Title: Gravity Probe B: On Orbit


The Gravity Probe B experiment was developed to test two predictions of General Relativity, the geodetic and the frame-dragging precessions of a mechanical gyroscope due to the gravitational field of the Earth. This cryogenic experiment was carried into orbit on April 20, 2004 by a Boeing Delta II rocket. On-orbit operations consisted of 4.3 months of experiment setup, 11.6 months of science data collection, and 1.4 months of post-science calibrations. Analysis of the science data is now in progress.