectrum of pertinent HST Program analyses, reports, briefings, and the results of the IPAO and the Aerospace Corporation AOA assessments as they relate to the degradation of the HST’s health. This review included the state of the HST subsystems having the potential to impact the viability of the HST, but will not be serviced under the baseline robotic SM. The identified documents were distributed to the NESC team for initial independent review and during a Technical Interchange Meeting (TIM) at GSFC (refer to Appendix D for the TIM agenda). Concurrent with these reviews were periodic discussions with the HST Program Liaison for clarifications to information provided and requests for further reference material. The TIM enabled in-depth exchange of information internally to the review team and externally with the HST Program personnel. In the course of these discussions and technical interchanges, additional reports and information were requested for review and evaluation. Finally, the TIM allowed for the consolidation of the various technical discipline observations into a combined package for a stakeholder interim status review (refer to Appendix E). The following are the major milestones of the NESC assessment: Milestone Date Initial Stakeholder Meeting 13 July 2004 Review Team Formulation 14 - 20 July 2004 Review HST Operations and Performance Data Packages 14 - 26 July 2004 Consultation Scope Definition 19 July 2004

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Title: Page #: Technical Consultation of the Hubble Space Telescope (HST) 7 of 34 System Health Assessment – Analysis of HST Health Milestone Kickoff Teleconference Status Teleconference with Stakeholders GSFC TIM Interim Status Briefing to Stakeholders Final Report Submission Data Reviewed Date 20 July 2004 23 July 2004 28 - 29 July 2004 3 August 2004 24 August 2004 The technical disciplines of GN&C, Mechanical Systems, Power and Avionics, S&MA, Scientific Payloads, and Systems Engineering were assigned review of their respective areas of expertise based on the following HST subsystem divisions: • Data Management • Electrical Power • Mechanisms* • Instrumentation and Communication • Optical Telescope Assembly • Science Instruments • Pointing Control • Thermal Control • Safing * Mechanisms is not typically listed as a separate subsystem for HST reporting In addition to the copious volume of information available, the method of information transfer was examined to determine if crucial information on the HST’s system health was adequately being disseminated from the MOSES team to the HST Program for review and disposition. This included the procedures used in performance and anomaly identification, reporting, and tracking. OBSERVATIONS/RECOMMENDATIONS Following are three main areas pertaining to Hardware, Operating Culture, and Reliability Analysis. The recommendations are sequentially numbered to aid discussion. HARDWARE Observations • A number of components have longevity exceeding specification life. This appears to be a combination of conservative reliability analysis assuming highly

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 8 of 34 System Health Assessment – Analysis of HST Health stressed components; quality parts screening (Grade B/NASA PPL-21 Grade 2), fabrication, and test; infant mortality culling; and refined HST operations to minimize degradation (especially to components with known performance concerns). • The HST architecture appears robust with considerable redundancy and has proven to be adaptable to unforeseen configurations. • The following components have been identified as having performance issues or require additional emphasis by the HST Program Office: - Nickel Hydrogen Batteries The HST batteries continue to have decreased capacity at a calculated total system rate of -34.2 AmpHour per year (-5.7 Ahr per battery per year). At this projected rate, the system capacity is predicted to fall below the lowest Safemode trigger of 110 Ahr at the end of 2009. Unless changes in the recharging and reconditioning procedures are validated to impede this trend, battery capacity will remain one of the two most likely system limiters for the HST. It is the principal factor in the overall observatory life projections prior to a SM. - Rate Sensor Unit (RSU) Gyroscopes Currently, RSU gyroscopes 3 and 5 have failed with gyroscope 6 held in reserve with known bias instability performance issues. To support nominal pointing control to the desired accuracy requires at least three functional gyroscopes. Reliability estimates are for a greater than 50% probability of having three gyroscopes until the beginning of 2006. The HST Program is developing a twogyroscope pointing and science scheduling capability in advance of the anticipated loss of three functional gyroscopes. Continued science observations are projected for an additional 12 to 18 months beyond the loss of a threegyroscope capability using software corrections for the known performance issues of gyroscope 6, and the implementation of a two-gyroscope operational mode. Gyroscope life is the principal factor for observatory useful science life projections and the other most likely system limiter for the HST prior to a SM. - Fine Guidance Sensors (FGSs) Three FGSs provide precise fine-pointing adjustments to tracking guide stars at sub-arcsecond levels with only two functioning FGSs required for nominal science operations. There is concern with the performance of FGS 2R and FGS 3. The effectiveness of FGS 2R is decreasing as a result of a servo-loop gain issue that is most probably due to anomalous Light Emitting Diode (LED).

