To test Einstein's theory of general relativity, Gravity Probe B must measure two minuscule angles with spinning gyroscopes, floating in space.
While the concept of Gravity Probe B is relatively simple, carrying out the experiment required some of the most accurate and sophisticated technology ever developed.
Out of the dozens of new technologies that Stanford, NASA and Lockheed Martin had to invent, one was creating the most perfect sphere ever.
Every manufactured sphere has slight imperfections on its surface. However, for Gravity Probe B, they created a gyroscope-sphere so perfect that it didn’t deviate from its axis by more than one hundred-billionth degree per hour of spinning!