Galileo Rubidium Standard - Lifetime data and GIOVE-A related telemetries

Galileo navigation program is in progress under the technical supervision of the European Space Agency (ESA). The preliminary activities related to GSTB-V2 experimental satellites provide the first results and the implementation of the In Orbit Validation (IOV) phase are in progress. Atomic clocks represent critical equipment for the satellite navigation system and clocks development has been continuously supported by ESA. The Rubidium Atomic Frequency Standard (RAFS) and the Passive Hydrogen Maser (PHM) are at present the baseline clock technologies for the Galileo navigation payload. For the RAFS, initial ground technological project related to lifetime possible limitation of the clock was already initiated in 2001. Telemetries of the operating RAFS on board of GIOVE-A provide highly valuable data to compare with the ground data and validate the selected method of 2001. This article gives an overview on the ground lifetime data of the RAFS in comparison with GIOVE-A data. Extrapolation for the 12 years Galileo mission duration is also provided.