Time Transfer Between UTC and Local Vehicle Time for the Gravity Probe B Relativity Mission

Jie Li, George M. Keiser, James M. Lockhart and Paul Shestople

Abstract:	The NASA/Stanford Gravity Probe B (GP-B) Mission is a satellite experiment designed to test Einstein’s Theory of General Relativity. The GP-B satellite was successfully launched into orbit at 9:57:24 AM PDT on April 20, 2004. In addition to accurate measurements, accurate timing of signals is critical to the GP-B mission. It is required that the effective sample time of all science signals of GP-B shall be known relative to Coordinated Universal Time (UTC) to an accuracy of less than 0.1 millisecond after ground processing. This paper discusses the time transfer between UTC and local vehicle time of the GP-B satellite. The timing system onboard the GP-B satellite is introduced and the algorithm of ground processing of the telemetry timing data is presented. Clock models are compared regarding complexity, flexibility and accuracy of the timing data processing. Data from the space flight and ground tests demonstrate that the time conversion between UTC and vehicle time is achieved to an accuracy of several microseconds, an order of magnitude better than the requirement of the GP-B mission.
Published in:	Proceedings of the 60th Annual Meeting of The Institute of Navigation (2004) June 7 - 9, 2004 Dayton Marriott Hotel Dayton, OH
Pages:	560 - 570
Cite this article:	Li, Jie, Keiser, George M., Lockhart, James M., Shestople, Paul, "Time Transfer Between UTC and Local Vehicle Time for the Gravity Probe B Relativity Mission," Proceedings of the 60th Annual Meeting of The Institute of Navigation (2004), Dayton, OH, June 2004, pp. 560-570.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In