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

test, we are planning on running final calibrations from August 15 toSeptember 1, 2005. If any time remains after that, further calibrationswill be performed at a different roll rate.12 AUGUST 2005—GRAVITY PROBE B MISSIONUPDATEMission Elapsed Time: 479 days (68 weeks/1.31 years)Science Data Collection: 350 days (51 weeks/11.51 months)Current Orbit #: 7,006 as of 1:00 PM PSTSpacecraft General Health: GoodRoll Rate: Normal at 0.7742 rpm (77.5 seconds per revolution)Dewar Temperature: 1.82 kelvin, holding steadyCommand & Data Handling (CDH): B-side (backup) computer incontrol, Multi-bit errors (MBE): 0, Single-bit errors (SBE): 7 (dailyaverage)With nearly a full year of science data captured, the mission isproceeding well. This past week, we made some routine adjustmentsduring our final week of nominal science data collection. Theseadjustments included updating the star tracker star magnitudes,running an SRE calibration (SQUID Readout Electronics), updatingthe control gyro z-bias, and power cycling the ECU (ElectronicsControl Unit).On Monday, August 15th, we will begin the final calibration phase ofthe mission. In this phase, we will be maneuvering the spacecraft tonearby stars and then back to the guide star to calibrate the GyroscopeSuspension System (GSS). This phase will last two weeks, endingaround August 29th. If any helium remains, further calibrations willbe performed at a different vehicle roll rate. Because of the nature ofthese calibrations, the science (data gathering) phase of the missionwill end as soon as we begin these calibrations. By that point, we willhave collected 352 days (or 11.5 months) of science data—a greatsuccess!Note: During this final calibration phase, our weekly updates will belimited to the Mission Director's Summary, as our communicationsand public affairs team members will be concentrating their efforts onour End-of-Mission activities and our final report to NASA.510 March 2007 Appendix C — Weekly Chronicle of the GP-B Mission