Atomic Clock Ensemble in Space (ACES) Operations. The ISS External Scientific Payload Looking for Experimental Confirmations on the General Relativity Theory

摘要

ACES is an ESA mission in fundamental physics based on a new generation of clocks operated in the microgravity environment of the ISS. It is expected to reach in microgravity conditions a time drift of 1 ? 10~(-16) s/s, corresponding to a time error of about 1 s over 300 million years. This accurate time scale reference will be distributed on Earth via microwave and laser links, allowing ACES to perform tests on the Einstein's general relativity theory, including an accurate measurement of the gravitational red-shift, a search for time variations of fundamental constants and tests of the Standard Model Extension. ACES also develops applications in different areas of research including geodesy and Earth observation. ACES will be launched and installed on the nadir pointing ISS Columbus External Payload Facility in late 2018/ early 2019 and is foreseen to have an operational mission of 1.5 to 3 years. This paper gives an overview of the ACES system (on-board and on the ground), describes the different interfaces and operational baseline and gives the current status.