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 9 of 34 System Health Assessment – Analysis of HST Health FGS 3 has significant bearing performance issues that require higher motor torques to overcome, and is being used sparingly to preserve remaining life. Life predictions for adequate FGS control vary, but appear to provide sufficient margin to the projected SM in 2008, but not to the planned end-of-life in 2013. Replacement of the FGSs was in the Orbiter SM, but is not in the baseline GSFC robotic SM. - Pointing/Safemode Electronics Assembly (PSEA) Safing Computer Daily temperature monitoring and long-term trending show the PSEA safing computer operating at the yellow high limit (49°C). The mean and maximum temperatures for the first quarter of calendar year 2004 were 40.35 and 48.29°C, respectively. The red high limit for this system is 54.5°C. The HST Program expects to initiate ground testing of a PSEA engineering unit to validate the current yellow and red high limits. The results of this testing may lead to an increase in the warning limits or may require operational controls to preclude limit violations. - Space Telescope Imaging Spectrograph (STIS) The STIS was installed on 14 February 1997 during SM 2. In the course of this assessment (3 August 2004), the STIS transitioned into a suspend mode. Preliminary findings by the Failure Review Board indicate a problem with the Side 2 +5 volt Interpoint power converter in the Mechanism Power Supply. This suspected fault is similar to an electrical malfunction that occurred in May 2001 that rendered the Side 1 electronics inoperable. • The following cross-cutting system aspects have potential concerns: - Total Ionizing Dose (TID) exposure of component electronics. The HST Program provided a technical memorandum on the “Radiation Reliability Assessment of the Hubble Space Telescope Electronics”, dated 28 February 1998. This study identified potential TID concerns through 2010. However, this study reveals that only a portion (approximately 64%) of the integrated circuits (ICs) were reviewed from the total of 1120 semiconductor devices contained in the parts list. The study does cite a number of ICs with probable degradation and potential TID issues in a number of electronic devices if not shielded in low dose areas of the vehicle. In general, the report indicates that most devices fabricated during the HST development period are relatively immune to TID effects, but later electronic upgrades may be more susceptible.

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 10 of 34 System Health Assessment – Analysis of HST Health Overall, this report provides incomplete evidence to support that the electronics are operating within TID specifications to the intended operational period of 2008 or the end-of-life date of 2013. The HST Parts Control Plan specifies a minimum TID of 15 KRads for generic parts and 5 KRads if generic data is unavailable. Surface dose can exceed a MRad/year, but diminishes rapidly with shielding. As electronics devices accumulate total dose, device power increases due to transistor parameter shifts and eventually the devices will degrade beyond operational ranges. To date, there are no known HST electronics failures due to this mechanism, but the likelihood increases with TID accumulation. – Increasing thermal environment in the HST aft shroud due to higher power consuming equipment and increased instrument utilization. This condition appears to be a result of the installation and operation of more capable science instruments that consume more power, and not a result of MLI degradation. The HST Program is performing ongoing analyses and expects to institute operational limitations to manage the thermal load. The proposed replacement of the Corrective Optics Space Telescope Axial Replacement (COSTAR) with the Cosmic Origins Spectrograph (COS) in the baseline robotic SM will increase thermal loading, as the COS is estimated to generate approximately 200 Watts versus the reported 45 Watts from COSTAR. – Review of Failure Modes and Effects Analysis (FMEA) and hazard analyses for identification of single point failures. The HST Program reported that in preparation for the Power Control Unit (PCU) replacement during SM 3B, a review of the 1987 FMEA and hazard analyses was completed at the component and system levels. This information was relayed late in the assessment period and represents a considerable quantity of additional reports only available though an internal GSFC document control system. No comprehensive review was performed by the NESC team and will be forwarded as a recommendation to the HST Program for completion prior to a robotics SM Critical Design Review (CDR). – B-side electronics has not been exercised since prior to launch and has an assumed reliability of 1 and a failure rate equal to 10% of the operating value. The architectural design of the HST does not allow periodic verification of the redundant electronics circuitry without considerable disruption to science

