By Peter Weiss
On April 20, a satellite conceived in the 1960s to test two aspects of Einstein’s general theory of relativity finally roared into space from Vandenberg Air Force Base in California. Aside from two problems that have been solved—a backup thruster stuck open and a temporary computer malfunction due to radiation—all subsystems of NASA’s Gravity Probe-B (GP-B) are functioning as planned, the satellite’s handlers say.
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The mission had been canceled and reinstated seven times over a period of years. When the spacecraft reached its orbit and deployed all its solar panels, it “was a moment of considerable relief,” says physicist C.W. Francis Everitt of Stanford University, longtime head of the project.