* Astronomy

On its 528 mission day, the Gravity Probe B satellite finished collecting data.
The probe has been orbiting the Earth for more than 17 months. It used four ultra-precise spherical gyroscopes to generate data to test Albert Einstein’s general theory of relativity.

Now, Fifty weeks worth of data has been downloaded from the spacecraft and relayed to computers in the Mission Operations Centre at Stanford University, Stanford, California, US. where researchers will analyse and validate the data, which is expected to take approximately one year.
On the 30 September, 2005, the liquid helium required to keep the science instruments cool was depleted, thus ending the data gathering.

"This has been a tremendous mission for all of us. With all the data gathered, we are proceeding deliberately to ensure everything is checked and re-checked. NASA and Stanford can be proud of what has been achieved so far" - Francis Everitt, Gravity Probe B principal investigator at Stanford.

Launched on April 20, 2004, from the Vandenberg Air Force Base, US., Gravity Probe B has been precisely measuring two effects predicted by Einstein's theory. One is the geodetic effect, the amount by which the Earth warps the local space time in which it resides. The other, called frame-dragging, is the amount by which the rotating Earth drags local space time around with it.

"The completion of the GP-B mission is the culmination of years of hard work, training and preparation by the GP-B team" - Tony Lyons, NASA GP-B program manager from NASA’s Marshall Space Flight Centre in Huntsville, Alabama, US.

"We are proud to have been associated with this extremely significant mission. Working with Stanford and NASA, we formed a powerful team to develop the challenging technologies needed to take a giant step forward in helping understand Einstein's theory of general relativity" - Bob Schultz, Lockheed Martin's Gravity Probe B program manager.