Current missions
There are ten altimetry satellites currently in orbit:
- Two satellites Jason-3 and JasonCS-Sentinel-6A Michael Freilich with a relatively short repeat cycle (10 days), able to observe the same spot on the ocean frequently but with relatively widely-spaced ground tracks (315 kilometres at the equator). Jason-3 and JasonCS-Sentinel-6A Michael Freilich are located on the former orbit of Topex/Poseidon (before 2002), Jason-1 (before February 2009), and Jason-2 (before July 2017).
- One satellite, Saral, on a drifting orbit since July 2016 for a new phase of the mission named “SARAL-DP” for SARAL-Drifting Phase". Before July 2016, it was on a 35-day repeat cycle, on the same ground-track as ERS-1&2 and Envisat (during its repetitive orbit, before 2010/10); it was complentary to Jason-3 ground tracks. The repetitive ground track is no more maintained and with the natural decay of the orbit, the ground track is drifting.
- One satellite - Cryosat-2 - with an altimeter (Siral) ables to work with an interferometric mode, with a high orbit inclination of 92° to satisfy the scientific requirements for observing the poles and the ice sheets, and with an orbit non-sun-synchronous (commonly used for remote-sensing satellites).
- HY-2B with a 14-day orbit at 963 km, until March 2016, then on a geodetic orbit (2 km higher, 168-day cycle with 2315 orbits in the full cycle), and HY-2C, with a 10-day orbit at 957 km & HY-2D.
- Sentinel-3A and Sentinel-3B with ground tracks similar to those of ERS-1&2, Envisat and Saral but with a 27-day repetitive cycle.
- CFOSat with its SWIM instrument dedicated to wave measurements, with rotating beams with different angles
- Swot, with its wide-swath interferometric instrument (and a classical nadir one)