Joint U.S./French Topex/Poseidon Satellite

In 1979, NASA's Jet Propulsion Laboratory began planning TOPEX, an Ocean Topography Experiment that would use a satellite altimeter to measure the surface of the world's oceans. At the same time the French space agency Centre National d'Etudes Spatiales (CNES) was designing an oceanographic mission called Poseidon, named for the Greek god of the Sea.

Launch

During August 1992, TOPEX/Poseidon was launched into Earth's orbit by an Ariane 42P rocket from the European Space Agency's Space Center located in Kourou, French Guiana -- the first launch of a NASA payload from this site. 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 altimeter developed by NASA and the CNES single frequency solid-state altimeter. This information is used to relate changes in ocean currents with atmospheric and climate patterns.

The two space agencies decided on a cooperative effort and pooled their resources to form a single mission. The result is the highly-successful TOPEX/Poseidon which has achieved science objectives beyond expectations and at a lower cost that either mission would have achieved separately. The satellite has continously surveyed the oceans' surface currents with radar altimeters since launch in 1992. The satellite orbits Earth 4 700 times per year, and engineers are optimistic that the missoin will continu to collect data through at least Septemeber 1998.

The actual working team fot the TOPEX/Poseidon Satellite

Building on three earlier earth-orbiting missions TOPEX/Poseidon - a joint mission between the US and France - is part of a global oceanographic effort to acquire a comprehensive look at the world's oceans. TOPEX/Poseidon's contribution involves continuous observations of the surface currents of the ocean.

TOPEX/Poseidon is based on earlier earth-orbiting satellite missions. The earliest missions provided proof of the concept that some ocean observations can be made more economically and with better coverage from space than from the earth's surface. Each mission carried a different complement of instruments and discovered new facts that inspired successive missions and generations of spacecraft.

Actual Image from the TOPEX/POSEIDON satellite.

The International Science Working Team for the data of the TOPEX/Poseidon

Data from TOPEX/Poseidon are analyzed and interpreted by the International Science Working Team. This team is composed of 38 groups of scientists from Australia, France, Germany, Japan, the Netherlands, New Caledonia, Norway, South Africa, the United Kingdom, and the United States.