Gravity Probe B

The launch of Gravity Probe B has been delayed. [This was originally posted on December 4](It was scheduled for launch on Saturday, December 6.)

UPDATE

The Gravity Probe B website says:

A new launch date, which is anticipated to be sometime in the 2nd Quarter of 2004, will be announced soon by NASA.

Stanford University's Gravity Probe B website describes the experiment:

Gravity Probe B is the relativity gyroscope experiment being developed by NASA and Stanford University to test two extraordinary, unverified predictions of Albert Einstein's general theory of relativity.

The experiment will check, very precisely, tiny changes in the direction of spin of four gyroscopes contained in an Earth satellite orbiting at 400-mile altitude directly over the poles. So free are the gyroscopes from disturbance that they will provide an almost perfect space-time reference system. They will measure how space and time are warped by the presence of the Earth, and, more profoundly, how the Earth's rotation drags space-time around with it. These effects, though small for the Earth, have far-reaching implications for the nature of matter and the structure of the Universe.

As Peter Weiss in the November 1, 2003 issue of Science News describes the thing Gravity Probe B is going to observe, "frame-dragging"--

Any spinning body in space, including Earth, ought to drag some space-time along with it. That was Einstein's prediction, anyway. The effect has never been convincingly observed.

This project has taken 40 years to get off the ground. Find out more at these links:

Read The Story of Gravity Probe B from Stanford (PDF, 115KB) for more about the project's purpose and history.

Stanford's Gravity B website

News about Gravity Probe B from NASA's Marshall Space Flight Center

I'm not including links to JPL's pages about Gravity Probe B . . .

since they haven't been updated for several years, apparently.

It's better to maintain pages or take them down.

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