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 11 of 34 System Health Assessment – Analysis of HST Health operations and the potential risk to recovery of A-side operations. Ground testing is assumed to have ensured the absence of latent defects in the electrical components and manufacturing. However, the STIS has been the only system that required the use of the redundant electronics. This assumed reliability represents the HST Program’s recognized systemic risk. September 2002 is the most recent HST Program assessment of the effort involved to prepare, verify, and implement on-orbit testing of the HST’s redundant components. It concluded verification of the B-side electronics was not recommended due to a number of factors that included a small, but non-zero, risk that one of the power-cycled modules would not restart. – Continued degradation of the MLI outer ply due to environmental exposure. Prior SMs observed a greater degradation than expected and implemented rudimentary fixes including application of New Outer Blanket Layer (NOBL) material to minimize material and thermal performance loss. Increased damage is predicted during the next several years of solar minimum. The potential for dislodged MLI becoming a contamination concern during future servicing requires assessment and mitigation. – A number of components have service exposure greater than design life. The contributing factors that have resulted in the exemplary success of a majority of components are understood from at least a qualitative standpoint. However, electrical and mechanical components cannot be expected to survive indefinitely. Recognition of performance issues will continue to rely on telemetry for long-term health assessment. Graceful failure modes with gradual precursor performance indicators cannot always be expected. A structured Life Extension Initiative defined by the HST Program is a mechanism to explore anomaly detection, fault progression, and failure modes. Recommendations 1.1 Continue the evaluation of recommendations on life prediction and battery capacity protocol identified in NESC Report, “Technical Consultation of the Hubble Space Telescope (HST) Nickel Hydrogen (NiH2) Battery Charge Capacity Prediction”, NESC 04-050-E, dated 17 June 2004. 1.2 Assess the augmentation of GSFC baseline robotic SM to include replacement of at least one FGS. 1.3 Complete planned ground testing to determine thermal margin limits of PSEA Safing computer prior to robotic SM CDR. Update thermal warning high limits

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 12 of 34 System Health Assessment – Analysis of HST Health or institute operational controls to limit temperature exposure to within allowable operational ranges. If thermal limits can not be successfully raised, then assess potential for augmentation of GSFC baseline robotic SM to include replacement or redundant Safing computer. 1.4 Locate and update, or generate, a comprehensive TID exposure analysis of HST components to identify any elements at risk to performance degradation for the intended operational period of 2008 and to the end-of-life date of 2013. This analysis should be completed or updated prior to the robotic SM CDR. 1.5 Release an operational plan to address aft shroud thermal environment conditions prior to the robotic SM CDR. Update this plan to consider impact of de-orbit module attachment and the replacement instruments and components as part of any SM concept. 1.6 Complete an updated review of the FMEA and hazard analyses for the identification of single point failures prior to the robotic SM CDR. Assess the potential for augmentation of GSFC baseline robotic SM based on this review. 1.7 Confirm thermal margins with respect to expected increased degradation of MLI outer ply prior to the robotic SM CDR. 1.8 Identify contamination control protocol to mitigate risk of degraded MLI migration into internal structure of the HST during a SM. 1.9 Pursue a structured Life Extension Initiative prioritized on component criticality. OPERATING CULTURE Observations • The HST Program appears to be a highly motivated and resourceful team with extensive corporate knowledge that has repeatedly demonstrated the ability to react to and plan for adverse conditions. A number of innovation applications of HST systems to non-traditional roles are considered in fault planning. This team has operations rooted in established procedures and a layered approach to anomaly recognition and disposition. • The HST Program team appears to practice an iterative SM versus End-of-Life paradigm. This manifests as data trending of performance parameters directed towards near-term problem recognition and characterization. The HST team has the prerequisite skills and data available to make these predictions and this observation may be one of nomenclature. However, clarification should be provided to the MOSES team on the

