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The concept of using a spaceborne radar altimeter to measure ocean topography was formulated in the late 1960s. The concept was first demonstrated by Seasat (1978), followed by the U.S. Navy's Geosat (1985-89).

In 1979, NASA and JPL began planning TOPEX, an experiment that would use a satellite altimeter to measure the height of the world's oceans. At the same time CNES was designing an oceanographic mission called Poseidon. In the early 1980s, they pooled their resources to form the Joint US/ France TOPEX/Poseidon Mission (1992-present).

NASA provided the satellite bus and five instruments with their associated ground elements. JPL is responsible for project management, and operates the satellite through NASA's Tracking and Data Relay Satellite System. CNES furnished two instruments with their associated ground elements and a dedicated launch on a Ariane 42P rocket. Both CNES and NASA provide precision orbit determination and process and distribute data to 38 science investigators from nine nations, as well as other interested scientists.

In August 1992, TOPEX/Poseidon was launched from the European Space Agency's Space Center located in Kourou, French Guiana. From its orbit 1,336 kilometers (830 miles) above the Earth's surface, TOPEX/Poseidon measures sea level along the same path every 10 days using the dual-frequency radar altimeter developed by NASA and the CNES single-frequency solid-state radar altimeter.

Processing TOPEX/Poseidon data involves ground-based verification of the satellite measurements, an elaborate telecommunications system for commanding the satellite and receiving the data from its instruments, and a complex data-processing effort involving two NASA centers and the French space agency CNES.

Nothing succeeds like success. After 9 years of unprecedented success, TOPEX/Poseidon will be joined by Jason-1, the first of a series of advanced follow-on missions.