The European Space Agency (ESA) has lost contact with Envisat, its flagship Earth-observing satellite.
ESA mission control is working to re-establish contact with the satellite, which has stopped sending data after 10 years of service and 50,000 orbits of the Earth.
Envisat's given sterling service already, having been in orbit twice as long as it was designed for - but ESA's been hoping to keep it going until the launch of the first Sentinel missions next year.
"The interruption of the Envisat service shows that the launch of the GMES Sentinel satellites, which are planned to replace Envisat, becomes urgent," says Volker Liebig, ESA’s director of Earth observation programmes.
Scientists discovered that Envisat was lo longer transmitting when it passed over the Kiruna ground station in Sweden on April 8. Since then, a recovery team has been trying to re-establinh contact, but without success.
The satellite is still in a stable orbit around Earth.
Envisat is the world’s most complex Earth observation satellite, carrying 10 sophisticated instruments that have provided key information about our land, oceans, ice and atmosphere, including climate change.
Unless the team can bring it back online, ESA will now have to take advantage of an agreement with the Canadian Space Agency to use its Radarsat satellite to fulfil its obligations until the Sentinel missions start to launch next year.