Measurements taken by the laser altimeter—an instrument for measuring elevation—on NASA's Mars Global Surveyor helped scientists create one of the most detailed topographic maps of the red planet in 1999. The illustration, seen here, shows high elevations in red and lower elevations in blue.
NASA scientists lost contact with the surveyor on November 2, 2006. One hypothesis is that a solar panel became difficult to pivot, depriving the satellite of enough power to communicate with Earth. Researchers are continuing efforts to reestablish contact with the wayward probe, but the outlook is grim.
"Realistically, we have run through the most likely possibilities for reestablishing communication, and we are facing the likelihood that the amazing flow of scientific observations from Mars Global Surveyor is over," Fuk Li, Mars Exploration Program manager at NASA's Jet Propulsion Laboratory in Pasadena, California, said in a statement. "We are not giving up hope, though."
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Image courtesy NASA/Goddard Space Flight Center