Launch readiness of CHEOPS is planned for 2018. The baseline scenario is a shared launch as auxiliary payload or co-passenger in Vega, or Soyuz or in another small launch vehicle.
The baseline orbit is Sun-synchronous, with an altitude in the range between 650 and 800 km and a local time of the ascending node of 06:00. This choice permits the rear of the spacecraft to be permanently Sun-pointed, is optimal for uninterrupted observations, and keeps thermal variations of the spacecraft and Earth stray light on the satellite to a minimum as the orbital plane follows, as closely as possible, the day/night terminator.
Planning of the observations will be carried out at the Science Operations Centre (SOC) and communicated to the Mission Operations Centre (MOC), where spacecraft commanding sequences will be uplinked via ground station antennas. The spacecraft telemetry will be routed from the MOC to the SOC for calibration, processing and archiving.
The data budget for CHEOPS is estimated at 1.2 Gb/day. An S-band system is presently baselined for data downlink, telemetry and telecommanding. A duration of 3.5 years for science operations is baselined to enable the execution of the proposed core programme, with an allocation of 20% of the observing time open to the whole scientific community.
Execution of the low-Earth orbit phase (LEOP) and in-orbit commissioning will be performed by the spacecraft contractor, with an ESA-appointed flight director taking overall operation authority. Following the successful in-orbit commissioning of the spacecraft, responsibility for CHEOPS operations will be taken over by the CHEOPS Mission Consortium. The MOC will be under the responsibility of Spain, while the SOC and the coordination of the ground segment will be located at the University of Geneva (Switzerland).