Science Goals of the Primary Atomic Reference Clock in Space (PARCS) Experiment

摘要

The PARCS (Primary Atomic Reference Clock in Space) experiment will use a laser-cooled Cesium atomic clock operating in the microgravity environment aboard the International Space Station (ISS) to provide both advanced tests of gravitational theory and to demonstrate a new cold-atom clock technology for space. PARCS is a joint project of the National Institute of Standards and Technology (NIST), NASA's Jet Propulsion Laboratory (JPL), and the University of Colorado (CU). This paper concentrates on the scientific goals of the PARCS mission. The microgravity space environment allows laser-cooled Cs atoms to have Ramsey times in excess of those feasible on Earth, resulting in improved clock performance. Clock stabilities of 5×10{sup}(-14) at one second, and accuracies better than 10×10{sup}(-16) are projected. The relativistic frequency shift should be measureable at least 35 times better than the previous best, Gravity Probe A.[1] PARCS is scheduled for launch in 2007 and will probably y with the Stanford Superconducting Microwave Oscillator (SUMO), which will allow a Kennedy-Thorndike type experiment with an improvement of about three orders of magnitude compared to previous best results. PARCS will also provide a much-improved realization of the second, and a stable time reference in space. Significant improvements in testing fundamental assumptions of relativity theory, and in testing non-metric theories of gravity, are expected.