Surface Water Ocean Topography (SWOT) satellite. Credit: Thales Alenia Space artist's concept

PARIS — The French space agency, CNES, on Sept. 29 contracted with Thales Alenia Space to build a next-generation radar altimeter for the billion-dollar U.S.-French SWOT, or Surface Water Ocean Topography, mission to launch in 2020.

Under the contract, valued at 5 million euros ($5.5 million) with an option for an additional 11 million euros, Thales Alenia Space will deliver SWOT’s Poseidon-3C nadir altimeter. The French-Italian company is already building the SWOT satellite platform under a CNES contract valued at 78 million euros that was signed in January.

The Canadian and British space agencies are also contributing to SWOT, which is a follow-on to the Topex-Poseidon and Jason satellites that the U.S. and French space agencies have built since the early 1990s. SWOT will extend the Jason ocean altimetry mission to rivers and lakes.

The Poseidon-3C instrument is the immediate successor to the Poseidon-3B radar altimeter mounted on the Jason-3 satellite, tentatively scheduled for launch in December aboard a SpaceX Falcon 9 v1.1 rocket from Vandenberg Air Force Base, California.

The launch date is pending SpaceX’s return to flight operations after the June failure of the Falcon v1.1, and the completion of a NASA investigation into the failure, which SpaceX has said must be finished before the agency will agree to proceed with the launch of Jason-3.

Peter B. de Selding was the Paris bureau chief for SpaceNews.