Gravity Probe B data analysis status and potential for improved accuracy of scientific results

Abstract

Gravity Probe B (GP-B) is a landmark physics experiment in space designed to yield precise tests of two fundamental predictions of Einstein's theory of general relativity, the geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth orbit. Launched on 20 April 2004, data collection began on 28 August 2004 and science operations were completed on 29 September 2005 upon liquid helium depletion. During the course of the experiment, two unexpected and mutually-reinforcing complications were discovered: (1) larger than expected ‘misalignment’ torques on the gyroscopes producing classical drifts larger than the relativity effects under study and (2) a damped polhode oscillation that complicated the calibration of the instrument's scale factor against the aberration of starlight. Steady progress through 2006 and 2007 established the methods for treating both problems; in particular, an extended effort from January 2007 on ‘trapped flux mapping’ led in August 2007 to a dramatic breakthrough, resulting in a factor of ∼20 reduction in data scatter. This paper reports results up to November 2007. Detailed investigation of a central 85-day segment of the data has yielded robust measurements of both relativity effects. Expansion to the complete science data set, along with anticipated improvements in modeling and in the treatment of systematic errors may be expected to yield a 3–6% determination of the frame-dragging effect.

Spin in stationary gravitational fields and rotating frames

“…Putting ξ = 0, thus specifying to the Schwinger tetrad, we find that the classical formula (49) perfectly reproduces the quantum result (27). The extra Lorentz factor is due to the fact that the classical evolution of spin was measured by using the proper time τ, whereas the quantum evolution was analyzed by using the coordinate time t. If we choose another tetrad by putting ξ = 1/2 in (50), the equation (49) yields the result by Pomeransky and Khriplovich [3] and Dvornikov [4]:…”

“…This effect is currently analyzed in the Gravity Probe B experiment [26,27]. However, relativistic corrections to the LT effect manifest neither in this experiment nor in other experiments inside the solar system [28].…”

The Flyby Anomaly in an Extended Whitehead’s Theory

“…A consequence of this mathematical similarity is that Whitehead's theory makes the same predictions as Einstein's GR for the so-called classical tests: the bending of stellar light rays grazing the surface of the Sun, the anomalous advance of Mercury's perihelion and gravitational redshift [2]. On the other hand, Shapiro's echo delay [6] and the most recent test for the geodetical and gravitomagnetic precession of orbiting superconducting gyroscopes transported by the Gravity Probe B [7,8] are also in agreement with Whitehead's theory, as well as GR [10].…”

Influence of geomagnetic field on the motion of low satellites

“…In our opinion the variation of electric charge may have some effects on the GPB since it is a massive and large craft; hence it needs a more detailed study, considering the real shape and size of the craft in a future study. Also it was mentioned that it is required to have a better understanding of all the more disturbing effects on GPB (Everitt et al 2008).…”