The Ssalto multimission ground segment (Segment Sol multimissions d'ALTimétrie, d'Orbitographie et de localisation précise) encompasses ground support facilities for controlling the Doris and Poseidon instruments, for processing data from Doris and the Topex/Poseidon, Jason-1 and Envisat-1 altimeters, and for providing user services and expert altimetry support.

Ssalto was designed by Cnes, the French space agency, in partnership with its subsidiary CLS and local industry. Ssalto will serve as a common ground segment for the Doris/Spot, Doris/Envisat, Topex/Poseidon, Jason-1 and Envisat missions. It thus responds to a growing commonality of user needs and will support the continued operation of Doris instruments and altimetry payloads flying simultaneously on different satellites.

Ssalto encompasses the resources to:

• control onboard Doris and Poseidon instruments, and the Doris orbitography beacon network (CCI)
• obtain precision orbits (POD)
• process altimeter and radiometer data (CMA)
• provide user services, and archive and manage data (Aviso)