Atomic Clock Ensemble in Space

Time and Frequency Transfer laboratory is planning to participate in the ACES (Atomic Clock Ensemble in Space) mission of the European Space Agency (ESA) ^{*1, *2}. ACES will perform fundamental physics tests such as precise measurements of the gravitational redshift. International space station (ISS) will carry two high-performance atomic clocks for that purpose. One of the ground terminals paired with ISS will be installed at NICT. Optical and microwave atomic clocks being developed in Tokyo area will contribute to the ACES mission through the ground terminal at NICT. The launch of ACES payload is scheduled in 2018.