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'Einstein' probe set for launch

A satellite that will put Albert Einstein's Theory of Relativity to the test is due for lift off at 1801 GMT.

The US space agency's $700m (£387m) probe will launch on a Boeing Delta 2 rocket from Vandenberg Air Base in California.

Gravity Probe B will test Einstein's ideas about space and time and how the Earth distorts them.

It will carry four near-perfect spheres in gyroscopes to help verify two key elements of Einstein's theory.

The probe will align itself with a "guide star" IM Pegasi so that their spin axes point to this star. Over the course of the year the spin axes will be monitored for tiny changes that could be caused by the effects Einstein described.

See how the probe will work

Once in space, the unmanned satellite will orbit 640km (400 miles) above Earth.

Spinning around

Einstein argued that the space-time continuum was twisted and distorted by the spinning of massive objects, an effect known as "frame dragging".

"We've seen two of the three aspects of warped space-time. We've seen the warping of space and the warping of time. We have never seen, in any clean way, the dragging of space into motion," said Kip Thorne of the California Institute of Technology.

These effects have important implications for the nature of matter and the structure of the Universe.

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.

The idea of the mission was first proposed in 1959, but the project has been aborted and delayed many times due to budget reviews.

Posted by thinkum at April 19, 2004 12:45 PM