CNES is in charge of developing and integrating the PHARAO clock, which is the main French contribution to ACES (Atomic Clock Ensemble in Space), an ESA project. In ACES, PHARAO is coupled to an active maser, the SHM, provided by Switzerland. Both clocks are complemented by the microwave link (MWL), a time-transfer device of unprecedented accuracy.
The French or international laboratories involved in PHARAO are:
- the Kastler-Brossel Laboratory (LKB) attached to the Ecole Normale Supérieure
- the LNE/SYRTE time and space reference systems laboratory
- the International Bureau of Weights and Measures (BIPM)
PHARAO/ACES is expected to foster broad international scientific cooperation by allowing any laboratory equipped with a MWL ground terminal to compare its time and frequency reference to PHARAO's.