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 13 of 34 System Health Assessment – Analysis of HST Health scope of their overall long-term telemetry/performance trending efforts. Recommendation 2.1 Provide specific direction to HST Systems Engineers to complete end-of-life predictions for major components and subsystems with continuous updates from telemetry data and ground-based Life Extension Initiative results prior to the robotic SM CDR. RELIABILITY ANALYSIS Observations • The reliability analysis updated by the Aerospace Corporation uses typical assumptions, failure rate updating, and modeling consistent with MIL-HDBK- 217 methodology. – Two methods were used to update the 1992 failure rate predictions. First, the methodology (RADC-TR-85-229) developed by the Reliability Analysis Center is used to reduce the failure rate to 60% of the original MIL-HDBK-217 failure rates. This methodology is typically used by current satellite manufacturers. The second update uses operational experience to adjust the HST subsystem failure rates. By using a Bayesian methodology, the “a priori,” or original estimate, can be updated. This methodology is also common in reliability engineering and Probabilistic Risk Assessments (PRAs). • The current reliability analysis models only electronic failure rates with the exception of the RSU gyroscopes, where a mechanical wear out rate is applied. – The HST has many mechanical systems that should be modeled in the reliability analysis. To perform a Bayesian update to include both HST electrical and mechanical components, shape and scale parameters and gamma distributions are required. These values can be based on hardware experience and engineering estimations. These refined parameters would then be used to adjust component failure rates. Since there are many different types of subsystems in HST, the observed data accumulated over its life may be used to develop different shape parameters for each subsystem and then adjust each failure rate accordingly. Following these failure rate adjustments, the models developed in the original HST Reliability Assessment could be used to more accurately represent the current and expected reliability of the HST.

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 14 of 34 System Health Assessment – Analysis of HST Health • MIL-HDBK-217 unique analyses are intended to be a design trade tool and not an absolute estimate of component field (in-service) failures. Recommendations 3.1 Update the reliability model from the August 2003 release to account for HST performance experience to date. 3.2 Perform sensitivity studies on shape and scale parameters of current reliability analysis to determine if there is a change to the HST reliability drivers. 3.3 Update the reliability analysis to incorporate shape and scale parameters and gamma distributions for the electrical and mechanical components using accumulated time and failures experienced during on-orbit operations.

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Title: Page #: Technical Consultation of the Hubble Space Telescope (HST) 15 of 34 System Health Assessment – Analysis of HST Health APPENDIX A Orbiter SM4 Planned Manifest Cosmic Origins Spectrograph (COS) Wide Field Camera 3 (WFC 3) Fine Guidance Sensor (FGS) Aft Shroud Cooling System Batteries Gyroscopes New Outer Blanket Layer (NOBL) Data Handling Cross Strap Unit (DSC) GSFC Baseline Robotic SM4 Proposed Manifest Cosmic Origins Spectrograph (COS) Wide Field Camera 3 (WFC 3) Batteries Gyroscopes

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 16 of 34 System Health Assessment – Analysis of HST Health APPENDIX B List of Acronyms Ahr AmpHour AOA Analysis of Alternatives CDR Critical Design Review COS Cosmic Origins Spectrograph COSTAR Corrective Optics Space Telescope Axial Replacement DC Direct Current DSC Data Handling Cross Strap Unit FGS Fine Guidance Sensor FMEA Failure Modes and Effects Analysis GN&C Guidance Navigation and Control GSFC Goddard Space Flight Center HQ Headquarters HST Hubble Space Telescope IC Integrated Circuit IPAO Independent Program Assessment Office LaRC Langley Research Center LED Light Emitting Diode JSC Johnson Space Center KDDL Known Data Discrepancy List MLI Multi-Layer Insulation MOSES Mission Operations, Systems Engineering, and Software NOBL New Outer Blanket Layer NRB NESC Review Board PCU Power Control Unit PRA Probabilistic Risk Assessment PSEA Pointing/Safemode Electronics Assembly RSU Rate Sensor Unit S&MA Safety and Mission Assurance SM Service Mission STIS Space Telescope Imaging Spectrograph TID Total Ionizing Dose TIM Technical Interchange Meeting WFC Wide Field Camera

