GP-B Post-Flight AnalysisÃ¢Â€Â”Final Report - Gravity Probe B - Stanford ...

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Table 11-3. Dates and UTC times when clamp commands were changedRefer to plots in Figure 11-5. All times listed areconverted from vehicle time to UTC.Left Column Plot 2PT_STxClampPCdA Switched to20-Apr-2004 22:28:29 17614-Jul-2004 15:26:17 17715-Nov-2004 19:13:31 17631-Mar-2005 23:07:52 17728-Jun-2005 16:07:30 178Left Column Plot 3PT_STxClampMCdA Switched to20-Apr-2004 22:28:29 18423-Apr-2004 09:59:09 18522-Jul-2004 19:34:57 18601-Aug-2004 16:32:53 18520-Aug-2004 01:04:13 18606-Nov-2004 23:12:39 18503-Dec-2004 16:48:31 18422-Feb-2005 01:31:39 18504-Mar-2005 00:36:49 18406-Mar-2005 06:15:59 18504-Apr-2005 21:35:42 18606-Jul-2005 18:22:30 187Left Column Plot 5PT_STyClampPCdA Switched to20-Apr-2004 22:28:29 17721-May-2004 08:04:11 17831-Jul-2004 22:38:03 17701-Aug-2004 16:34:13 17919-Nov-2004 17:36:31 17821-Mar-2005 23:53:22 17928-Jun-2005 16:07:30 180Left Column Plot 6PT_STyClampMCdA Switched to20-Apr-2004 22:28:29 18609-Jun-2004 02:45:50 18731-Jul-2004 22:38:53 18601-Aug-2004 16:34:53 18731-Mar-2005 23:08:12 188Right Column Plot 2PT_STxClampPCdBSwitched to20-Apr-2004 22:28:29 16623-Apr-2004 09:59:09 16721-May-2004 08:04:07 16614-Jul-2004 15:27:57 16731-Jul-2004 22:39:13 16601-Aug-2004 16:31:03 16706-Nov-2004 23:13:29 16826-Mar-2005 08:35:32 16926-Mar-2005 20:16:42 16827-Mar-2005 05:12:02 16729-Mar-2005 21:17:32 16930-Mar-2005 23:34:22 168Right Column Plot 3PT_STxClampMCdBSwitched to20-Apr-2004 22:28:29 17814-Jul-2004 15:28:27 17911-Nov-2004 17:34:11 17826-Mar-2005 08:36:12 17926-Mar-2005 20:17:22 17829-Mar-2005 21:17:52 17930-Mar-2005 23:34:52 17812-May-2005 22:54:52 17928-Jun-2005 16:07:30 180Right Column Plot 5PT_STyClampPCdBSwitched to20-Apr-2004 22:28:29 19223-Apr-2004 09:59:09 19114-Jul-2004 15:29:07 19201-Aug-2004 16:33:33 19326-Mar-2005 08:36:33 19226-Mar-2005 20:17:53 19327-Mar-2005 05:12:13 19430-Mar-2005 23:35:13 19328-Jun-2005 08:22:30 194Right Column Plot 6PT_STyClampMCdBSwitched to20-Apr-2004 22:28:29 19723-Apr-2004 09:59:09 19826-Mar-2005 08:37:13 19726-Mar-2005 20:18:33 19827-Mar-2005 05:12:32 19930-Mar-2005 23:35:43 19803-Jun-2005 17:37:30 19921-Jul-2005 18:12:30 200316 March 2007 Chapter 11 — Telescope Readout Subsystem (TRE) Analysis
11.3.4 Daily Data ExampleIt is unusual to look at data for time periods of greater than a few days duration; a 12 or 24 hour time spanfrequently shows many useful and interesting characteristics. Typical data for the TRE includes a look at howwell the temperature control system is working, whether the detector high levels need adjusting, and a look atthe ATC slopes to verify that the guide star is still in the field of view. These plots usually are done for all of theA-side and all of the B-side channels available. Usually the more boring the better, but shown here are two plotsmade from two distinctly different seasons that show how the sun location and the orbit affect the TRE (with theshutter open continuously). Both plots contain the same four signals, with a similar scaling range. The limits aredifferent to accommodate the seasonal difference. The first plot, Figure 11-6, is from 20 August 04 when thegamma angle was near its maximum value. The uncontrolled warm electronics box temperature is at a fewdegrees Celsius and the platform heater is supplying additional heat to the detector platforms during most of theguide star invalid period. During the guide star invalid period, the box warms, due to amplifier saturation, andthen during guide star valid, it cools again. A noticeable slope exists in the detector high level waveform. TheTRE gains were set at gain code 11 for both plots.Figure 11-6. High Gamma Angle Data SampleThe second plot, Figure 11-7, is from 12 February 05 when the gamma angle was near its minimum. The heatervoltage shows only small blips at the beginning and end of guide star invalid, the box temperature is near 15 °Cwith much smaller excursions, and the detector high levels show much less sloping.Gravity Probe B — Post Flight Analysis • Final Report March 2007 317
Page 1 and 2:
Post Flight Analysis — Final Repo
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Signatures & ApprovalsPrepared byPu
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Table of ContentsPreface . . . . .
