"We're kind of sad to leave the crater but the job now is to explore the plains and put the picture of a shallow, salty ocean into better perspective," said Ray Arvidson, deputy principal investigator for the rover mission, of Opportunity's travels during a press briefing held today at NASA's Jet Propulsion Laboratory in Pasadena, California.
The rover spent the last two months studying a rock outcrop and surrounding soil near its landing site in Eagle Crater, a small depression in the vast Meridiani Planum region on Mars. The rover's observations that led scientists to conclude the region was covered in with salty water sometime in the past.
A slippery exit
Opportunity, now in its 61st day on Mars, had some trouble getting out of Eagle Crater at first. When the rover tried a head-on run out of the crater last week the robot hit some soft sand and slipped back. But after a second attempt, on a more oblique course, the rover successfully left the crater.
Researchers stopped Opportunity five times on the way out, each time using the rover's arm instruments to study the soil, paying close attention to the presence of hematite-rich spherical objects dubbed "blueberries" by researchers.
"We found that there is a higher concentration of hematite at the crater rim than at the center," said Gstar Klingelhfer, payload element lead for the rover's Messbauer spectrometer. "This is the most dense hematite content that we've seen on Mars."
Opportunity's handlers are waiting for the rover to send home a final panoramic image of Eagle Crater before directing the rover to make a 700 meter-dash to another, larger, crater dubbed Endurance in the hope that there will be an even larger rock outcrop to study.
Spirit at Mazatzal
After completing its 81st day on Mars, Spirit is at the rock target Mazatzal, where it has already used its arm-based instruments to brush off bright dust, revealing dark rock underneath. NASA scientists plan to drill a hole about eight millimeters into the rock and use a pair of spectrometers attached to Spirit's arm.
Mission managers have long-duration plans for Spirit as well.
Scientists are going over plans for a 90-day journey to the Columbia Hills, which lie about 2.3 kilometers away from its current location at Bonneville Crater. Scientists are already looking for interesting places to stop along the way and conduct quick observations before reaching the hills themselves. There they hope to spend at least 10 days studying to region.
"It's an open plain, and one might expect it to be a boring thing to cross," said Mer science team member Larry Crumbler of Spirit's hillward path. But scientists have identified more than six interesting features on the way to the hills that Spirit didn't see on its first long journey to Bonneville.
"So it won't be a long continuous drive, we'll actually get out and do some tourist things along the way," Crumbler said.
Shift change
In order to prepare for the long haul of an extended MER mission, researcher and scientists at JPL will switch over completely to an Earth time schedule. To date, mission personnel have had to set their clocks to the local time on Mars for both Spirit and Opportunity.
"We will be able to reduce the number total number of people working on the missionprobably by something greater than half," said Matt Wallace, Opportunity mission manager at JPL, adding that the cut back in personnel is possible because researchers have become more efficient at mission planning.
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