NASA scientists have found a way to make the Mars rover work again, but it is still not known what caused last week’s system glitch.
After running a series of diagnostic tests on the Mars rover, it responded to commands and drove about one foot this past Saturday, according to information released by NASA .
A longer drive had been planned but it was cut short when one of Spirit's front wheels became stuck behind a rock. The rover was expected to drive around the rock on Monday.
The latest news comes about a month after testing and hardware problems delayed the launch of a new SUV-size Mars rover, the $2.3 billion NASA Mars Science Laboratory from next fall to 2011.
Spirit and its Mars rover companion, Opportunity, have been working on the red planet for five years, far longer than their initial estimated life span of three months.
The Mars rover Spirit started acting erratically a little more than a week ago. NASA said Spirit sent information back to Earth indicating that it had received its driving commands for the day, but it did not move. And on the same day, the rover failed to record its activities, as it normally does, into its own memory.
Then within the next two days, the rover's controllers sent the robotic machine instructions to find the sun with its camera, in the hopes that that would enable Spirit to reorient itself. The rover reported back that it had found the sun but not in its expected location.
Then late last week, NASA engineers said they the robotic explorer was healthy and responding to commands again, though they were still trying to diagnose the initial problems.
Now, days later, they are still unsure what caused the glitch.
"We may not find any data that will explain what happened ... but there's no evidence that whatever happened then has recurred on subsequent [Martian days]," said Jacob Matijevic, a member of the rover engineering team at NASA's Jet Propulsion Laboratory , in a statement. "One possibility is that a cosmic-ray hit could have temporarily put Spirit temporarily into a mode that disables use of the flash memory."
The two rovers are among the best pieces of technology that NASA's Jet Propulsion Laboratory has ever built, said Bruce Banerdt, project scientist for the Mars Exploration Rovers, in a previous interview.
The rovers, which are working on the Mars equator but on different sides of the planet, had their five-year anniversary on Mars last month. The machines have been sending and receiving information from Earth every day, with a team of about two dozen programmers and engineers uploading code to guide the rovers' movements and aim their cameras. All of that information travels about 200 million miles one way, taking anywhere from five to 21 minutes to travel from one planet to the other.