Notes

• NOTE GNC versus AOCS: the term AOCS is commonly used when the orbit guidance is not performed on board, which is the case for standard LEO, MEO and GEO missions. GNC is commonly used for the on-board segment, when the satellite position is controlled in closed loop, for instance in case of rendezvous and formation flying. The GNC term can be also used for the whole function, distributed between on-board and ground systems.