The ACES GNSS Subsystem and its Potential for Radio-Occultation and Reflectometry from the International Space Station

The ESA mission Atomic Clock Ensemble in Space (ACES) will operate a new generation of ultra-stable and accurate atomic clocks on board the International Space Station in 2013-2015. The ACES payload will be attached externally to the European Columbus module. A commercial-of-the-shelf GNSS receiver will be connected to the ACES clock signal. Primarily, the receiver will ensure orbit determination of the ACES clocks in order to apply relativistic corrections to the space-to-ground comparison between the ACES clock signal and the ground clock. Secondarily, the receiver offers the potential for remote sensing from space in the field of radio-occultation and reflectometry exploring the use of the new GNSS signals. The paper presents the current status of the ACES GNSS instrument