HUBBLE SPACE TELESCOPE SERVICING: A CASE STUDY IN ANALYSIS ANDPRESENTATION OF SPACE PROGRAM RISK INFORMATION

摘要

NASA requested that The Aerospace Corporationrnperform a nonadvocate assessment of Hubble SpacernTelescope (HST) robotic servicing alternatives. Thesernalternatives encompassed a broad range of options in thernfollowing families: ground life extension, disposal,rnrehosting instrumentation on other platforms, roboticrnservicing, and the baseline Shuttle Servicing Mission 4rn(SM4) previously planned for 2005. In developing thisrnanalyses of alternatives (AoA), Aerospace assessed eachrnalternative against a set of measures of effectivenessrn(MOEs), which included cost, schedule, risk, and thernresulting capability of the alternative to perform sciencernrelative to the planned post-SM4 baseline.rnThe key findings of this AoA are:rn1. Ground-based life extension does not replacerninstruments and does not address the riskrnassociated with uncontrolled HST reentry.rn2. Disposal-only alternatives have relatively lowrncost, but provide no HST life extension orrnadded science capability comparable to therncurrent configuration.rn3. Rehost alternatives provide higher value atrnequivalent cost to the robotic servicingrnmissions, but may result in a two- to sevenyearrnscience gap. This higher value resultsrnfrom the lower development and mission risks.rn4. Robotic servicing alternatives, based onrnestimated development schedules, arernsusceptible to arriving too late. HST may nornlonger be in a serviceable state. Furthermore,rnthey are subject to an aging observatory thatrnmay fail for some other reason during the threernyears following servicing.rn5. SM4 has costs in the same range as the rehostrnand robotic servicing alternatives, has higherrnprobability of mission success than the roboticrnservicing missions, and does not suffer fromrnthe gap in science associated with rehostrnalternatives.1 Other means to perform SM4 with reduced risk by launching a safe habitat orrnrelocating HST to the vicinity of thernInternational Space Station (ISS) werernexamined, but would require morerndevelopment time and be more costly.