NASA's Mars Spirit rover is in serious but stable condition this week after failing to carry out commands for a drive across the surface of the planet, agency officials say.Engineers at NASA's Jet Propulsion Laboratory in Pasadena, Calif., are running diagnostic tests aimed at determining why Spirit failed to roll out Sunday on a planned trek across Gusev Crater and why the rover did not record any of its main activities that same day.
The "unexpected behavior" left engineers and mission managers scratching their collective heads during the month that marks the fifth anniversary of Spirit's January 2004 landing on Mars.
Sunday marked the rover's 1,800th "sol" -- or Martian day -- during what originally was planned to be a 90-sol exploration of Gusev Crater, a dry lakebed that once was awash with water.
The rover's twin Opportunity landed that same month on Meridiani Planaum, an ancient plain on the opposite side of the planet. It too is still operating.
Spirit beamed back data Sunday that indicated it had received its driving commands for the day but had not moved. What's more, the rover did not record its activity in computer memory that stores data even when rover power is off.
The next day NASA sent up commands aimed at determining the orientation of the rover in relation to the sun. The rover on Tuesday reported back, indicating it had found the sun but was in fact a bit lost. The rover was not in its expected location. But it apparently stored a record of its daily activities in its so-called "non-volatile memory."
"We don't have a good explanation yet for the way Spirit has been acting for the past few days," Sharon Laubach, chief of the rover's computer command team at JPL, said in a statement. "Our next steps will be diagnostic activities."
NASA engineers think possible causes might include transitory effects from cosmic rays zapping rover electronics.
Whatever the cause, the hiccup appears to have past. JPL Mars Exploration Rover Project Manager John Callas said Spirit once again is operating as expected. Signals beamed back to Earth indicate the rover is in stable condition and is responsive to commands from Earth.
Both Spirit and Opportunity were launched the summer of 2003 from Cape Canaveral Air Force Station.
ABOUT THE IMAGE: Click to enlarge the panorama of Gusev Crater. It was stitched together from images collected by the Spirit rover, which, along with its twin Opportunity, still is operating on Mars five years after arrival on the planet's surface. You also can click the enlarged image to get an even bigger view of rippled sand deposits in a dark field dubbed "El Dorado." At the time the images were collected on the first day of 2006, the Spirit rover was traveling in a downhill direction after reaching the summit of Husband Hill. The latter was named after shuttle mission commander Rick Husband, who was killed in the 2003 Columbia accident with six other astronauts. The sixth anniversary of the accident is Sunday.
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