Satellite Used to Study Effects of General Relativity

The Tartan Online, Carnegie-Mellon’s student newspaper, chooses Gravity Probe B as its "Experiment of the Week":

Gravity Probe B, a well-endowed NASA/Stanford satellite, is at this moment orbiting the Earth. The satellite’s main feature is its four perfectly spherical, shiny balls. These balls serve as the world’s most perfect gyroscopes, used in an extraordinarily complex and expensive experiment to observe the effects of general relativity…. Einstein’s theory predicts that a rotating massive body should slowly “frame-drag” space and time around with it. Over time, this dragging effect should push the gyroscope’s axis of rotation about 40 milliarc-seconds out of alignment. That’s the width of a human hair as seen from 10 miles. The probe intends to measure this to an accuracy of one percent.

Stanford University, which is working with NASA on the mission, has a mission status webpage that is worth checking out. Also be sure to check out the vehicle tour and the image gallery, featuring schematics of the satellite and pictures of the launch. What other satellite mission websites have you found? Post a link in the comment, or post your own blog entry, and we may promote your link to the homepage.