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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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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Hanover, MD 21076-1320 Springfield, VA 22161-2171 

(301) 621-0390 (703) 605-6000 
NASA Engineering and Safety Center 

Consultation Position Paper

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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 
NASA Engineering and Safety Center 

Consultation Position Paper

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Signature Page 

NESC Independent Technical Assessment Team

Steven J. Gentz, NESC Lead John D. Azzolini, GSFC 

Cornelius J. (Neil) Dennehy, GSFC Rodger E. Farley, GSFC 

Brent N. Heard, LaRC Robert F. Hodson, LaRC 

Frank J. Kirchman, GSFC John E. Pandolf, LaRC 

Duane H. Pettit, LaRC Peter D. Spidaliere, JSC
NASA Engineering and Safety Center 

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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 MultiLayer 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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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. 
NASA Engineering and Safety Center 

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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

 757-864-9263 

Date Consultation Concluded: 12 August 2004

Consultation and Assessment Team 

Last 

Name First Name Center Office Number Email 

Gentz1 Steven LaRC 757-864-9263 Steven.J.Gentz@nasa.gov

Azzolini John GSFC 301-286-8480 John.D.Azzolini@nasa.gov

Dennehy Neil GSFC 301-286-5696 Cornelius.J.Dennehy@nasa.gov

Farley Rodger GSFC 301-286-2252 Rodger.E.Farley@nasa.gov

Heard Brent LaRC 757-864-5021 Brent.N.Heard@nasa.gov

Hodson Bob LaRC 757-864-2326 Robert.F.Hodson@nasa.gov 

Kirchman Frank GSFC 301-286-9292 Frank.J.Kirchman@nasa.gov

Pandolf John LaRC 757-864-9624 John.E.Pandolf@nasa.gov

Pellicciotti Joe GSFC 301-286-9292 Joseph.W.Pellicciotti@nasa.gov

Pettit Duane LaRC 757-864-5224 Duane.H.Pettit@nasa.gov

Spidaliere Pete JSC 281-483-9721 Peter.D.Spidaliere@nasa.gov

McAlhaney Lisa LaRC 757-864-2139 Lisa.A.Mcalhaney@nasa.gov

Herman Natasha LaRC 757-864-3811 N.M.Herman@larc.nasa.gov

Kalinowski2 Keith GSFC 301-286-3369 J.Keith.Kalinowski@nasa.gov

Schaffer3 Matt HQ - Code T 202-358-4240 Matthew.Schaffer-1@nasa.gov 

Duh4 Jen Chow (JC) HQ - Code D 202-358-2225 JCDuh@nasa.gov 

Sarsfield4 Liam HQ - Code D 202-358-1870 Liam.P.Sarsfield@nasa.gov 

Hwa5 Vicky HQ - Code B 202-358-4336 Vicky.Hwa@nasa.gov 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 
NASA Engineering and Safety Center 

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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
NASA Engineering and Safety Center 

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Milestone Date

Kickoff Teleconference 20 July 2004 

Status Teleconference with Stakeholders 23 July 2004 

GSFC TIM 28 - 29 July 2004 

Interim Status Briefing to Stakeholders 3 August 2004

Final Report Submission 24 August 2004 

Data Reviewed

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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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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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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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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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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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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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-HDBK217 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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• 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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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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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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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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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 

(EST) 

Topic/Activity Presenter/Participants

8:30 Welcome, Safety/Emergency Procedures, 

Logistics, and Facility Information 

Gentz 

8:45 Assessment/Meeting Objective Gentz

9:15 Initial Comments 

- Reliability 

- Mechanical Systems 

- Guidance, Navigation and Control 

- Power & Avionics 

- Scientific Payloads 

- Systems Engineering 

Team

11:30 Lunch

12:30 Travel to Lockheed Martin Corporation 

Facility 

7474 Greenway Center Drive 

Building 229, Suite 200 

301-901-6174 

Team

13:00 Mission Operations, Systems Engineering, 

and Software (MOSES) Program Review 

- NESC Purpose and Introduction 

- CHAMP/MOSES HST Role 

- Data Management 

- Electrical Power 

- Mechanisms

- Instrumentation & Communication 

Gentz 

Cruz 

Regalado 

Krol 

Mathews 
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- Optical Telescope Assembly 

- Science Instruments 

- Pointing Control/Sensor Calibration 

- Thermal 

- Safing 

- Operations (FOT, HSTARs, 

Briefings, etc.) 

