Jason-1 Satellite To Return To Service in Lower Orbit

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PARIS — The U.S.-French Jason-1 ocean-altimetry satellite, which was put into a safe-hold mode on March 3 after an on-board failure, is expected to return to service May 4 in a lower orbit, program managers said April 26.

The new orbit of 1,323.4 kilometers in altitude — some 12.6 kilometers lower than the former position — will permit ground controllers to operate Jason-1 until it fails completely, as this altitude is considered low enough to serve as a graveyard orbit, officials said.

The lower position means Jason-1 will not clutter the more-useful operational orbit in the event it fails without warning. It also reduces the number of years it will take before atmospheric drag pulls it into a destructive re-entry once it is retired.

Jason-1 was launched in December 2001 on what was supposed to be a three-year mission to succeed the larger U.S.-French Topex-Poseidon satellite.

Ocean altimetry’s popularity with civil and military customers has only grown since then.

Jason-2 was launched in August 2008, and has been operated in tandem with Jason-1 to increase the frequency of altimetry data returned to users. Jason-3 is scheduled for launch in 2014, and a successor satellite is being designed by the 19-nation European Space Agency.

The U.S.-French Jason operating team said Jason-1, whose instruments were switched on starting April 24 after a seven-week outage, should be able to perform partial service for at least another year.

“The move from the altimetry reference orbit has been a difficult decision to take, but it also signals the start of an exciting new chapter in the extraordinary mission of Jason-1,” the Jason-1 team from the NASA Jet Propulsion Laboratory and the French space agency, CNES, said in an April 23 message to users.