ThalesAlenia Space of France has delivered two satellite altimeters, called Sadko, to satellite prime contractor ISS Reshetnev of Russia for integration onto Russia’s Geo-IK-2 satellites to study Earth’s gravity field and tidal phenomena, according to ISS Reshetnev and European industry officials.

ThalesAlenia Space builds ocean-topography altimeters for the U.S.-European Jason satellite series and is under contract to provide similar gear for Europe’s Sentinel 3 satellite. These payloads will form part of a growing constellation of ocean surface-topography missions to include the Saral/Altika satellite from France and India, China’s HY-2A and HY-2B satellites, Europe’s Cryosat-2 and the U.S. Geosat Follow-on-2 spacecraft.

The United States and France are working on a SWOT, or surface water ocean topography, satellite with a tentative launch date of 2016. European governments hope to continue the Jason series with a mission called Jason-CS using a satellite platform derived from Europe’s Cryosat program.