NASA Orbital Experiment To Test Einstein's Theory

When Gravity Probe B was first proposed by NASA, Dwight D. Eisenhower was president. Cuba was still considered a friendly country and Vietnam was a place few Americans could point to on a map. Manned space flight was still an unrealized dream.

Now, 45-years later, Gravity Probe B is finally being prepared for lift-off at Vandenberg AFB (CA). It's mission: test two linchpin theories first proposed by Albert Einstein. In 1916, Einstein figured a planet like Earth could actually mold and twist the fabric of space and time. Think of a lead weight resting in the middle of a soft mattress and you'll get an idea of what he had in mind. That very effect, he proposed, is directly responsible for gravity.

Since 1959, the probe has survived -- barely, in some cases -- cancellation, technical problems and launch delays. But April 17th, Gravity Probe B will finally launch.

The probe is built around four perfectly spherical balls, about the size of ping-pong balls. They're made of quartz and touted as the most perfect spheres ever created by man. They're packed in vacuum thermoses and cooled to near absolute zero.

Here's how Stanford University puts it: "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.

FMI: http://einstein.stanford.edu