Cooperative Space Venture to Study Ocean Topography

EARLY in August, a rocket will lift off from Kouru in French Guiana carrying a Franco-American satellite whose instruments will measure the topography of Earth's last frontier - the oceans - and help in the quest to understand global climate change.

Called Topex/Poseidon, the ambitious project is an example of two important trends in space science: increased international cooperation and a growing emphasis on Earth observation.

"Topex/Poseidon is one of the best examples right now of [these] two growing interests in the space field," says Hubert Curien, France's Minister for Technology and Space.

"The project brings together two national research efforts in a way that is beneficial to both, that is coming together faster than the two would have separately, that cuts out duplicate efforts, and which thus exemplifies the benefits of international cooperation," he says. "It is also a project that responds to growing public interest in efforts to better understand our own planet."

Using a battery of sophisticated instruments, Topex/Poseidon will measure sea-surface height with unprecedented precision (within about two centimeters or less than an inch). The resulting information will allow scientists to draw detailed maps of ocean-surface topography that in turn will afford new understanding of the speed and direction of ocean currents.

"Over the long term the goal is to study this information in conjunction with atmospheric circulation," says Michel Dorrer, Topex/Poseidon project director for France's National Center for Space Studies (CNES) in Toulouse.

"With a better knowledge of the quantity of carbon gases stored in the ocean and other such information, we can better understand the evolution in climate."

Topex/Poseidon - a conjunction of the American and French names for the satellite - will carry six instruments, four for the National Aeronautics and Space Administration and two for CNES. Data from NASA's instruments will be processed by the Jet Propulsion Laboratory in Pasadena, Calif., while data from the French instruments will be processed in Toulouse.

The data will be used in investigative projects set up by 38 teams of 200 scientists from a dozen countries.

"This is truly an international effort, and the first time there is such close Franco-American cooperation on this kind of project," says Mr. Dorrer. "We already have other ideas in mind for projects like this one that might never be undertaken by just one country."