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TOPEX/Poseidon mission graphic

Phase: Past

Launch Date: August 10, 1992

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TOPEX/Poseidon monitored global ocean circulation, improved global climate predictions, and tracked El Niño conditions and ocean eddies. After over 62,000 orbits, the satellite has ceased operations. TOPEX/Poseidon remains in orbit 830 miles above the Earth, posing no threat to the planet.

The mission's most important achievement was to determine the patterns of ocean circulation - how heat stored in the ocean moves from one place to another. Another of the mission's major accomplishments was to develop the most accurate ever global ocean tide models.

Furthermore, TOPEX/Poseidon was the first mission to demonstrate that the Global Positioning System could be used to determine a spacecraft's exact location and track it in orbit. Knowing the satellite's precise position to within 2 centimeters (less than 1 inch) in altitude was a key component in making accurate ocean height measurements possible.

TOPEX/Poseidon used the global perspective available only from space to develop maps of ocean topography showing the barely perceptible hills and valleys of the sea surface. This effort significantly expanded the knowledge developed from shipboard research, which is limited to specific locations. From TOPEX/Poseidon data, scientists calculated speed and direction of ocean currents worldwide to better understand how the oceans transport heat from the Earth's equatorial region toward the poles, thus regulating global climate.

Jason, a follow-on oceanography mission launched in December 2001, is continuing TOPEX/Poseidon's study of ocean circulation and its effects on the Earth's climate. Jason precisely maps the surface height, wind speed and wave height of 95 percent of Earth's ice-free oceans every 10 days. The data provide invaluable input for short-term weather forecasting, long-term climate forecasting and prediction models. In the few years that Jason and TOPEX/Poseidon operated in tandem, they provided twice the coverage of the sea surface and allowed scientists to study smaller features than could be seen by one satellite.