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Primary Mission Achieved: Jason launch 3rd anniversary, December 7, 2004
| This month the Jason mission satellite completes its primary three-year mission to measure the surface
height of the worlds' oceans. Launched in December 2001, Jason now begins an extended mission to continue
collecting detailed sea-surface topography data.
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Jason is the successful follow-on to the pioneering TOPEX/POSEIDON mission, which revolutionized our understanding
of the dynamics of ocean circulation and global climate. The sea-surface height measurements begun by
TOPEX/POSEIDON in 1992 and now carried on by Jason provide an unprecedented 13-year-long record of consistent,
continuous global observations of Earth's oceans. An early calibration phase of the mission allowed
TOPEX/POSEIDON and Jason to fly over identical ground tracks. For the first time, two radar systems fly
simultaneously over the same location, providing a unique opportunity to cross calibrate the spacecraft
instruments to remove systematic errors. The resulting data stream provides seamless coverage between the
two missions. This coverage allows scientists to observe and study both short-lived events such as hurricanes
and long-term climate phenomena such as the Pacific Decadal Oscillation. It also provides the capability to
monitor global mean sea level, an indicator of global temperature change. This calibration experiment provides
the first demonstration of how overlapping missions enable a long-term consistent data record.
Jason and its predecessor, TOPEX/POSEIDON, now fly in tandem, collecting even more detailed information
about Earth's oceans. "This novel satellite configuration with two simultaneous parallel measurements of
sea height provides a unique opportunity for scientists and operational users to move beyond global-scale
climate studies to small-scale ocean currents and their "practical uses" in marine transportation, safety,
and weather forecasting," says Dr. Lee-Lueng Fu, Jason and TOPEX/POSEIDON project scientist.
A follow-on mission to Jason, called the Ocean Surface Topography Mission (OSTM), is in development to
continue the legacy begun by TOPEX/POSEIDON. "The extended mission of Jason is expected to last to overlap
with OSTM in 2008 and to provide a cross-calibration opportunity similar to the one with TOPEX/POSEIDON,"
says Dr. Fu.
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