Development of the Gravity Probe B flight mission

Turneaure, J. P.; Everitt, C. W. F.; Parkinson, Bradford W.; Bardas, D.; Buchman, Saps; DeBra, D.; Dougherty, H.; Gill, D.; Grammer, J. R.; Green, G.B.; Gutt, G.M.; Gwo, Dz‐Hung; Heifetz, M.; Kasdin, N. Jeremy; Keiser, G. M.; Lipa, J. A.; Lockhart, J. M.; Mester, John; Muhlfelder, B.; Parmley, Richard T.; Silbergleit, A. S.; Sullivan, Mark; Taber, M.; Patten, R. A. van; Vassar, R.; Wang, S.; Xiao, Y. M.; Zhou, Ping

doi:10.1016/s0273-1177(03)90351-6

Cited by 16 publications

(6 citation statements)

References 10 publications

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“…The assembled dewar (flight dewar, vacuum probe, SIA, and other items), called the payload [34], was transported to Lockheed-Martin, where it was integrated with the spacecraft to form the space vehicle. At Lockheed-Martin, electronics were installed allowing flight-like commanding and telemetry via radio frequency communication.…”

Section: Flight Gyroscope Ground Test Programmentioning

confidence: 99%

The Gravity Probe B gyroscope

Buchman¹,

Lipa²,

Muhlfelder³

et al. 2015

Class. Quantum Grav.

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The Gravity Probe B (GP-B) gyroscope, a unique cryogenically operated mechanical sensor, was used on-orbit to independently test two predictions of general relativity (GR). Here, we describe the development and performance of the GP-B gyroscope, its geometry and fabrication, spin-up and vacuum approach, magnetic considerations, and static charge management. The history of electrically suspended gyroscopes puts the current work in context. Fabrication and ground testing of the GP-B gyroscope are detailed, followed by a review of on-orbit initialization, calibration, operation, and performance. We find that the performance was degraded relative to the mission goals, but was still sufficient to provide excellent new tests of GR. The degradation is partially due to the existence of gyroscope torques due to an unanticipated interaction between patch potentials on the rotor and the housing. We discuss these patch potentials and describe the effect of related torques on gyro drift. It was essential to include models for the effects due to the patch potentials in the complete data analysis model to yield determinations of the two GR effects.

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Section: Flight Gyroscope Ground Test Programmentioning

confidence: 99%

The Gravity Probe B gyroscope

Buchman¹,

Lipa²,

Muhlfelder³

et al. 2015

Class. Quantum Grav.

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“…A recent, preliminary, comparison of a simplified GEANT4 simulation and actual GP-B charging rates, indicate 45% agreement (GP-B simulation is larger than experimental value by 45%), reinforcing confidence in these predictions. 18,19 The ASTROD I acceleration noise limit is 10 −13 ms −2 Hz −1/2 at 0.1 mHz, which is less stringent than the LISA requirement. The magnitudes of the Coulomb and Lorentz acceleration noise associated with test mass charging increase with decreasing frequency.…”

Section: Resultsmentioning

confidence: 99%

Further Test Mass Charging Simulations for Astrod I

Bao

Shaul

et al. 2008

Int. J. Mod. Phys. D

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The electrostatic charging of the test mass in ASTROD I (Astrodynamical Space Test of Relativity using Optical Devices I) mission can affect the quality of the science data as a result of spurious Coulomb and Lorentz forces. To estimate the size of the resultant disturbances, credible predictions of charging rates and the charging noise are required. Using the GEANT4 software toolkit, we present a detailed Monte Carlo simulation of the ASTROD I test mass charging due to exposure of the spacecraft to galactic cosmicray (GCR) protons and alpha particles ( 3 He, 4 He) in the space environment. A positive charging rate of 33.3 e + /s at solar minimum is obtained. This figure reduces by 50% at solar maximum. Based on this charging rate and factoring in the contribution of minor cosmic-ray components, we calculate the acceleration noise and stiffness associated with charging. We conclude that the acceleration noise arising from Coulomb and Lorentz effects are well below the ASTROD I acceleration noise limit at 0.1 mHz both at solar minimum and maximum. The coherent Fourier components due to charging are investigated, it needs to be studied carefully in order to ensure that these do not compromise the quality of science data in the ASTROD I mission.

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“…The GP-B readout system provides measurements of the time-varying angle between the direction of the gyroscope spin axis aligned with the London moment (Turneaure et al 2003;Everitt et al 2008), and the SQUID pick-up loop that rolls with the S/C. The corresponding measurement model is shown, to lowest order, to be (Silbergleit 2006):…”

Section: Measurement Modelmentioning

confidence: 99%

The Gravity Probe B Data Analysis Filtering Approach

et al. 2009

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A simple pre-flight strategy of the Gravity Probe B (GP-B) data analysis has evolved in the elaborate multi-level structure after the discovery of the complex polhode motion, and of the patch effect torques. We describe a cascade of estimators (filters) that reduce the science data (SQUID and telescope signals) to the estimates of the relativistic drift rates. Those estimators, structured in two "floors", are based on the polhode-related models for the readout scale factor and patch effect torque. Results of the 1 st Floor processinggyro orientation profiles-manifest clearly the strong geodetic effect but also the presence of classical torque. Modeling of the patch effect torque at the 2 nd Floor provides a successful compensation of the torque contributions, and leads to consistent estimates of the relativistic drift rates.

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Development of the Gravity Probe B flight mission

Cited by 16 publications

References 10 publications

The Gravity Probe B gyroscope

The Gravity Probe B gyroscope

Further Test Mass Charging Simulations for Astrod I

The Gravity Probe B Data Analysis Filtering Approach

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