The second of NASA's twin Mars rovers wrapped up its primary mission on Monday, the 90th full day Opportunity has spent on the Red Planet since landing late in January on a broad, dry plain that it has since discovered was once drenched in water.
NASA expects the six-wheeled Opportunity to continue working through September or longer, possibly tripling in duration its planned mission of just 90 days. It's traveled 2,676 feet (815 meters) so far across Mars.
"We're ready, willing and able to carry on with the extended mission," said deputy project manager Jim Erickson, of NASA's Jet Propulsion Laboratory.
All required tasks are completed
As of Monday, Opportunity and its twin, Spirit, have completed all the baseline tasks NASA required before the space agency would consider the double mission a success. Each identical rover traveled at least 1,980 feet (600 meters), took stereo and color panoramas of its surroundings, drove to at least eight locations and operated simultaneously with its twin for 60 days.
Spirit is already well into its own extended mission. It began on Monday its 112th day on Mars, halfway around the planet from its twin.
The goal of the $835 million double mission is to scour Mars for geologic evidence that the planet once was a wetter place capable of sustaining life.
Opportunity has found that evidence in spades at Meridiani Planum, where rocks suggest a shallow sea covered the region at one time in the distant past.
It's now about 660 feet (200 meters) from Endurance Crater, a broad basin that scientists hope preserves in its rocky rim further evidence of the region's watery past. The crater appears too steep for the rover to enter, Erickson said.
Spirit heading for the hills
On the opposite side of Mars, Spirit has found evidence of only limited amounts of past moisture at Gusev Crater.
Spirit is now about 50 days from reaching the Columbia Hills, where it likely will spend the balance of its mission prospecting for traces of more substantial amounts of water, said Mike Carr of the U.S. Geological Survey.
Scientists believe the Columbia Hills could contain deposits laid down in the past, when a lake may have filled the vast impact crater that Spirit landed in three weeks before Opportunity.
While en route, Spirit recently passed the one-kilometer (0.62-mile) mark, Erickson said.
Mechanical breakdowns and the fierce Martian cold likely will be the death of the rovers, which will remain on Mars once their mission ends.