Gravity Probe B
Launched on April 20, 2004, Gravity Probe B (GP-B) was a collaboration between Stanford University and NASA designed to test two previously untested aspects of Albert Einstein’s general theory of relativity (geodetic and frame-dragging effects) by observing the precession of four near perfectly spherical gyroscopes in reference to a distant star as the spacecraft travelled in a polar orbit 400 miles above the Earth.
Type
Orbiter
Launch
April 20, 2004
Location
Earth orbit
Objective
Measure two key predictions of Einstein's general theory of relativity
