14 DAY TRIAL // After more than 13 million turns one of the wheals of NASA's Spirit rover has stopped. This comes at the worst possible moment because, as the Martian winter approaches, the rover has to go to the northerly facing slope of McCool Hill, in order to maximize the sunlight falling on its solar arrays.
A few days ago, Steve Squyres, lead Mars Rover Exploration scientist at Cornell University, said: "Our current focus is to drive like hell ? and try to get [Spirit] to safe winter havens before the power situation gets really bad. ... We effectively sort of have to hibernate when we get into the depths of winter." Spirit's solar panels are only producing about 350 watt-hours of electricity these days - only enough to power about an hour of driving.
However, now Spirit faces another challenge: "The wheel is not drawing any current at all," says Jacob Matijevic, engineering team chief for the rovers at the Jet Propulsion Laboratory in Pasadena, California.
Scientists plan to drive the rover backwards, dragging the bad wheel.
This isn't the first time Spirit's wheel has jammed. The same wheel was stuck on 4 January 2004, five months after the arrival on Mars. The problem then apparently had to do with the lubrication of the wheel - the wheel had started to consume very large amounts of energy, double than any other wheel. In 2004, the team on Earth had used the same strategy of driving the rover backwards and after a while the wheel started working again.
But now it's totally stuck and will also exert a considerable drag. In the new conditions, scientists estimate to drive the vehicle at about 12 meters per day.
However, John Callas, the new project manager for the rover mission from the Jet Propulsion Laboratory is still optimistic: "It continues to be an exciting adventure with each day like a whole new mission. Even though the rovers are well past their original design life, they still have plenty of capability to conduct outstanding science on Mars."
"Every day is pure exploration. ? we have been fortunate to have this much," said Jim Rice, a Mars Exploration Rover Project science team member at Arizona State University in Tempe. "If both Spirit and Opportunity died tomorrow we couldn't complain. It would be really sad for a lot of us because we have been living with these machines for years now."
Picture credit: JPL/NASA