PARIS — The European Space Agency (ESA) declared May 9 that its huge Envisat Earth observation satellite is definitively lost and that while teams will continue until July to try to revive it, the chances of resuscitation are “extremely low.”
Envisat stopped communicating April 8 and since then has been the subject of an international effort to determine the satellite’s status that included images from German ground radar and from the French Pleiades high-resolution optical Earth observation satellite that passed nearby.
Launched in 2002 on a five-year mission, Envisat is the largest nonmilitary satellite ever orbited. Its 10 observing instruments are deployed on a core satellite structure 8 meters in length.
With its antennas deployed in orbit, Envisat measures 26 meters by 10 meters by 5 meters and will now become one of the more dangerous pieces of space garbage.
From its current near-polar low Earth orbit at 783 kilometers in altitude, the satellite can be expected to continue circling the globe for at least 100 years, according to ESA forecasts. In its 10 years of operations, Envisat performed collision avoidance maneuvers on about a dozen occasions — maneuvers that have been impossible since the satellite stopped communicating.
The death of Envisat means ESA is now under more pressure to come to an agreement with the commission of the 27-nation European Union on financing for a broad environmental observation program called Global Monitoring for Environment and Security (GMES).
ESA and the commission had wanted the first GMES satellite, called Sentinel-1, to be launched in 2013 and to operate in tandem with Envisat for several months before Envisat’s planned retirement. That will no longer be possible, and users of Envisat data that will be furnished by Sentinel-1 will now have a gap in data flow, which they say is problematic.
Because the European Commission has refused to confirm its financing for operations of the Sentinel satellite series, ESA has threatened to keep Sentinel-1 on the ground. The two sides hope to resolve their differences in the coming months.
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