spacetoday.net: NASA mission confirms elements of general relativity

Posted: Thu, May 5, 2011, 6:30 AM ET (1030 GMT)
Gravity Probe B illustration (Stanford Univ.)

A NASA mission more than half a century in the making has confirmed two key predictions of Einstein's theory of general relativity, project officials said Wednesday. Gravity Probe-B (GP-B), launched in 2004 but first proposed in the late 1950s, was able to detect the warping of spacetime caused by a gravitational body, as well as frame dragging, the effect on space time by a spinning object. The spacecraft measured these effects with four ultra-precise gyroscopes as the spacecraft orbited the Earth, aimed at one particular star. The conclusions are not particularly surprising, since other experiments and spacecraft have also collected evidence in support of general relativity, but project scientists said the GP-B data is the most direct confirmation of general relativity to date, although not to the same degree of precision as originally expected.