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Space

Jason-1 celebrates 4th year in orbit

07 December 2005

Initially designed for a service life of three years, Jason-1, the French-American ocean observation satellite, today celebrated its fourth year of operation in orbit. Jason-1 was launched on December 7, 2001. It was the first satellite to be built on Proteus, a platform purpose-designed by Alcatel Alenia Space in partnership with French space agency CNES for small satellites in low Earth orbit.

The main instrument on Jason-1 is the Poseidon-2 altimeter. It is the sole payload for this mission, a decision made by program partners based on the success of the experimental Poseidon-1 altimeter on the American satellite Topex (which had a U.S.-built operational altimeter). Alcatel Alenia Space was already prime contractor for the original instrument. After four years of in-orbit service, both operators and scientists have confirmed the Poseidon-2's exceptionally high mission availability and the excellence of its measurements.

This very-high-precision scientific instrument is being used in conjunction with CNES's high-precision orbit determination system, Doris, to improve the accuracy of ocean level measurements to within a centimeter. The satellite operates from an altitude of 1,350 kilometers.

The uninterrupted stream of data started in 1992 with Poseidon-1 and is continuing today. With more than 13 years of data under their belts, scientists have the depth and breadth of information needed to confirm even their most refined hypotheses and track phenomena that were previously out of their reach.

For the last four 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.

Using spaceborne altimetric measurements such as those from Jason-1 (the baseline mission), the Mercator forecasting model developed jointly by six French agencies (CNES, CNRS, SHOM, Météo France, Ifremer and IRD) supplies weekly oceanic forecasts covering the next two weeks. These forecasts are at ocean scale, using a 6-kilometer mesh, and will soon be at global scale, with a 20-km mesh at the equator. Forecasts cover about 40 different parameters, including currents and temperatures along an entire column of water.

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.

About Alcatel Alenia Space
Alcatel Alenia Space, leader in satellite systems and at the forefront of orbit infrastructures, brings together the vast experience and know-how of Alcatel Space and Alenia Spazio to form a new leading force in European space technology. Alcatel Alenia Space represents a worldwide standard for space development that impacts everybody's future: from navigation to telecommunications, from meteorology to environmental monitoring, from defence to science and observation. An affiliate of Alcatel (67%) and Finmeccanica (33%), Alcatel Alenia Space generated an estimated turnover of 1.8 billion euros with around 7,200 people in 2004.



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