Galileo program is approved by the European Commission and the European Space Agency (ESA). The activities related to GSTBV2 experimental satellite as well as the implementation of the in orbit validation 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. This article gives a general overview on the RAFS and the PHM developments and evolution up to now. It also provides updated information on the performance measurement results and qualification status

Galileo program is now approved by the European concerned government. The activities related to GSTBV2 experimental satellite as well as the implementation of the In Orbit validation phase have been started. Atomic clocks represent critical equipment for the satellite navigation system and clocks development has been continuously supported by ESA. The first related ESA contract for a RAFS (rubidium atomic frequency standard) was first initiated in 1996. RAFS is today one of the baseline clock technology for the Galileo navigation payload. This presentation gives a general overview of the RAFS development and evolution so far. It also provides updated information on the measurement results regarding clock frequency stability under simulated space environment as: i) vacuum coupled with temperature variation ii) electromagnetic perturbation iii) radiation variation (orbit cycle simulation) and total cumulated dose. Furthermore, measurement related to the capability of the clock to survive the vibration environment during launch without damage is addressed.