OPTIS satellite mission for improved tests of special and general relativity—Concept for a technology reference mission

Science goals: The mission OPTIS aims at testing the foundations of special and general relativity by up to three orders of improvement. The individual tests are
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• the isotropy,
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• constancy of the speed of light,
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• the time dilation (or Doppler effect),
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• the universality of the gravitational red shift with various combinations of high precision clocks.Furthermore, laser tracking allows
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• a much improved test of the Lense–Thirring effect,
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• of the perigee advance, and
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• a search for deviations from Newtonian gravity.Preconditions: Basic for the performance of this mission is the availablility of those technologies which have been used recently to carry through the most precise tests of special relativity. The precision of these tests can be further increased under space conditions thanks to longer integration times, larger changes in the orbital velocity and larger differences of the gravitational potential. Furthermore, very precise laser tracking and linking of satellites is a well-established technique and will provide, in combination with the active drag-free control system, very accurate orbit data.The technologies: The core technologies for OPTIS are
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• optical cavities,
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• highly stabilized lasers,
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• capacitive gravitational reference sensors,
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• drag-free control,
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• ion clocks,
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• frequency combs, and
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• laser tracking systems.These technologies are also key technologies for other future missions.