The U.S. space agency NASA says its twin Mars rovers appear healthy enough to last at least five more months. It has extended their water-seeking odyssey now that the Spirit rover has completed its 90 day prime mission and the Opportunity robot is approaching that goal.
Mars mission managers say Spirit and Opportunity this past week completed nearly all of their original objectives and in most cases exceeded them. The goals called for them to make a 360-degree panoramic photograph of their surroundings, grind into and inspect at least rock, travel at least 600 meters, and visit eight locations between them. They have done almost all of that in their search for signs that water once flowed on Mars.
Spirit mission manager Jennifer Trosper says her rover has traveled 17 meters farther than the 600 meter goal while Opportunity, which launched later, still has a little more than two weeks to do so. "Spirit has accomplished all those objectives and mission success has been met," she said. "So the warrantee is up and we'll see what types of things happen as Spirit continues on."
Along the way, Opportunity found evidence of an ancient expanse of shallow salt water, perhaps a sea, that scientists say could have supported life. Spirit has turned up signs that water influenced the formation rocks on the other side of Mars, although scientists have not found signs that it was extensive surface water.
NASA has now authorized the vehicles to operate through at least the middle of September, another 250 days for Spirit. The manager of the U.S. Mars exploration program, Firouz Naderi said that no one knows if the rovers will last that long, but all systems look good so far. "While we have all the expectation that we'll get to September, we look at this extended mission purely as bonus science," he said. "It may go to the end of 250 and then be healthy and go beyond that, or something may happen in the middle of June and one or two of the rovers may come to a dead stop."
Mr. Naderi, a native of Iran, says not enough martian dust will have built up on the rovers' solar panels by mid-September to prevent them from producing power, nor will the shortening martian days have that effect, either. Testing of their motors and other components showed before launch that they should be able to work that long and tolerate repeated extreme daily temperature fluctuations on the barren planet.
The NASA official says if the rovers are still running in mid-September, the space agency will make another decision on extending their mission yet again.
In the meantime, the mission team has switched from living on Mars time back to Earth time. Following the martian clock made coordinating rover operations easier, but because the martian day is nearly 40 minutes longer than on Earth, employees had a slightly different work schedule each day. NASA officials says that such an agenda takes a physical and emotional toll on the mission team, so it wants them to learn how to conduct future, longer Mars surface missions according to Earth time.
Jennifer Trosper says the schedule change is a big relief. "It's just been nice to come to work at a normal time, eat at normal times, see people people that you would normally see," she added. "The only thing I don't like about Earth time is the traffic!"
The Mars rover control center is in Pasadena, California, close to the second largest U.S. city, Los Angeles.