The Topex/Poseidon satellite was launched on 10 August 1992 with the objective of "observing and understanding the ocean circulation". A joint project between Nasa, the US space agency, and Cnes, the French space agency, it carries two radar altimeters and precise orbit determination systems, including the Doris system.

Topex/Poseidon is laying the foundation for long-term ocean monitoring from space. Every ten days, it supplies the world's ocean topography, or sea surface height, with unprecedented accuracy.

From the launching of Jason-1, in December 2001, the 2 satellites had one-day shift. On September 15, 2002 Topex/Poseidon assumed a new orbit midway between its original ground tracks. Then, the former Topex/Poseidon ground tracks were overflown by Jason-1 and are currently overflown by Jason-2. These tandem missions demonstrate the scientific capabilities of a constellation of optimized altimetric satellites.
The mission ended on October 2005 due to a failure in a  pitch reaction wheel.

The Topex/Poseidon mission : an unrivalled success

Everybody, and in particular anyone who has been involved from the very beginning, is now left with the feeling that they were part of a great adventure, from a technical and above all a human perspective. During its thirteen years of operation, Topex/Poseidon witnessed many developments and innovations and even some media success. As for its overall success, the mission will be remembered both for the expected applications and the additional ones which led to greater interest in this type of satellite data.

Satellite  Topex/Poseidon
Launch on  10/08/1992
End Date  18/01/2006
Altitude  1336 km
Inclination  66 °
Repetitivity  9.9156 days
Agency  Nasa/Cnes
Goals  Measure sea surface height

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