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

Figure 3-4. The GP-B dewar—one of the largest and most sophisticated dewars ever flown . . . . . . . . . . . . . . . .72Figure 3-5. Cross sectional schematic of the dewar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73Figure 3-6. Proportional micro thrusters used for GP-B spacecraft attitude control . . . . . . . . . . . . . . . . . . . . . . . . . .74Figure 3-7. A pre-flight prototype of the Cassegrain telescope on-board the GP-B spacecraft . . . . . . . . . . . . . . .75Figure 3-8. Tracking the guide star, IM Pegasi, with the GP-B telescope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76Figure 3-9. Schematic diagram of starlight image division in the GP-B telescope . . . . . . . . . . . . . . . . . . . . . . . . . . .78Figure 3-10. The porous plug . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81Figure 3-11. Lead bag magnetic shield in GP-B flight probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82Figure 3-12. GP_B proportional micro thruster assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83Figure 3-13. Polishing a gyro rotor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .83Figure 3-14. Measuring the roundness of a gyro rotor and mapping the contours on its surface . . . . . . . . . . . . . .84Figure 3-15. A gyro rotor and both halves of its quartz housing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85Figure 3-16. Top view of the Gas Management Assembly (GMA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85Figure 3-17. The telescope Image Divider Assembly (IDA) and Detector Package Assemblies (DPA) . . . . . . . . . .86Figure 3-18. Schematic diagram and photo of a SQUID gyro readout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87Figure 3-19. Checking the GP-B solar arrays on the spacecraft at Lockheed Martin & solar arrays deployed on ascale model of the spacecraft . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88Figure 3-20. GP-B’s annual orientation patterns with respect to the sun . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89Figure 3-21. Window #4—the outer vacuum seal of the Probe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90Figure 3-22. GP-B—The first spacecraft with 6 degrees of freedom in position and attitude control . . . . . . . . . .91Figure 4-1. NASA GP-B Program Manager, Tony Lyons, from the Marshall Space Flight Center in Huntsville, AL,presents a NASA Group Achievement Award to the entire GP-B team in November 2005. . . . . . . .98Figure 4-2. Example TISI visualization. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103Figure 4-3. Number of hours of re-planning required per day during IOC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105Figure 4-4. Data flow through the GP-B’s automated data processing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109Figure 4-5. Pictorial depiction of η. The circle represents the Earth, the vertical line is the orbit plane viewededge-on, and the asterisk represents the guide star. η is the angle between orbit plane andguide star at any point in the orbit plane. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112Figure 4-6. Eta and Eta-Average Histories (Degrees) Associated with GP-B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113Figure 4-7. Eta-Average Error Associated with GP-B Orbit as a function of IOC duration and sciencemission lifetime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114Figure 4-8. Usable GPS Points per Day (2005) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115Figure 4-9. Typical residual plot from daily GPS solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116Figure 4-10. SLR passes per day . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117Figure 4-11. Comparison of GPS and SLR Cross-Track Errors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118Figure 4-12. GP-B Computer Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119Figure 4-13. The Integrated Test Facility (ITF) flight simulator hardware in a Clean Room at Lockheed Martin . .122Figure 5-1. Anomaly Review Team Organization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128Figure 5-2. GP-B Anomaly Room Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131Figure 5-3. For each risk, an assessment is completed by the identifying team or person . . . . . . . . . . . . . . . . . . 134Figure 5-4. Metric of risk item closure prior to launch of GP-B. All risk items were either acceptedor closed prior to launch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135Figure 5-5. (part 1 or 3). Open risk items during on-orbit science mission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136Figure 5-6. (part 2 or 3). Open risk items during on-orbit science mission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137Figure 5-7. (part 3 or 3). Open risk items during on-orbit science mission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137Figure 6-1. Clockwise from top left: GP-B Co Founders Leonard Schiff, William Fairbank, and Robert Cannon andformer head of NASA's Office of Space Sciences, Nancy Roman. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144Figure 6-2. Clockwise from top left: GP-B Principal Investigator, Francis Everitt and Co-PIsBradford Parkinson, John Turneaure and Dan DeBra. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147xvi March 2007