Current missions

There are seven altimetry satellites currently in orbit:

• Two satellites Jason-2 and Jason-3 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 is located on the former orbit of Topex/Poseidon (before 2002), Jason-1 (before February 2009), and Jason-2 (before July 2017). Between July 2017 and July 2018, Jason-2 operated on a lower orbit (named LRO for Long Repeat Orbit) at 1309.5 km.  From July 2018, Jason-2 is operating on an interleaved long repeat orbit (i-LRO), for the second geodetic cycle, on a ground track in the middle of the grid defined by the first geodetic cycle. 
• One satellite, Saral,  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 is complentary to Jason-2 ground tracks. From July 2016, SARAL is on a drifting orbit  for a new phase of the mission named “SARAL-DP” for SARAL-Drifting Phase". 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-2A, 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)
• 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.