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Satellite to test Einstein theory source: BBC | Apr 03, 04 | submitted by Rik Logtenberg

Palo Alto, CA - A satellite that will put Albert Einstein's Theory of Relativity to the test is ready to be launched. Nasa hopes Gravity Probe B will lift off from California on 17 April. Since it was first proposed in 1959, the project has been aborted and delayed because of technical hiccups many times.

Now it is ready to test two of Einstein's theories about the nature of space and time, and how the Earth distorts them.

The unmanned satellite will orbit 640km (400 miles) above Earth, measuring any slight changes in gravity.

Perfect spheres

The satellite will carry four ping-pong-sized balls made from quartz and sealed in a vacuum.


Gravity Probe B has been planned for 45 years (picture Nasa)
The scientists behind the project say they are the most perfect spheres ever made.

To ensure accuracy, the balls must be kept chilled to near absolute zero, inside the largest vacuum flask ever flown in space, and isolated from any disturbances in the quietest environment ever produced, said Anne Kinney, director Nasa's division of astronomy and physics.

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