Satellite launch accident provides unexpected test of Einstein’s theory

A pair of stranded satellites will perform a test of Albert Einstein's general theory of relativity that they were not designed to do. The results will be more precise than previous tests

It's a total fluke. No one was thinking about making the most precise test yet of general relativity when the Soyuz rocket lifted off from French Guiana on 22 August 2014. The European Space Agency was launching Galileo 5 and 6, a pair of navigation satellites to break Europe's reliance on the American GPS system.

At first everything appeared to be going well. The rocket cleared the launch pad and sped away from the surrounding rain forest on its way to space. But trouble was brewing inside the rocket's upper stage, the final motor that would put the satellites into their operational orbit.