Hubble Space Telescope Servicing: A Case Study in Analysis and Presentation of Space Program Risk Information
Hwa, Vicky¹; Bearden, David^2
1NASA; ²Aerospace Corporation

Due to safety concerns surrounding the loss of the Space Shuttle Columbia and crew, in early 2004 NASA cancelled the Hubble Space Telescope (HST) Shuttle Servicing Mission 4 (SM4) previously planned for 2005 and embarked on a process to assess other robotic options. This included extending Hubble・s lifetime, as well as understanding the implications of HST・s eventual demise. An analysis was performed with the critical findings that a robotic servicing mission could not be developed in time before HST would lapse into a non-serviceable state, would undertake unprecedented servicing operations and is subject to an aging observatory that may fail for some other reason following servicing. This analysis, which received visibility, scrutiny and interest at high levels of the US Government, culminated in testimony before the National Academy and Congress and contributed to a decision to abandon robotic means and put Shuttle servicing back on the table.

Of perhaps more interest than the findings themselves were the lessons learned from the process undertaken for rapidly defining the trade space, identifying alternatives, assessing risks and communicating them to decision makers. Assessing the value of a given option required an understanding of risks both developmental, a probabilistic expression of the ability to develop and field a desired system before it・s ：need date；, and mission related, the ability to perform as expected and operate safely under nominal conditions. Key to the success of this process was an ability to work closely and transparently with internal and external constituencies with varying agendas and present findings in an effective way to stakeholders at all levels. The intense scrutiny and political sensitivities created a need to structure detailed technical and programmatic data into concrete unassailable findings.

This presentation will review recommended lessons in how to frame analyses of alternatives, identify the full range of alternatives, objectively set criteria and present the material both for senior decision makers who need an accurate condensation as well as sufficient detail for independent review. The combination of reliability modeling and probabilistic schedule assessment into a single measure represents a risk assessment and communication approach that・s broadly applicable to other space programs.