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6.8 Sources and References . . . .
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11 Telescope Readout Subsystem (TRE
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14 Data Collection, Processing & An
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xiv March 2007 Table of Contents
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Figure 3-4. The GP-B dewar—one of
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Figure 8-5. The Seasons of GP-B . .
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Figure 11-20. Pointing angle differ
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Figure 14-9. In the Anomaly Room, t
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xxiv March 2007
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Table 13-3. GP-B payload magnetomet
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xxviiiMarch 2007
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2 March 2007 Chapter 1 — Executiv
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facility, it was necessary to recas
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spacetime around with them as they
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After years of work and the inventi
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axis of a gyroscope rotor changes i
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Figure 1-8. Clockwise, from top lef
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“management experiment.” This w
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Attitude-Control Gyroscopes. Two pa
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Any significant deviation from “g
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established, ranging from Level 1 (
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1.14 The Broader Legacy of GP-BAt l
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24 March 2007 Chapter 2 — Overvie
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Figure 2-1. GP-B Historical Time Li
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Applied Physics Laboratory, of the
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William Fairbank once remarked: “
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In Einstein’s view, space and tim
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y a mere 1.1 inches. You can see th
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Figure 2-10. Schematic diagram of t
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Figure 2-12. Final assembly of the
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Sun Shield. The sun shield is a lon
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2.1.8 The Broader Legacy of GP-BWhe
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2.3 Spacecraft SeparationThe Solar
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Flight Anomalies.) Furthermore, a d
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Table 2-2. Weekly summary of IOC ac
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2.4.3.2 Guide Star AcquisitionAbout
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A second mass trim operation had be
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On Friday, 2 July 2004, the spin ra
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Low temperature bakeout was first p
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2.5.1.3 Lockheed Martin Team Phase-
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Monthly Highlights of the GP-B Scie
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2.6.1 Overview of the Calibration P
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Weekly Highlights of the GP-B Final
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66 March 2007 Chapter 3 — Accompl
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It was in this pristine, near-zero
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Each quartz rotor is coated with a
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Figure 3-3. Functional diagram of a
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Based on data from the on-board tel
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Ideally, the telescope should have
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Figure 3-9. Schematic diagram of st
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used. The star trackers are essenti
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Result: By using the porous plug, w
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Solution: Create a tetrahedral lapp
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Constraint 2: The exhaust tube must
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Result: The on-orbit gyroscope spin
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spacecraft's subsystems for the dur
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Constraint 3: Keep the spacecraft p
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Technology Category Specific Implem
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96 March 2007 Chapter 4 — GP-B On
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Any significant deviation from “g
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packages, one for each Ping load an
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In addition to these software packa
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Table 4-6. Features & benefits of W
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This software added considerable ef
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It is said that “an experiment is
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Table 4-10. Significant Events/Sour
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Figure 4-5. Pictorial depiction of
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Figure 4-7. Eta-Average Error Assoc
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4.4.4.2 OD Using SLR DataFigure 4-9
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4.4.5 ConclusionsFigure 4-11. Compa
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Overall, the storage issues did not
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Table 4-11. ITF equipment listEQUIP
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124 March 2007 Chapter 5 — Managi
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5.2 Overview of GP-B Anomalies in O
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Figure 5-1. Anomaly Review Team Org
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5.3.3.1 Anomaly Investigation and R
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5.3.5 Anomaly Identification and Re
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5.4.3 Risk Management ApproachThe r
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Table 5-1. Summary of Open GP-B ris
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138 March 2007 Chapter 5 — Managi
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140 March 2007 Chapter 6 — The GP
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3. Payload Integration, Testing and
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Figure 6-1. Clockwise from top left
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MSFC conducted an in-house Phase A
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It is important to note that from t
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6.3.1 Incremental PrototypingThe pe
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alignment, and act as an accelerome
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Figure 6-9. The Lockheed Martin GP-
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Furthermore, a fourth electronic sy
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positive thermal connections betwee
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astrophysics/cosmology. Many of the
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Figure 6-10. MSFC Program Managers/
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As described in Chapter 2, the flig
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6.7 Some Observations on the Manage
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168 March 2007 Chapter 6 — The GP
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170 March 2007 Chapter 7 — Attitu
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7.1.2 Vehicle ATC ModesThere are es
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The output of the pressure transduc
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Figure 7-3. Science Telescope Compo
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Figure 7-5. Pitch and Yaw Pointing
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Figure 7-7. Magnitude of the roll r
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Changing the method by which the gy
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7.3.3 Drag-Free Control SystemFigur
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7.3.3.1 DFS - PerformanceThe GP-B d
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Figure 7-15. Mass flow effects of a
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7.5.2 Successful recovery from mult
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If the vehicle control system were
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accomplish this, the ARPs are mount
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7.5.6.1 South Atlantic AnomalyProto
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Figure 7-23. Effects on telescope p
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200 March 2007 Chapter 7 — Attitu
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202 March 2007 Chapter 8 — Other
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Figure 8-2. Block Diagram of CDH co
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8.1.1.4 WATCH DOG TIMERFigure 8-4.