- Systems Management 

Wynn 

Wenz 

Bassford/Heeler 

Smith 

Cottingham

Myslinski 

Goulet 

Haskins 

15:30 Travel to GSFC, Building 33 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 

(EST) 

Topic/Activity Presenter/Participants

8:30 Prior Days Review and Current Day Plan Gentz 

9:00 Carryover Topics from Wednesday 

Document Review and Open Discussion 

Team

11:15 HST Program Office Discussion 

12:00 Lunch

13:00 Code T Status Outline Team

15:00 Open Discussion Team

16:30 TIM Summary/Action Items Gentz 

17:30 Adjourn
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APPENDIX E

Interim Status Briefing to Admiral C. Steidle (August 3, 2004) 
NASA Engineering and Safety Center 

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NASA Engineering and Safety Center 

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NASA Engineering and Safety Center 

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NASA Engineering and Safety Center 

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NASA Engineering and Safety Center 

Consultation Position Paper

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NASA Engineering and Safety Center 

Consultation Position Paper

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System Health Assessment – Analysis of HST Health 

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NASA Engineering and Safety Center 

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NASA Engineering and Safety Center 

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NASA Engineering and Safety Center 

Consultation Position Paper

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System Health Assessment – Analysis of HST Health 

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NASA Engineering and Safety Center 

Consultation Position Paper

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NASA Engineering and Safety Center 

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APPENDIX F

HST Illustrations 

High gain antenna

Aperture door

Secondary mirror

Primary

mirror

Equipment 

Section

Fine Guidance 

Sensor (3)

Aft Shroud

Axial Scientific

Instruments

Rate Sensor Units

Solar Arrays

Forward Shell

and Light Shield

Design Features of Support Systems Module 
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HST - Expanded View
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OTA ELECTRONIC BOXES

SUPPORT SYSTEMS MODULE

Optical Telescope Assembly Components 
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Approval and Document Revision History 

Approved: Original signed on file 9/16/04 

NESC Director Date 

Version Description of Revision Office of Primary Responsibility Effective 

Date 

1.0 Initial Release Principal Engineers Office 08/24/04 
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

2. REPORT TYPE 

Technical Memorandum

 4. TITLE AND SUBTITLE

Technical Consultation of the Hubble Space Telescope (HST) System 

Health Assessment – Analysis of HST Health

5a. CONTRACT NUMBER

 6. AUTHOR(S)

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

 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, DC 20546-0001

 8. PERFORMING ORGANIZATION

 REPORT NUMBER

L-19173

10. SPONSOR/MONITOR'S ACRONYM(S)

NASA

13. SUPPLEMENTARY NOTES

An electronic version can be found at http://ntrs.nasa.gov

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Category 16

Availability: NASA CASI (301) 621-0390

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email: help@sti.nasa.gov)

14. ABSTRACT

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 

18. NUMBER

 OF 

 PAGES

39

19b. TELEPHONE NUMBER (Include area code)

(301) 621-0390

a. REPORT

U

c. THIS PAGE

U

b. ABSTRACT

U

17. LIMITATION OF 

 ABSTRACT

UU

Prescribed by ANSI Std. Z39.18

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3. DATES COVERED (From - To)

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

104-08-33

11. SPONSOR/MONITOR'S REPORT

 NUMBER(S)

NASA/TM-2005-213917

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PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS.

1. REPORT DATE (DD-MM-YYYY)

01- 09 - 2005