Mars rovers working overtime
(CNN) -- Martian rovers Spirit and Opportunity are going strong 10 months after they began their geological study of the red planet, mission scientists said Thursday.
And with more sunlight as Mars' springtime begins, activity is picking up.
"The rovers are both in good shape," said Jim Erickson, the rover project manager at NASA's Jet Propulsion Laboratory in Pasadena, California. "Normal science activities are increasing as we continue to get additional power out of the solar panels, primarily because the Martian day is getting longer."
Mission managers briefed reporters on the status of the rovers in a teleconference.
NASA scientists have likened Spirit and Opportunity to robotic field geologists, designed to study the Martian rocks and soil for signs of water. Astrobiologists consider water to be a necessary precursor to life.
Spirit is currently climbing high into the Columbia Hills, which rise above Gusev crater where the spacecraft landed. The crater floor is made of relatively new volcanic rock, formed by lava flows that would have covered any evidence of ancient bodies of water.
After initial study of some so-called basaltic rocks near its landing site, Spirit embarked on a 10-week drive across the crater, more than a mile wide, to reach the Columbia Hills. Scientists hope to find older, more interesting rocks there, and perhaps tell-tale signs of water.
Currently, Spirit is examining a series of specimens that were perhaps formed when wind-borne volcanic ash fell to the ground, mixed with water and eventually formed into layered rock.
"The water evidence that we have at Gusev now in the Columbia Hills, really points, I think, primarily toward groundwater instead of surface water. It's the distinction between water you can draw from a well and water you can swim in," said Steve Squyres, rover principal investigator and a geologist at Cornell University in Ithaca, New York.
"We've got some evidence, I think, of water flowing through the rocks, and changes in chemistry, I don't think we have what any of us would consider compelling evidence for surface water yet."
But the researchers remain optimistic that further exploration of Columbia Hills could yield hard evidence of surface water.
"I wouldn't be surprised as we move uphill that we find a section of the rock, in fact, that was modified in a shallow open-water environment," said Ray Arvidson, rover deputy principal investigator and a geologist at Washington University in St. Louis, Missouri. "We haven't found the smoking-gun evidence for that yet."
Opportunity is exploring in an area called Meridiani Planum on the other side of planet. The rover hit pay dirt early, landing inside a shallow crater ringed in layered rock outcroppings. In April, mission scientists announced Opportunity had found conclusive evidence that a salty sea once lapped the shores of Meridiani.
The rover now is studying rocks inside another, larger crater named Endurance.
Spirit and Opportunity were designed to operate for three months. NASA recently extended the missions for the second time. The rovers, especially Spirit, are aging. Mission managers continue to grapple with a steering brake problem. And a new issue involves a sensor that monitors the status of a layer of insulation that guards against electrical shorts in the vehicle.
"It is an indication that more parts may be showing their age," Erickson said.
Engineers say operations should not be affected in the immediate future.