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of eclipses each day (approximately
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Figure 8-8. GSS1 Temperature Trends
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Figure 8-10. Forward Dewar Vacuum S
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The Gravity Probe B spacecraft has
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Figure 8-13. Forward -X Thruster Te
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gaFigure 8-15. Aft -X Thruster Temp
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Because there are only two SQUID br
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Because the specifications for SRE
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8.3.2 Critical Mission RequirementT
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Figure 8-19 is a plot of the power
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Battery Performance Summary:Figure
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Figure 8-23. Solar Array Temperatur
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8.3.10 ConclusionThe electrical pow
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8.4.1 TDRSS OperationsFigure 8-28.
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Figure 8-30. Xpndr-A STDN (green),
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Figure 8-32. Plot of TDRS AGC vs Te
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The FSW also met its subsystem leve
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Appendix E, Flight Software Applica
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Table 8-4. SCRs Addressed in On-orb
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The software and macro changes resu
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Figure 8-38 below is an excerpt fro
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Figure 8-40. A-side CCCA Single Bit
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Figure 8-43. A-side CCCA Single Bit
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When single MBEs did not result in
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256 March 2007 Chapter 9 — Gyro S
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9.1 GSS Hardware DescriptionFigure
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significantly reduces and thus pres
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9.1.11 Clock synchronizationThe aft
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Figure 9-8. Block diagram of the LQ
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Page 296 and 297: 9.2.2.2 Spin-up SuspensionDuring sp
Page 298 and 299: Figure 9-16. Predicted and measured
Page 300 and 301: Figure 9-18. The GSS passes rotor c
Page 302 and 303: Figure 9-20. Representative drag-fr
Page 304 and 305: Table 9-1. GSS Science Mission Mode
Page 306 and 307: Table 9-3. GSW application source l
Page 308 and 309: The Design and Testing of the Gravi
Page 310 and 311: 282 March 2007 Chapter 10 — SQUID
Page 312 and 313: ate uncertainty). Although we have
Page 314 and 315: All of the GP-B electronics have be
Page 316 and 317: 10.3 Pre-Launch Ground-Based TestsW
Page 318 and 319: Figure 10-6. AC Magnetic Shielding
Page 320 and 321: Figure 10-8. Temperature Error of S
Page 322 and 323: Figure 10-10. Quiescent SQUID Noise
Page 324 and 325: Analog control loops on the electro
Page 326 and 327: The science support applications ru
Page 328 and 329: Table 10-7. SSW application source
Page 336 and 337: 308 March 2007 Chapter 11 — Teles
Page 338 and 339: Figure 11-1. Block diagram of TRE a
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Page 360 and 361: Figure 11-26 through Figure 11-29 s
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Page 364 and 365: 12.2 Temperature / pressure control
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Page 368 and 369: Figure 12-3. Helium flow rate predi
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Page 372 and 373: Figure 12-6. Flow meter and ATC flo
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Page 378 and 379: 350 March 2007 Chapter 12 — Cryog
Page 380 and 381: 352 March 2007 Chapter 13 — Other
Page 382 and 383: Figure 13-2. ECU-operated heaters i
Page 384 and 385: 13.1.3.1 Vatterfly Valve Operations
Page 386 and 387: 13.1.3.7 Payload MagnetometersThe E
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Page 392 and 393: During the last month of IOC, prepa
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Figure 13-19. ECU heater activity d
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Table 13-1. Proton monitor channel
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Figure 13-21. Proton Monitor data i
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In November, 2004 there was a large
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Figure 13-28 shows a correlation th
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13.3.1 About the MagnetometersFigur
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13.3.2 Other Applications for Paylo
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Figure 13-35. GPS Antennae Field of
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Figure 13-37. Master Antenna Switch
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Figure 13-39. Time difference betwe
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13.4.6 On-Orbit ResultsThe GPS comp
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and velocity values erroneously cal
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E. G. Lightsey, C. E. Cohen, B. W.
