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

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In addition to these software packages, Mission Planning used and developed many internal products:Table 4-3. Mission Planning software developed by GP-BInternally-Developed SoftwareTISISoftware which provides SN and GN schedule visualization, timeline analysis,constraint checking, and reporting. Developed by Mission Planning itself.MP ToolkitAutomation toolkit which automates almost every phase of product delivery.Developed by Mission Planning itself.Timeline ViewerSoftware which provides advanced timeline visualization. Developed by MissionOperations.Command Generation Developed by Lockheed-Martin for the GPB mission, this software compiles thetimeline into spacecraft executable files.Parameter Generation Developed by Lockheed-Martin for the GPB mission, this software maintains adatabase of parameters which configure the spacecraft’s sub-systems.4.2.2.3 Showcase: TISITISI was the keystone software developed by Mission Planning to automate hours-long workflow and toprovide features not available to Mission Planning through any other software available.Early on, it was recognized that Mission Planning didn’t have all the tools it needed to achieve its successcriteria. We faced problems on all fronts of our workflow:Table 4-4. Pre-TISI Mission Planning ChallengesMission Planning Challenges Pre-TISILong Load TimeBuilding a single load was a long process, taking many hours.GenerationSchedule/TimelineSynchronizationSN SchedulingGN SchedulingConstraint CheckingReportsKeeping the spacecraft schedule and the timeline in sync, as both are changing, proveda serious challenge requiring many hours of work, and was prone to human error.The raw work involved in space network scheduling using the SWSI interface madescheduling the number of contacts we required incredibly time consuming, and proneto human error.NASA does not provide any tools to create a properly-formatted GN schedule, and thesewere done by hand. Incredibly prone to human error.Something as simple as making sure we scheduled contacts within proper view periodswas done by hand, and very prone to human error.Our collaborators needed reports in a variety of formats, and all these were assembledby hand. Prone to human error!In short, we faced a lack of tools which made our daily process long and error-prone. TISI was our answer. Itwas created in under 6 months prior to mission launch, and was validated in simulations and ProficiencyExercises. TISI simplified and automated vast stretches of workflow by delivering on a few key design objectives:102 March 2007 Chapter 4 — GP-B On Orbit
Table 4-5. Addressing mission planning needs with TISITISI – Addressing Mission Planning’s NeedsEasy Visualization TISI graphically displays planning data in a customizable viewer which can drill down toany time frame.STK ImportTISI imports data from STK reports, providing it access to all the spacecraft views desired.Visual Scheduling The viewer window is interactive. Scheduling Space and Ground Network passes is a visualexercise, driven by simple clicking.Constraint Checking TISI analyzes both the spacecraft schedule and the current timeline for conformance toconstraint rules.ReportingTISI creates a wide variety of reports, from those used by human operators, to GREAS,WOTIS, and SWSI bulk import formats. These reports are validated and error-free.BlackoutsTISI can provide schedule avoidance through the use of blackout periods. In the case ofGPB, we avoided JPL/DSN views to mitigate a transponder frequency problem.TISI constantly evolved to meet changing needs. Since launch, TISI was upgraded over 30 times to add newfeatures and to make more gains with automation.4.2.2.4 Showcase: Web DeliveryFigure 4-2. Example TISI visualization.Based on the volume and frequency of delivering products to a large number of interested parties, MissionPlanning developed a web-based product delivery system as part of its MP Toolkit. This system replaced apaper-based delivery system which was used in early simulations. The implementation of this system wasinstrumental in automating an entire section of mission planning workflow.Gravity Probe B — Post Flight Analysis • Final Report March 2007 103
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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
Page 80 and 81: A second mass trim operation had be
Page 82 and 83: On Friday, 2 July 2004, the spin ra
Page 84 and 85: Low temperature bakeout was first p
Page 86 and 87: 2.5.1.3 Lockheed Martin Team Phase-
Page 88 and 89: Monthly Highlights of the GP-B Scie
Page 90 and 91: 2.6.1 Overview of the Calibration P
Page 92 and 93: Weekly Highlights of the GP-B Final
Page 94 and 95: 66 March 2007 Chapter 3 — Accompl
Page 96 and 97: It was in this pristine, near-zero
Page 98 and 99: Each quartz rotor is coated with a
Page 100 and 101: Figure 3-3. Functional diagram of a
Page 102 and 103: Based on data from the on-board tel
Page 104 and 105: Ideally, the telescope should have
Page 106 and 107: Figure 3-9. Schematic diagram of st
Page 108 and 109: used. The star trackers are essenti
Page 110 and 111: Result: By using the porous plug, w
Page 112 and 113: Solution: Create a tetrahedral lapp
Page 114 and 115: Constraint 2: The exhaust tube must
Page 116 and 117: Result: The on-orbit gyroscope spin
Page 118 and 119: spacecraft's subsystems for the dur
Page 120 and 121: Constraint 3: Keep the spacecraft p
Page 122 and 123: Technology Category Specific Implem
Page 124 and 125: 96 March 2007 Chapter 4 — GP-B On
Page 126 and 127: Any significant deviation from “g
Page 128 and 129: packages, one for each Ping load an
Page 132 and 133: Table 4-6. Features & benefits of W
Page 134 and 135: This software added considerable ef
Page 136 and 137: It is said that “an experiment is
Page 138 and 139: Table 4-10. Significant Events/Sour
Page 140 and 141: Figure 4-5. Pictorial depiction of
Page 142 and 143: Figure 4-7. Eta-Average Error Assoc
Page 144 and 145: 4.4.4.2 OD Using SLR DataFigure 4-9
