Jason 2, 3 (OSTM)

Jason 2 (OSTM) [NASA]

The Jason 2 or OSTM (Ocean Surface Topography Mission) is a follow-on to the Jason-1 mission.

Jason-2 is a quadripartite program organized by CNES, NASA, NOAA and Eumetsat. Based on high-precision oceanographic altimetry, it introduced new data processing services supplied by Eumetsat, such as sea forecasts for ships, and coupling of this data with weather forecasts.

The 40-million euro CNES contract covers manufacture of the Poseidon-3 altimeter, the primary instrument for the mission, plus a payload module to manage all the instruments, and the assembly, integration and testing of the satellite. The Proteus platform used for the satellite is covered by a contract for five platforms that Alcatel Space has already received from CNES.

Following instruments are onboard:

• CNES Poseidon-3 Altimeter (C- and Ku-band) measures height above sea surface
• NASA Advanced Microwave Radiometer (AMR) Three-frequency radiometer measures total water vapor along altimeter path to correct for pulse delay
• CNES Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) Doppler tracking antenna receives ground signals for precise orbit determination, satellite tracking, and ionospheric correction data for CNES altimeter
• NASA Global Positioning System Payload (NavstarP) receiver provides precise orbit ephemeris data
• NASA Laser Retroreflector Array (LRA) works with ground stations to track satellite and calibrate the other satellite location systems, and verify altimeter measurements.

Jason-2 carries on its predecessor's mission of monitoring and precisely measuring the oceans. In addition, Jason-2 incorporates the experimental Wide Swath Ocean Altimeter (WSOA), supplied by NASA, to enhance spatial coverage. The WSOA instrument enables measuring meso-scale phenomena such as vortices inside ocean currents to improve our ocean circulation models.

Jason-2 was placed into the same orbit at Jason-1, at an altitude of 1,336 km, inclined 66 degrees, to provide virtually complete coverage of ice-free oceans. It weights about 600 kg at launch, and have 550 W of power.

Thales Alenia Space announced to have signed with French Space Agency (CNES), the contract to build the follow on Jason-3 satellite.

The Jason-3 operational oceanographic mission involves a quadripartite collaboration between the two meteorological organizations Eumetsat and NOAA, acting as the leaders of the program, and CNES and its American counterpart NASA.

Jason-3 will allow the continuity of high precision ocean topography measurements beyond TOPEX/Poseidon, Jason-1 and Jason-2, which are now operational in orbit. It will also provide a bridge to an operational mission to enable the continuation of multi-decadal ocean topography measurements. Jason 3 will offer the same ocean measurement accuracy as Jason-2, including near coastal zones, as well as lakes and rivers. CNES has offered a spare Jason-2 platform, already built, for Jason-3.

Based on the Proteus platform, Jason-3 features the Poseidon-3B altimeter, also developed by Thales Alenia Space in Toulouse. The Poseidon-3B dual-frequency altimeter continues to be the key instrument in this spaceborne observation programme. Included in the core mission, Jason-3 will embark the DORIS precise orbit determination system, an Advanced Microwave Radiometer (AMR), a GPS payload (NavstarP), and a Laser Retro-reflector Array (LRA).

The satellite will be placed in the same orbit as Jason-2, at an altitude of 1,336 km with an inclination of 66 degrees, to provide virtually blanket coverage of all ice-free ocean surfaces. Its weight at launch is 553 kilogrammes, with 550 W of power and pointing accuracy of 0.15° (half-cone). Its launch is expect ed for mid 2013 for a mission life of 3 years.