Mars rovers on 'brand new mission'
By Kate Tobin
(CNN) -- Two interplanetary Energizer bunnies, NASA's Spirit and Opportunity rovers, keep going and going. The pair of robotic explorers are now well into their extended missions on the surface of Mars.
Program scientists briefed reporters on the status of the rovers during a news conference at NASA's Jet Propulsion Lab in Pasadena, California.
"This is basically a brand new mission starting right now," said science team member Jim Rice. "Come along with us, we're fixing to go on another great voyage of exploration here and see what we can find."
NASA has likened both rovers to robotic field geologists, designed to explore the Martian landscape for evidence of water. Spirit, which landed on Mars in an area called Gusev Crater five months ago, has traveled nearly two miles from its landing site.
It's now approaching an area called the Columbia Hills complex, where mission scientists plan to study boulders and layered rock outcrops. They expect those rocks to be much older and perhaps more interesting than the relatively young volcanic rocks that litter the floor of Gusev Crater. Spirit should arrive there in a couple of weeks.
"We're on 'bonus time,' as we say," remarked mission manager Matt Wallace. "We're into extra innings now."
Spirit's twin, Opportunity, is exploring an area on the other side of the planet called Meridiani Planum. The rover has spent the last month driving around the southern rim of the massive Endurance Crater, imaging rocks inside the crater from every possible angle.
There are a number of tantalizing targets of study inside the crater, including a rock called Karetepe. But mission scientists say they're still deciding whether to risk a trip inside. Engineers have been conducting experiments in a test bed facility at the Jet Propulsion Lab to see how steep a slope the rover can climb on sandy and rocky surfaces.
"If we go in, there is a possibility, independent of how much testing we do, that we might not come out," Wallace said. "So the risk/benefit equation is still being worked. We're spending a lot of time talking about it, and hopefully that will converge and we'll end up making a decision."
Mission scientists announced in March that Opportunity had found evidence that a shallow, salty sea once lapped the shores of Meridiani, laying down a characteristic ripple pattern on the rocks during their formative years. That makes the Opportunity landing site a prime destination for future space missions designed to look for signs of life.
NASA said both rovers are healthy. Mission controllers had to troubleshoot two software glitches in the past few weeks that caused Spirit to unexpectedly shut itself down. The rover is back to normal now. And Opportunity is now regularly powering down to "deep sleep" mode at night, a move designed to keep a heater stuck in the "on" mode from draining the onboard power supply during the bitterly cold overnight hours.
Frequent use of the "deep sleep" mode will likely eventually lead to the loss of one of the rover's key scientific instruments, the miniature thermal emission spectrometer.
NASA hopes both rovers will remain functional until at least September.