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 completed 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 Laboratoire des Systèmes de Référence Temps et Espace (LNE/SYRTE)
- the BIPM (Bureau International des Poids et Mesures)
PHARAO/ACES is expected to trigger a wide international scientific cooperation by allowing any laboratory equipped with a MWL ground terminal to compare its time and frequency reference to PHARAO's.