Part III-Last Hubble Mission Approaching

Ultimately, when an autonomous inspection and repair capability is implemented, a mission to Hubble will then be as safe as any mission to ISS. Thus, an HST flight requires few, if any, unique capabilities to ensure safe flight beyond those developed for flights to the ISS. NASA plans to provide a Shuttle rescue capability for all flights. The flexibility to schedule SM4 immediately prior to one of the ISS flights provides a ready capability to mount a rescue mission if needed. Risks of micrometeoroid and orbital debris damage to shuttle on ISS flights exceeds that on flights to HST, given the flexibility in the latter to place the shuttle in a protective orientation.

The NASA Administrator has publicly stated “that a Hubble mission would require new and unique procedures that, taken individually, were surmountable but that in the aggregate were risks significantly higher than a shuttle mission to the space station.” The aforementioned data and references from NASA RTF plans demonstrate that this statement cannot be supported. Given that NASA’s plan is to be fully compliant with the CAIB recommendation to develop an autonomous inspection and repair capability, the aggregate risks are higher for ISS flights than for a flight to HST.

When looked at from a TPS survivability perspective, there is a good basis for concluding that HST missions are as safe as or perhaps safer than ISS missions conducted in the same timeframe. HST missions will have:

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