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 17 of 34 System Health Assessment – Analysis of HST Health APPENDIX C HST Program Reports and Briefings HST Program Reports and Briefings – Mission Operations, Systems Engineering, and Software Program Observatory Performance Assessment Quarterly Reports (June 2004, 2003, and 2001) – 26 July 2004, Mission Operations Snapshot – 15 July 2004, Mission Operations, Systems Engineering, and Software Program Quarterly Briefing – 22 June 2004, HST Survivability; Comparison of Servicing Tasks – 17 June 2004, Technical Consultation of the Hubble Space Telescope (HST) Nickel Hydrogen (NiH2) Battery Charge Capacity Prediction, NESC 04-050-E – 10 June 2004, Known Data Discrepancy List (KDDL) – 9 June 2004, Comments on RSU being located on the De-orbit Module, EM HST-04-004A – 2 & 3 June 2004, Status of Hubble Spacecraft – 2 June 2004, Hubble Science Operations – 28 April 2004, Effect of WFPC3 Mechanism Disturbances on RGA and PCS, EM HST-04- 001A – 18 December 2003, Limited Life Items and Risk Mitigation List (SM-4) – 15 July 2003, Anomaly Reporting for HST Operations and Test – 9 September 2002, Impacts and Risks of On-Orbit Testing of HST’s Redundant Modules – 13 February 2002, HST Cargo Systems Manual – 2 August 2001, STIS Failure Review Board Final Report – 13 & 14 May 2004, HST Robotic Servicing Concept Review – 1 April 1997, HST Parts and Control Plan – 1991, The Flight Hardware and Ground System for HST Astrometry Aerospace Corporation Reliability Model – July 2002, HST Reliability Assessment, Report No. TOR-2003(2154)-2352 – August 2003, Adjusted Reliability Model for Science Operations Independent Program Assessment Office (IPAO) Briefings – 21 through 24 June 2004, Briefings – 20 July 2004, Final Review Briefing Aerospace Corporation Analysis of Alternatives (AOA) Briefing – 9 July 2004, Mid Term Briefing – 3 August 2004, Final Review Briefing Lockheed Martin Technical Memorandum TM12-97 – 28 February 1998, Radiation Reliability Assessment of the Hubble Space Telescope Electronics

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 18 of 34 System Health Assessment – Analysis of HST Health APPENDIX D Hubble Space Telescope (HST) System Health Independent Technical Consultation Technical Interchange Meeting July 28-29, 2004 Proposed Agenda Wednesday, July 28, 2004 GSFC East, Building 33, Conference Room H118 Time Topic/Activity Presenter/Participants (EST) Welcome, Safety/Emergency Procedures, Gentz 8:30 Logistics, and Facility Information 8:45 Assessment/Meeting Objective Gentz Team 9:15 Initial Comments - Reliability - Mechanical Systems - Guidance, Navigation and Control - Power & Avionics - Scientific Payloads - Systems Engineering 11:30 Lunch Travel to Lockheed Martin Corporation Team 12:30 Facility 7474 Greenway Center Drive Building 229, Suite 200 301-901-6174 13:00 Mission Operations, Systems Engineering, and Software (MOSES) Program Review - NESC Purpose and Introduction CHAMP/MOSES HST Role Gentz - Cruz - Data Management Regalado - Electrical Power Krol - Mechanisms Instrumentation & Communication Mathews -

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Title: Page #: Technical Consultation of the Hubble Space Telescope (HST) 19 of 34 System Health Assessment – Analysis of HST Health Optical Telescope Assembly Wynn - - Science Instruments Pointing Control/Sensor Calibration Wenz - - Thermal - Safing - Operations (FOT, HSTARs, Briefings, etc.) - Systems Management 15:30 Travel to GSFC, Building 33 Bassford/Heeler Smith Cottingham Myslinski Goulet Haskins Team 16:00 Working Session and Open Discussion Team 17:00 Summary/Action Items/ Issues Gentz 17:30 Adjourn Thursday, July 29, 2004 GSFC East, Building 33, Conference Room H118 Time Topic/Activity Presenter/Participants (EST) 8:30 Prior Days Review and Current Day Plan Gentz Carryover Topics from Wednesday Team 9:00 Document Review and Open Discussion 11:15 HST Program Office Discussion 12:00 Lunch 13:00 Code T Status Outline 15:00 Open Discussion 16:30 TIM Summary/Action Items 17:30 Adjourn Team Team Gentz

