Early results from a NASA mission designed to test two key predictions of Albert Einstein show the great man was right about at least one of them. It will take another eight months to determine whether he got the other correct, say scientists analysing data from NASA’s Gravity Probe B satellite. The spacecraft was launched into orbit from Vandenberg Air Force Base, California, on April 20, 2004. Gravity Probe B uses four ultra-precise gyroscopes to measure two effects of Einstein’s general relativity theory. One of these effects is called the geodetic effect, the other is called frame dragging. The mission’s principal investigator, Professor Francis Everitt from Stanford University, discussed preliminary results at the American Physical Society meeting in Jacksonville, Florida. The data from Gravity Probe B’s gyroscopes clearly confirm Einstein’s geodetic effect to a precision of better than 1%.
Stanford University – Gravity Probe B

NASA – Gravity Probe B: The Relativity Mission