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Figure 13-45. A Bottom View of the
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Figure 13-48. The GMA configuration
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Table 13-10. Summary for Helium Gas
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398 March 2007 Chapter 14 — Data
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a relatively slow data rate, so we
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Figure 14-4. NASA ground stations a
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electronic components to recover fr
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By a process of elimination, the GP
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A special room in the GP-B Mission
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Starting on 3 December 1725, Bradle
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seemed that aberration of starlight
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14.1.6 Telescope Dither—Correlati
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14.1.6.3 The Telescope Dither Patte
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amplifications. Thus, in addition t
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14.2.2 Independent Data Analysis Te
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monthly time scales. Though only sh
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424 March 2007 Chapter 15 — Preli
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Figure 15-2. A diagram of the GP-B
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15.4 The Two Surprises and Their Im
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Near Zeroes.) The exception that we
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Figure 15-8. A slide from the GP-B
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Figure 15-9. A poster on the effect
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electrostatic patches, located at o
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Last summer (2006), Mac Keiser devi
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440 March 2007 Chapter 15 — Preli
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442 March 2007 Chapter 16 — Lesso
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16.1.1.3 Flight science downlink da
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Description of the GP-B experience:
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Lessons:1. Perform all tests with a
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Figure 16-1. Six interacting transl
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16.1.3.2 Training and certification
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Below is an edited summary of six a
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460 March 2007 Chapter 16 — Lesso
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462 March 2007 Appendix A — Gravi
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Apogee altitude659.1 km (409.6 mile
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466 March 2007 Chapter B — Spacec
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Gravity Probe B — Post Flight Ana
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470 March 2007 Appendix C — Weekl
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16 April 2004—Vehicle is Prepared
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The electrical power system is full
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4 JUNE 2004—MISSION UPDATE: DAY 4
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SQUIDs to detect their rotation spe
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17 JULY 2004—MISSION UPDATE: DAY
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indicate that we have reduced the t
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C.4 Science Mission Phase: 8/27/04
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• GP-B also has an independent da
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free suspension parameters to de-tu
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We have received inquiries about a
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One of the effects of geomagnetic s
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egan transmitting, one-by-one, stat
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28 JANUARY 2005—GRAVITY PROBE B M
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magnetic pole. This event triggered
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8 APRIL 2005—GRAVITY PROBE B MISS
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On Tuesday afternoon (19-April), GP
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Norway or through the NASA space ne
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Dewar Temperature: 1.82 kelvin, hol
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visitors on a tour of the GP-B faci
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test, we are planning on running fi
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contractor at the Goddard Space Fli
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On Wednesday, we visited the star H
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Gyro Suspension System (GSS): All 4
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The helium in the dewar has now sur
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the all the spacecraft status data.
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522 March 2007 Appendix D — Summa
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Figure D-2 below shows the distribu
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DateSeveritySubtypeTitle Descriptio
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DateSeverity24 26-Apr-04 Obs F Nois
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DateSeverity40 11-May-04 Obs T Dwel
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DateSeverity68 16-Jun-04 Medium Dec
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DateSeverity84 13-Jul-04 Obs F Slig
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DateSeverity116 26-Sep-04 Obs F SG3
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DateSeverity132 20-Dec-04 Obs F Unc
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DateSeverity149 5-Mar-05 Obs T Few
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DateSeverity169 04-Jun-05 Obs F MBE
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DateSeverity191 04-Oct-05 Obs A GSS
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550 March 2007 Appendix E — Fligh
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ReqIDLevel 1CSCDMP DataMgmtProcessi
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ReqIDLevel 1CSCLevel2 CSC Level 3 C
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Page 586 and 587:
Page 588 and 589:
ReqIDLevel 1CSCSRM Solid StateRecor
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Page 592 and 593:
Page 594 and 595:
ReqIDLevel 1CSCSRP SafemodeResponse
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ReqIDLevel 1CSCGUP GSS Processing g
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570 March 2007 Appendix F — Acron
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AcronymDefinitionAcronymDefinitionB
Page 602 and 603:
AcronymDefinitionAcronymDefinitionD
Page 604 and 605:
AcronymDefinitionAcronymDefinitionF
Page 606 and 607:
AcronymDefinitionIRUInertial Refere
Page 608 and 609:
AcronymDefinitionAcronymDefinitionM
Page 610 and 611:
AcronymPMPMAPMCPMEPMETPMSPMSUPNPoPO
Page 612 and 613:
AcronymSCMOSCMTSCNSCPASCPMSCRSCSASC
Page 614 and 615:
AcronymDefinitionAcronymDefinitionT
Page 616:
588 March 2007 Appendix F — Acron
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