Assessment of Options for Extending the Life of the Hubble Space Telescope Final Report (2005) / Chapter Skim
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6 Space Shuttle Servicing of Hubble
6 Space Shuttle Servicing of Hubble
Pages 74-91
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From page 74... ...
Each mission improved the observatory's capabilities and enhanced its reliability while also satisfying the overriding servicing maxim "do no harm." This chapter examines certain mission viability factors, other operational considerations, relevant prior servicing missions successes, and mission and crew safety risk considerations in servicing HST using the space shuttle during the flight operations that will follow the return to flight following the Columbia accident. REQUIREMENTS AFFECTING THE VIABILITY OF A SHUTTLE MISSION TO HST WHILE MEETING THE CAIB AND NASA RETURN-TO-FLIGHT REQUIREMENTS The committee takes as its starting point that NASA will meet the Columbia Accident Investigation Board (CAIB)
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From page 75... ...
Additional applicable NASA RTF activities that affect the viability of an HST mission follow: Space Shuttle Program Action SSP-3 -- Contingency Shuttle Crew Support [Safe Haven] :3 NASA will evaluate the feasibility of providing contingency life support on board the International Space Station (ISS)
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From page 76... ...
NASA Administrator's Considerations In the committee's discussions with the NASA administrator, it was clear that he considers that three key elements differentiate a shuttle mission to ISS from a servicing mission to Hubble; these elements determined his overarching rationale for cancellation of the shuttle HST servicing mission: 1. Crew safety -- Additional crew risk incurred on an HST mission versus an ISS mission; 2.
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From page 77... ...
THE VIABILITY OF A SHUTTLE MISSION TO HST WHILE MEETING THE CAIB AND NASA RTF REQUIREMENTS Based on NASA briefings and materials supplied by the Space Shuttle program, the following represent the committee's considerations for the viability of a space shuttle mission to HST that will satisfy the CAIB as well as the additional NASA requirements. On-Orbit Inspection Planning and Flexibility An ISS mission incorporates a series of inspections that take advantage of the observations of astronauts on board the ISS as well as the ISS imaging resources to minimize the time required for inspection.
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From page 78... ...
The ultimate objective would be a fully autonomous capability for all shuttle missions in order to address the possibility that an ISS mission fails to achieve the correct orbit, fails to dock successfully, or is damaged during or after undocking. FINDING: A complete inspection of the orbiter thermal protection system can be accomplished on a shuttle servicing mission to HST using the SRMS and the SRMS/OBSS.
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From page 79... ...
FINDING: The orbiter thermal protection system repairs can be accomplished on a shuttle servicing mission to HST following the development of work site and repair techniques for ISS to meet the CAIB and NASA requirements. Safe Haven and Crew Rescue The CAIB did not make a recommendation for a safe haven capability for future space shuttle missions.
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From page 80... ...
Therefore, the earliest the EDO could fly is 2.8 years from project initiation. Space Shuttle Rescue Mission As Integral to All Safe Haven Concepts A shuttle rescue mission is part of the NASA requirements in planning for the ISS mission.
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From page 81... ...
The committee believes that additional work can be done to reduce the time required for implementation of the shuttle HST servicing mission. Repair requirements can be accomplished on an HST mission once work site positioning techniques are developed.
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From page 82... ...
However, the shuttle program has considerable experience in complex spacewalks as described below in "Relevant Space Shuttle Mission Successes." FINDING: The extravehicular activities (spacewalks) for transferring the crew from a damaged vehicle on a shuttle HST flight, although complex, are well within the experience base of the shuttle program.
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From page 83... ...
Although much of the mission planning for a shuttle HST mission was well along prior to the announcement of cancellation of the HST SM-4 mission, additional planning and training for the crew and ground team still remain to be accomplished in order to prepare for the additional activities to meet the CAIB and NASA requirements on the HST mission. As examples, the on-orbit TPS inspection plan would be different from that on an ISS mission.
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From page 84... ...
TIME AND RESOURCES NEEDED TO OVERCOME UNIQUE TECHNICAL OR SAFETY ISSUES ASSOCIATED WITH HST SERVICING After the cancellation of the shuttle HST servicing mission, NASA stopped all work on a non-ISS mission and is concentrating on RTF and the ISS missions. As a result, the NASA data available to the committee to allow it to assess the time and resources required to overcome any unique technical or safety issues associated with HST servicing required to meet the CAIB and NASA requirements was limited to qualitative statements provided by the Shuttle Program Office and other NASA personnel.
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From page 85... ...
The committee agrees that post-RTF missions to the ISS will have some safety advantage over an HST mission, such as total time required to 9NASA, "Review of Hubble Space Telescope Servicing Mission Cost," letter report dated August 13, 2004, NASA, Washington, D.C.
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From page 86... ...
FINDING: The shuttle crew safety risks of a single mission to ISS and a single HST mission are similar and the relative risks are extremely small. RELEVANT SPACE SHUTTLE MISSION SUCCESSES Human Response to Unforeseen On-Orbit Contingencies As noted in "Avionics Reliability Model" in Chapter 4, the flexibility provided by astronauts is highly valuable in repairing unforeseen anomalies in HST's avionics system (see findings in "Avionics Reliability Model")
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From page 87... ...
The crew installed a replacement upper-stage rocket motor while the satellite was in the shuttle payload bay and redeployed it for subsequent successful on-orbit operation.14 Space Shuttle Servicing Missions to the Hubble Space Telescope To date, there have been four completely successful space shuttle servicing missions flown to Hubble. These missions have continuously enhanced the performance of HST, resulting in a huge increase in the data-gathering capability of this observatory.
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From page 88... ...
Both bays contained components requiring thermal protection. There were two documented anomalies during EVAs:16 15 NASA, Space Shuttle Mission Report NSTS-08288, NASA Johnson Space Center, Houston, Tex., February 1994.
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From page 89... ...
, · Installed new outer blanket layers (NOBL) on bays 9 and 10, and 17NASA, STS-103 Space Shuttle Mission Report NSTS-37426, NASA Johnson Space Center, Houston, Tex., February 2000.
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From page 90... ...
Reasons that the shuttle would not be available include loss of a vehicle on a previous flight, or a major anomaly that would ground the shuttle fleet for 6 months or more. The mission risk assessment by this committee is based on the accomplishments of previous shuttle missions involving satellite rescues utilizing EVAs, including the four successful shuttle missions to service HST as discussed in the sections "Human Response to Unforeseen On-Orbit Contingencies" and "Space Shuttle Servicing Missions to the Hubble Space Telescope." In the nine flights considered, the EVA activities resulted in complete mission success in all but one instance, and that case was an unplanned EVA for the unexplained failure of a SYNCOM IV-3 communications satellite to activate on deployment.19 18NASA, STS-109 Space Shuttle Mission Report NSTS-37437, NASA Johnson Space Center, Houston, Tex., May 2002.
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From page 91... ...
FINDING: The risk in the mission phase of a shuttle HST servicing mission is low.
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