The TOPEX/Poseidon satellite was a joint venture of NASA and the French space agency, CNES. It measured ocean surface topography to an accuracy of 4.2 centimeters, unprecedented at the time, from its launch in 1992 to the end of its mission in 2006.

The satellite's achievements included highly accurate measurements of sea level, continuous monitoring of ocean topography, observation of the effects of currents on global climate change, and production of the first global views of seasonally changing currents.

TOPEX/Poseidon also monitored large-scale ocean features such as Rossby and Kelvin waves, and made important observations of the effects of regional global phenomena including El Niño, La Niña and the Pacific Decadal Oscillation.