Satellite tracked as it remains silent

PARIS, April 20 (UPI) -- Optical, radar and laser observations of a European satellite that inexplicably went silent April 8 show it is still in a stable orbit, space officials say.

All efforts to restore contact with the Envisat environmental monitoring satellite have so far failed, the European Space Agency reported from its Paris headquarters Friday.

With help from European and international partners, ground controllers are attempting to determine if Envisat has entered its "safe mode," which could offer a starting point for it revival, officials said.

On April 15 the French space agency CNES turned its Pleiades satellite, which normally provides high-resolution images of Earth, around to capture images of Envisat passing above it at about 54 miles.

Flight specialists and engineers are studying the images to determine if Envisat's solar panel -- the satellite's power source -- is in a position for sufficient exposure to the sun to generate enough power to put Envisat into safe mode.

"These unique images will enable us to analyze Envisat's orientation, which will indicate whether we are able to regain contact with the satellite," Manfred Warhaut, head of ESA's Mission Operations Department, said.