MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Contacts:  NASA Headquarters/David E. Steitz  (202) 358-1730
      JPL/Alan Buis  (818) 354-0474

FOR IMMEDIATE RELEASE                          Nov. 19, 2001

NASA/FRENCH OCEAN-OBSERVING SATELLITE SET TO SOAR

     The Dec. 7 launch of Jason 1, NASA's newest oceanography 
satellite, will continue the mission started by Topex/Poseidon 
to monitor global climate interactions between the sea and the 
atmosphere. 

     Jason 1 will monitor world ocean circulation, study 
interactions of the oceans and atmosphere, improve climate 
predictions, and observe events like El Nino. Jason 1 is a 
joint U.S./French oceanography mission.

     "Jason 1 will be a tremendous asset to our oceanography 
program. It will take the research and development activities 
done so successfully on Topex/Poseidon and add operational 
utility and function," said Dr. Ghassem Asrar, associate 
administrator for NASA's Earth Science Enterprise, NASA 
Headquarters, Washington.

     Since the oceans are so large, remote sensing from 
satellites has proved to be the only way to get global 
information about these vast, hard-to-measure expanses.  
Spaceborne altimeters, such as the Poseidon 2 instrument that 
Jason 1 carries, can calculate ocean heights to within 
centimeters.

     Gary Kunstmann, Jason 1 project manager at NASA's Jet 
Propulsion Laboratory, Pasadena, Calif., said, "We're very 
excited about this launch and looking forward to greater 
knowledge of the 'whys' and 'hows' of the world's climate 
systems." 

     Jason 1 is the follow-on to the very successful 
Topex/Poseidon satellite, a U.S.-French mission that has been 
making precise measurements of ocean-surface topography since 
1992. 

     The ocean and atmosphere transport heat from the 
equatorial regions toward the icy poles, and the atmosphere 
sends heat through a complex, worldwide pattern of winds. As 
these winds blow across the oceans, they help drive the 
currents and exchange heat, moisture and gases with the water. 
While winds create daily, short-term weather changes, the 
oceans have a slower, much longer-lasting effect on climate. 
The powerful forces of wind and water combine to help regulate 
the planet's climate. 

     Accurate observations of sea-surface height and ocean 
winds provide scientists with information about the speed and 
direction of ocean currents and the heat stored in the ocean, 
which in turn reveals global climate variations. Jason 1 will 
help scientists in their quest to understand these global 
climate forces.

     Weighing about 500 kilograms (about 1,100 pounds), Jason 
1 is only one-fifth the weight of Topex/Poseidon. After 
launch, Jason 1 will enter orbit about 10 to15 kilometers (6 
to 9 miles) below Topex/Poseidon's 1,337-kilometer-altitude 
(830-mile) orbit. During the next few weeks, Jason 1 will use 
its thrusters to raise itself into the same orbital altitude 
as Topex/Poseidon, and then move in close behind its 
predecessor, trailing by about 500 kilometers (300 miles). 

     The two spacecraft will fly in formation, making nearly 
simultaneous measurements. The science team will compare the 
data to make sure the instruments are calibrated exactly.  
This procedure is expected to take about six months. Jason 1 
will then assume Topex/Poseidon's former flight path, and the 
older satellite will move into a parallel ground track midway 
between two Jason 1 ground tracks. Jason 1's mission is 
designed to last three years. 

     Jason 1 carries five instruments:  the Poseidon 2 
altimeter, the spacecraft's main instrument, to measure 
altitude; a microwave radiometer to measure atmospheric water 
vapor; and three precision location-finding instruments.

     Jason 1 is a joint project between NASA and France's 
Centre National d'Etudes Spatiales. The U.S. portion of the 
mission is managed for NASA's Office of Earth Science, 
Washington, by JPL, a division of the California Institute of 
Technology in Pasadena.


     More information about the Jason 1 program is available 
at: http://sealevel.jpl.nasa.gov and on the JPL home page at 
http://jpl.nasa.gov .

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11/19/01  NL/AB
2001-224

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