Orbiting gyro test of general relativity

Over twenty years have elapsed since Leonard Schiff at Stanford and, independently, George E. Pugh at the Defense Department predicted that a gyroscope in orbit about Earth would precess as a consequence of Einstein’s general theory of relativity. Such behavior depends on an aspect of the theory of gravity that remains untested to this day. Although the concept is simple, the experiment is formidable: The precession is about 44 milliarcsec/year, to be measured with an accuracy of 1 milliarc‐sec per year. Undaunted, Schiff, together with Stanford colleagues William Fairbank and Robert Cannon, respectively, set up a program to develop the experiment. Since 1962, a Stanford team led by Francis Everitt and later having the support of NASA’s Marshall Space Flight Center, has patiently and persistently toppled many technical barriers, bringing the experiment from the realm of the improbable into the world of the possible. In late 1980, a committee of 16 scientists and engineers convened by NASA spent five days reviewing the technical readiness of the experiment, which is called the Gravity Probe B. They gave it a sound endorsement and concluded it was now ready to proceed to its flight phase.

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