Six days after landing on Mars, the U.S. Opportunity rover has rolled off its landing platform onto the ground, ready to collect scientific data. Mission scientists report that it had earlier sensed the presence of a mineral that suggests liquid water might have flowed on the red planet.
Mission controllers listened to a recording of the British rock group "Who" performing the song Going Mobile as they eagerly awaited Opportunity's confirmation that it had, indeed, gone mobile.
Finally, more than one hour after it was expected to be on Martian terrain, the rover transmitted black and white pictures looking back at the empty lander and showing its track marks in the soil. For mission manager Jim Erickson, that was proof it had completed its two-minute, three-meter drive down the lander's front ramp onto the surface of the Martian crater in which it touched down last Sunday.
"It's on the surface, we've done our first movement, and we're no longer tied to any part of what we brought with us from Earth," he said.
Mr. Erickson says Opportunity's immediate science objectives now will be to map the shallow crater around it, study exposed bedrock within the crater, and eventually crawl over the low crater rim onto the Plains of Meridiani.
Opportunity and its twin rover Spirit on the other side of Mars are looking for geologic evidence that water once flowed on the planet, suggesting it could have supported life.
And, indeed, Opportunity might just have found such evidence, even before taking its first successful drive. Mission scientists say one the rover's instruments confirmed the presence in the crater soil of hematite, an iron-rich mineral that can form in water.
That word, rather than the rover's successful deployment on the ground, was the cause for uncorking a bottle of champagne.
Hematite is the mineral Opportunity came to find after an orbiting U.S. satellite had detected huge deposits of it on the Meridiani plain. Mission scientist Phil Christensen says the hematite signature sensed by Opportunity suggests it formed in temperatures consistent with a water environment, such as a lake or ocean.
"From the data we have so far, it matches best a low temperature origin for that hematite as opposed to a high temperature origin," said Phil Christensen. "A way to form this material is precipitation from water at low temperatures. That is one scenario. I'm not saying that is THE scenario, but that is a scenario."
Mr. Christensen says Opportunity will be able to trace the hematite's origin for sure once it samples the mineral with its full suite of sensitive instruments.
Mission managers expect the twin rover Spirit to be back to normal by Sunday following extensive maintenance of its computer software. An overload of files in Spirit's memory caused it to interrupt science gathering operations more than a week ago. Engineers have erased hundreds of files from the memory in order to clear it for more research activity.