Gravity Probe B: Testing Einstein Space — A Marriage of Physics and Technology C. W. Francis Everitt, W. W. Hansen Experimental Physics Laboratory, Stanford University

The NASA-Stanford University Gravity Probe B (GP-B) mission was launched from Vandenberg Air Force Base on 20 April, 2004. It will perform two highly accurate tests of two effects in General Relativity, Einstein's theory of gravitation, by means of orbiting gyroscopes: 1) the 6.6 arc-s/year geodetic effect due to the motion of the gyroscope through the curved space-time around the Earth; 2) the 0.042 arc-s/year frame-dragging effect due to the 'dragging around' of space and time by the rotating Earth. After an extensive initial set-up and calibration, GP-B entered the Science Data Collection Phase on August 27, with all parts of the instruments operating successfully. In addition to describing the GP-B science and the many new technologies developed for the experiment, an account will be given of the real-life experience of setting up and operating a scientific mission in space.