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 20 of 34 System Health Assessment – Analysis of HST Health APPENDIX E Interim Status Briefing to Admiral C. Steidle (August 3, 2004)

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 21 of 34 System Health Assessment – Analysis of HST Health

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Title: Page #: Technical Consultation of the Hubble Space Telescope (HST) 31 of 34 System Health Assessment – Analysis of HST Health APPENDIX F HST Illustrations Equipment Section Fine Guidance Sensor (3) Aft Shroud Axial Scientific Instruments Rate Sensor Units High gain antenna Secondary mirror Primary Aperture door mirror Forward Shell and Light Shield Solar Arrays Design Features of Support Systems Module

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 32 of 34 System Health Assessment – Analysis of HST Health HST - Expanded View

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Page #: Title: Technical Consultation of the Hubble Space Telescope (HST) 33 of 34 System Health Assessment – Analysis of HST Health SUPPORT SYSTEMS MODULE OTA ELECTRONIC BOXES Optical Telescope Assembly Components

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NASA Engineering and Safety Center Document #: Version #: Consultation Position Paper RP-04-12 1.0 Title: Page #: Technical Consultation of the Hubble Space Telescope (HST) 34 of 34 System Health Assessment – Analysis of HST Health Approval and Document Revision History Approved: Original signed on file NESC Director Version Description of Revision 1.0 Initial Release 9/16/04 Date Office of Primary Responsibility Effective Date Principal Engineers Office 08/24/04

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Form Approved REPORT DOCUMENTATION PAGE OMB No. 0704-0188 The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE (DD-MM-YYYY) 2. REPORT TYPE 01- 09 - 2005 Technical Memorandum 4. TITLE AND SUBTITLE Technical Consultation of the Hubble Space Telescope (HST) System Health Assessment – Analysis of HST Health 6. AUTHOR(S) 3. DATES COVERED (From - To) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER Gentz, Steven J.; Heard, Brent N.; Hodson, Robert F.; Pettit, Duane H.; Pandolf, John E.; Azzolini, John D.; Dennehy, Cornelius J.; Farley, Rodger E.; Kirchman, Frank J.; and Spidaliere, Peter D. 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) NASA Langley Research Center Hampton, VA 23681-2199 5e. TASK NUMBER 5f. WORK UNIT NUMBER 104-08-33 8. PERFORMING ORGANIZATION REPORT NUMBER L-19173 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S) National Aeronautics and Space Administration Washington, DC 20546-0001 12. DISTRIBUTION/AVAILABILITY STATEMENT Unclassified - Unlimited Subject Category 16 Availability: NASA CASI (301) 621-0390 13. SUPPLEMENTARY NOTES An electronic version can be found at http://ntrs.nasa.gov 14. ABSTRACT NASA 11. SPONSOR/MONITOR'S REPORT NUMBER(S) NASA/TM-2005-213917 The NESC conducted an abridged independent examination of available information and personnel interviews to evaluate the current and anticipated state of the spacecraft subsystems and the parameters that describe the HST’s health. These examinations included the projected timeliness of a robotic SM and whether the GSFC baseline concept is likely to provide the capability to extend the useful scientific life of the HST by an additional 5 years. The NESC team collected a broad spectrum of pertinent HST Program analyses, reports, briefings, and the results of the IPAO and the Aerospace Corporation AOA assessments as they relate to the degradation of the HST’s health. This review included the state of the HST subsystems having the potential to impact the viability of the HST, but will not be serviced under the baseline robotic SM. 15. SUBJECT TERMS Battery capacity; GN&C; Health; HST; Life predictions; NESC; Nickel hydrogen batteries; Reliability analysis; Rate sensor unit; Servicing mission 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT a. REPORT b. ABSTRACT c. THIS PAGE U U U UU 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON OF PAGES STI Help Desk (email: help@sti.nasa.gov) 19b. TELEPHONE NUMBER (Include area code) 39 (301) 621-0390 Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18