Probe measures swirling space, at last

摘要

SIX years after NASA's Gravity Probe B stopped collecting data, the mission has finally found evidence of an effect of general relativity called frame-dragging. But the result comes years after other projects measured the effect to greater precision. The $750 million mission launched in 2004 to test Einstein's general theory of relativity by measuring how Earth warps the fabric of space-time. The warping was expected to slightly alter the spin axis of four gyroscopes in the probe, but the measurements were much noisier than expected, complicating the analysis.