OSTM/Jason-2

OSTM/Jason-2, or Ocean Surface Topography Mission/Jason-2 satellite, was an international Earth observation satellite altimeter joint mission for sea surface height measurements between NASA and CNES. It was the third satellite in a series started in 1992 by the NASA/CNES TOPEX/Poseidon mission and continued by the NASA/CNES Jason-1 mission launched in 2001. Like its two predecessors, OSTM/Jason-2 used high-precision ocean altimetry to measure the distance between the satellite and the ocean surface to within a few centimeters. These very accurate observations of variations in sea surface height — also known as ocean topography — provide information about global sea level, the speed and direction of ocean currents, and heat stored in the ocean. Jason-2 was built by Thales Alenia Space using a Proteus platform, under a contract from CNES, as well as the main Jason-2 instrument, the Poseidon-3 altimeter (successor to the Poseidon and Poseidon 2 altimeter on-board TOPEX/Poseidon and Jason-1). Scientists consider the 15-plus-year climate data record that this mission extended to be critical to understanding how ocean circulation is linked to global climate change. OSTM/Jason-2 was launched on 20 June 2008, at 07:46 UTC, from Space Launch Complex 2W at Vandenberg Air Force Base in California, by a Delta II 7320 rocket. The spacecraft separated from the rocket 55 minutes later. It was placed in a circular, non-sun-synchronous orbit at an inclination of 66.0° to Earth's equator, allowing it to monitor 95% of Earth's ice-free ocean every 10 days. Jason-1 was moved to the opposite side of Earth from Jason-2 and now flies over the same region of the ocean that Jason-2 flew over five days earlier. Jason-1's ground tracks fall midway between those of Jason-2, which are about apart at the equator. This interleaved tandem mission provided twice the number of measurements of the ocean's surface, bringing smaller features such as ocean eddies into view.