Mars rover recovers from apparent bout of 'amnesia'

An aging Mars rover "forgot" about some of its activities on Sunday and failed to follow commands from Earth, but its controllers haven't said whether the glitches are indicators of encroaching senility.

The rover, known as Spirit, acknowledged on Sunday it had received driving instructions for the day from its command centre at the Jet Propulsion Laboratory (JPL) in Pasadena, Calif. But it did not carry out the command, the JPL said in a statement released Wednesday.

The rover also did not record the day's main activities in its memory, the statement said. "It's almost as if the rover had a bout of amnesia," the rover's project manager, John Callas, told the New York Times.

"We don't have a good explanation yet for the way Spirit has been acting for the past few days," said JPL's Sharon Laubach, in a statement. "Our next steps will be diagnostic activities."

Spirit was sent to Mars on Jan, 3, 2004, while a companion rover, Opportunity, landed 21 days later. The rovers were to explore the red planet on a mission that was only to last 90 days, but they are both still going strong.

Sunday marked Spirit's 1,800th Sol (Martian day) on the planet. Each Martian day is 39.5 minutes longer than an Earth day.

JPL has not spoken of old age as a factor, but said that quantum particles known as cosmic rays may have hit the rover's electronics, triggering the malfunctions.

JPL said that by Wednesday the Rover had started behaving normally again.