Abstract
Magnetic field trapped in the Gravity Probe B (GP-B) gyroscope rotors contributes to the scale factor of the science readout signal. This contribution is modulated by the rotor’s polhode motion. In orbit, polhode period was observed to change due to a small energy dissipation, which significantly complicates data analysis. We present precise values of spin phase, spin down rate, polhode phase and angle, and scale factor variations obtained from the data by Trapped Flux Mapping. This method finds the (unique) trapped field distribution and rotor motion by fitting a theoretical model to the harmonics of high (gyroscope spin) frequency signal. The results are crucial for accurately determining the gyroscope relativistic drift rate from the science signal.
Similar content being viewed by others
References
R.J. Adler, A.S. Silbergleit, Int. J. Theor. Phys. 39(5), 1287 (2000)
B.M. Barker, R.F. O’Connell, Phys. Rev. D 11(4), 711 (1975)
S. Buchman, D.K. Gill, Evidence for Patch Effect Forces on the Gravity Probe B Gyroscopes, APS Meeting, April 2007. Abstract: Bulletin of the APS, 52(3) (2007)
J.W. Conklin, Estimation of the Mass Center and Dynamics of a Spherical Test Mass for Gravitational Reference Sensors. Ph.D. Thesis, Aero/Astro, Stanford University (Stanford, 2009)
M. Dolphin, Polhode Dynamics and Gyroscope Asymmetry Analysis on Gravity Probe B Using Gyroscope Position Data. Ph.D. Thesis, Aero/Astro, Stanford University (Stanford, 2007)
T.G. Duhamel, Contributions to the Error Analysis in the Relativity Experiment. Ph.D. Thesis, Aero/Astro, Stanford University (Stanford, 1984)
N.A. Egarmin, Mech. Solids 15, 33 (1980)
C.W.F. Everitt, W.W. Fairbank, D.B. DeBra et al., Report on a Program to Develop a Gyro Test of General Relativity in a Satellite and Associated Control Technology. HEPL, Aero/Astro, Stanford University (Stanford, 1980)
C.W.F. Everitt, M. Adams, W. Bencze et al., Space Sci. Rev. (2009, this issue) (Chap. 1 of this report)
M. Heifetz, W. Bencze, T. Holmes et al., Space Sci. Rev. (2009, this issue) (Chap. 4 of this report)
G.M. Keiser, B. Cabrera, in Proc. of The National Aerospace Meeting (The Institute of Navigation, Washington, 1983)
G.M. Keiser, J. Kolodziejczak, A.S. Silbergleit, Space Sci. Rev. (2009, this issue) (Chap. 3 of this report)
G.M. Keiser, A.S. Silbergleit, Pick-up Loop Symmetry and Centering. Gravity Probe B document S0243 (Stanford University, Stanford, 1991)
J.A. Kozaczuk, Precise Determination of the Spin Speed and Spin Down Rate of Gravity Probe B Gyroscopes. Physics Honor Thesis, Stanford University (Stanford, 2007)
J. Lagarias et al., SIAM J. Optim. 9(1), 112 (1998)
L.D. Landau, E.M. Lifshitz, Mechanics (Pergamon, Elmsford, 1959)
F. London, Superfluids, vol. 1 (Dover, New York, 1961)
W.D. MacMillan, Dynamics of Rigid Bodies (Dover, New York, 1960)
V.J. Modi, J. Spacecr. Rockets 11, 743 (1973)
I.M. Nemenmann, A.S. Silbergleit, J. Appl. Phys. 86(1), 614 (1999)
M.E. Rose, Elementary Theory of Angular Momentum (Dover, New York, 1995)
M. Salomon, Properties of Gravity Probe B Gyroscopes Obtained from High Frequency SQUID Signal. Ph.D. Thesis, Aero/Astro, Stanford University (Stanford, 2008)
J.P. Turneaure, C.W.F. Everitt, B.W. Parkinson et al., Adv. Space Res. 32(7), 1387 (2003)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Silbergleit, A., Conklin, J., DeBra, D. et al. Polhode Motion, Trapped Flux, and the GP-B Science Data Analysis. Space Sci Rev 148, 397–409 (2009). https://doi.org/10.1007/s11214-009-9548-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11214-009-9548-z