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Meanwhile, a plan to seek Einstein's predicted gravitational waves, which are ripples in space itself, passed a major milestone June 18. In a ceremony at the Paris Air Show, the heads of National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) signed a formal agreement to proceed with the first stage of this joint project. For the project to succeed, physicists must be able to guarantee that a mass can float freely in space completely undisturbed by anything but gravitational waves. Engineers must also be able to control the spacecraft position to within a few millionths of a millimeter. The first step is to launch a satellite to test those skills in 2010.
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Position a spacecraft to within a few millionths of a millimtere? Come on - they can't even do that on the ground, let alone in space. And relative to WHAT?