GP-B Post-Flight Analysis—Final Report - Gravity Probe B - Stanford ...

“management experiment.” This was one of the first, and largest NASA missions, in which a university was giventhe prime role of managing the development of an entire space flight mission—science instrument, spacecraft,operations and data analysis.Following the Challenger disaster in 1986 and the subsequent closure of NASA's West Coast, polar-orbitingshuttle launch facility, it became necessary to re-cast the GP-B mission as a satellite to be launched from its ownexpendable rocket. From 1992-1994, Stanford conducted a thorough source selection process from which LMSCwas chosen to build the space vehicle into which the dewar and probe would be integrated. During the ensuingyears, Stanford led the combined team, with oversight from NASA's Marshall Space Flight Center (MSFC), indeveloping and perfecting each of the components of the payload and spacecraft.In the late 1990s, it was time to transition GP-B from a research and development program with limited NASAoversight to a classical NASA flight program that would culminate in the complete integration and testing of thepayload-spacecraft system, followed by a successful launch, on-orbit operations, and subsequent data analysis.This shift in focus from maximizing advances in research and development to minimizing the risks in producinga flight-ready spacecraft was a difficult transition for GP-B. It took the exceptional insight and leadership of RexGeveden, then NASA's GP-B Program Manager at MSFC (now Associate Administrator at NASAHeadquarters), in collaboration with Principal Investigator Francis Everitt and other senior management atStanford, LMSC, and NASA to arrive at an effective, minimum-risk-based management plan that would readythe GP-B spacecraft, payload and operations team for the flight mission.Given the success of the GP-B launch and 17.3-month flight mission, the management experiment was also asuccess. It showed that a university, in close partnership with NASA and an experienced aerospace subcontractor,can effectively develop and operate a sophisticated integrated satellite, and it provided NASA withinvaluable management insights for future missions.1.9 The GP-B SpacecraftAll of the Gravity Probe B technologies were integrated into one of the most elegant satellites ever launched(Figure 1-9). The spacecraft was built around the dewar. Embedded along the dewar’s central axis was a cigarshapedcanister called the Probe which contained a series of heat-absorbing windows, a helium-adsorbingcryopump, and the Science Instrument Assembly (SIA)—the pristine space-borne laboratory for making theGP-B experimental measurements.The SIA comprised the telescope and the quartz block, optically bonded together. The quartz block contains thefour gyros and SQUIDs that monitor the spin-axis orientations of the gyros. The telescope and all four gyroswere precisely aligned along the long, central axis of the spacecraft, around which the spacecraft rolledcontinuously at 0.77 rpm (77.5 seconds per revolution) throughout the science phase of the mission.14 March 2007 Chapter 1 — Executive Summary