Recherche

The Jason-2 spatial oceanographic satellite is designed to monitor oceans and climate. Based on high-precision oceanographic altimetry, it will introduce new data processing services supplied by Eumetsat, such as sea forecasts for ships, and coupling of this data with weather forecasts. The extraordinary harvest of data from the Topex/Poseidon mission has clearly proven the value of space altimetry in getting a closer, more accurate look at our oceans and better understanding our climate. The mission obviously had to be continued to carry on these vital measurements. The follow-on Jason-1/Poseidon-2 mission was therefore launched, and the Jason-2/Poseidon-3 program has been approved to ensure data continuity with Jason-1. Jason-2 is a quadrilateral program between CNES, NASA, NOAA and Eumetsat.

Mission
Over 71 % of the Earth's surface is covered by oceans which transfer heat and exchange matter with the atmosphere, helping to regulate our planet's climate. Space altimetry is one of the appropriate tool to observe changes in oceans and understand climate change. Furthermore, there are a number of people who are « users » of oceans, and for them it is important to know about changes in currents, whirlpools, wave height and over vital data. There are many important reasons to observe the oceans, from forecasting the weather and helping ships navigate, to ensuring better resources management and safer offshore construction. Space altimetry is unrivaled in all of these areas.  For the last five years, Jason-1 has passed over the same points on Earth every ten days to track the slightest changes in wind speed, wave height and average sea level. By observing these changes, meteorologists and climatologists can better analyze the impact of global warming, and better understand the origin of events such as El Nino, as well as the ocean's ability to absorb the resulting excess energy, heat and gases.

Role of Thales Alenia Space
Thales Alenia Space has provided the Proteus platform, developed in conjunction with CNES, has supplyed the Poseidon 3 altimeter for this mission, and is responsible of the assembly integration and tests of the complete satellite. Thales Alenia Space has already built Jason-1 and provided Poseidon 1 and Poseidon 2 altimeters.

Deeper in the program
Jason-2 will be placed into the same orbit at Jason-1, at an altitude of 1,336 kilometers, inclined 66 degrees, to provide virtually complete coverage of ice-free oceans. It will weigh about 600 kilos at launch, and have 550 watts of power.

The Poseidon-3 bi-frequency altimeter is still the main instrument of the mission, with measurement precision identical to its predecessor. However, Poseidon 3 also features an experimental mode that will support measurements closer to coastal zones, as well as on lakes and rivers. The instrument's RF unit is recurrent from Poseidon-2, while the digital unit largely reuses electronics from the SIRAL radar altimeter on the CryoSat mission.

Planning
Jason 2 is scheduled for launch in August 2008 from Vandenberg Air Force Base in California on-board a Delta II rocket.