Page 146 and 147: 4.4.5 ConclusionsFigure 4-11. Compa
Page 148 and 149: Overall, the storage issues did not
Page 150 and 151: Table 4-11. ITF equipment listEQUIP
Page 152 and 153: 124 March 2007 Chapter 5 — Managi
Page 154 and 155: 5.2 Overview of GP-B Anomalies in O
Page 156 and 157: Figure 5-1. Anomaly Review Team Org
Page 158 and 159: 5.3.3.1 Anomaly Investigation and R
Page 160 and 161: 5.3.5 Anomaly Identification and Re
Page 162 and 163: 5.4.3 Risk Management ApproachThe r
Page 164 and 165: Table 5-1. Summary of Open GP-B ris
Page 166 and 167: 138 March 2007 Chapter 5 — Managi
Page 168 and 169: 140 March 2007 Chapter 6 — The GP
Page 170 and 171: 3. Payload Integration, Testing and
Page 172 and 173: Figure 6-1. Clockwise from top left
Page 174 and 175: MSFC conducted an in-house Phase A
Page 176 and 177: It is important to note that from t
Page 178 and 179: 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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direction (transverse to the space
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9.2.2.2 Spin-up SuspensionDuring sp
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Figure 9-16. Predicted and measured
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Figure 9-18. The GSS passes rotor c
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Figure 9-20. Representative drag-fr
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Table 9-1. GSS Science Mission Mode
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Table 9-3. GSW application source l
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The Design and Testing of the Gravi
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282 March 2007 Chapter 10 — SQUID
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ate uncertainty). Although we have
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All of the GP-B electronics have be
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10.3 Pre-Launch Ground-Based TestsW
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Figure 10-6. AC Magnetic Shielding
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Figure 10-8. Temperature Error of S
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Figure 10-10. Quiescent SQUID Noise
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Analog control loops on the electro
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The science support applications ru
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Table 10-7. SSW application source
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308 March 2007 Chapter 11 — Teles
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Figure 11-1. Block diagram of TRE a
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Additionally, the warm electronics
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Figure 11-3. CLL switch states duri
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Table 11-3. Dates and UTC times whe
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Figure 11-7. Low Gamma Angle Data S
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s N+w i= sign+w i++−+−w i−w i
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expression, which otherwise on a po
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Figure 11-14. Y axis, B side RMS po
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Figure 11-17. X axis, B side curren
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Figure 11-20. Pointing angle differ
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Figure 11-24. Scaled summed current
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Figure 11-26 through Figure 11-29 s
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334 March 2007 Chapter 12 — Cryog
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12.2 Temperature / pressure control
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control the space vehicle without t
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Figure 12-3. Helium flow rate predi
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helium at 1.8 K. It does not appear
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Figure 12-6. Flow meter and ATC flo
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were generally within a day or so o
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shields) and subsequent instability
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350 March 2007 Chapter 12 — Cryog
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352 March 2007 Chapter 13 — Other
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Figure 13-2. ECU-operated heaters i
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13.1.3.1 Vatterfly Valve Operations
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13.1.3.7 Payload MagnetometersThe E
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Figure 13-11. ECU performance durin
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As we entered the second month of o
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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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ReqIDLevel 1CSCSRM Solid StateRecor
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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
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AcronymDefinitionAcronymDefinitionD
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AcronymDefinitionAcronymDefinitionF
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AcronymDefinitionIRUInertial Refere
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AcronymDefinitionAcronymDefinitionM
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AcronymPMPMAPMCPMEPMETPMSPMSUPNPoPO
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AcronymSCMOSCMTSCNSCPASCPMSCRSCSASC
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AcronymDefinitionAcronymDefinitionT
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588 March 2007 Appendix F — Acron
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