April 13, 2012
ESA Still Trying To Communicate With Flagship Satellite
Radar pictures taken from the ground appear to show that the satellite is intact, but there is no confirmation that Envisat has entered the "safe mode" of an ailing spacecraft.
During this mode, the spacecraft ensures the solar panel is pointed at the Sun and that onboard power systems are prioritized above all other activity.
If the satellite has not entered "safe mode," the scientists are concerned that Envisat's batteries could soon become deplete.
"We continue to try to re-establish contact with the satellite, and in parallel to collect more information on the satellite's status by ground radar images, from optical images, from telescopes, but also from other spacecraft," Prof Volker Liebig, the director of Earth observation at ESA, told reporters.
"On Sunday, [the French space agency] will try to program [their new high-resolution imaging satellite] Pleiades to see if they can image Envisat, to give us more detailed knowledge on whether there is damage on the outside," he said.
Envisat was launched in 2002 and is the biggest non-military Earth observation satellite that has ever been placed into orbit.
Communication with the 8.8-ton spacecraft was lost over the weekend shortly after it downloaded pictures of Spain's Canary Islands.
The satellite was expected to be turned off in 2014 by ESA once the first of the Sentinel series of follow up spacecraft made their way to space.
Scientists had hoped to have both Envisat and the Sentinel series operating in orbit together for a period of time so they could cross-calibrate their data.
Sentinel 1, which was supposed to take over the radar duties for Envisat, is expected to be launched next year.
This satellite will be followed by Sentinels 2 and 3, which will image changes on the land and over the oceans in early 2014.
Envisat has orbited the Earth over 50,000 times, delivering thousands of images and data to study and understand the globe.
Over 4,000 projects in over 70 countries have been supported with Envisat data. ESA said the data archives will continue to be available for users.
Envisat's information is used daily to monitor oil spills at sea, check iceberg hazards, and to provide information for meteorological forecasts.
Image Caption: Envisat is a truly advanced Earth observation satellite with a unique combination of sensors that vastly improve the range and accuracy of scientific measurements of the atmosphere, oceans, land surface and ice. Its total range of capabilities far exceed those of any previous or planned Earth observation satellite. Credits: ESA