US, French Scientists Plan to Map Ocean from Satellite
Robert C. Cowen, writer of The Christian Science Monitor, The Christian Science Monitor
THE new year brings a unique challenge to an international team of scientists who want to learn more about a poorly known climate factor - ocean circulation. They are preparing to make the first comprehensive survey of the topography of the ocean surface using a radar mapping satellite.
The year also presents a new challenge to the United States National Aeronautics and Space Administration. This will be the first NASA spacecraft to ride on a foreign rocket.
The Topex/Poseidon ocean topography experiment is a joint French/US mission. NASA is supplying the satellite and some of its instruments and paying about two-thirds of the mission cost. France's space agency, the Centre National d'Etudes Spatiales (CNES) is providing other instruments and, most important, an Ariane 42P rocket ready for launch in July from the Kourou space center in French Guiana.
For project scientist Lee-Lueng Fu at the California Institute of Technology's Jet Propulsion Laboratory in Pasadena, which manages Topex for NASA, this demanding mission breaks new professional ground in personal relations as well as scientific technique.
Asked if he had any reservations about launching the satellite on a foreign rocket, he said "certainly." But he quickly added that he has found the cooperation with French colleagues "very rewarding." He finds a greater challenge in mapping the sea.
Topex scientists hope to substantially increase understanding of ocean circulation. They cannot track sea currents directly. But sea-surface topography - the hills and valleys and broad slopes represented by small changes in sea level around the world - reflects the currents' flow.
To gain the desired knowledge, 38 investigator groups of Topex scientists in nine nations must turn their radar data into maps that show differences in sea level that are accurate to within a few centimeters over distances of hundreds or even thousands of kilometers. …