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NASA selected Opportunity's general landing area within a region called Meridiani Planum because of extensive deposits of a mineral called crystalline hematite, which usually forms in the presence of liquid water. Scientists had hoped for a specific landing site where they could examine both the surface layer that's rich in hematite and an underlying geological feature of light-colored layered rock. The small crater appears to have exposures of both, with soil that could be the hematite unit and an exposed outcropping of the lighter rock layer. "If it got any better, I couldn't stand it," Dr. Doug Ming, a rover science team member, said. The instruments on the rover should allow scientists to determine which of several theories about the planetary region's past environment is right, Ming said. Those theories include that the hematite may have formed in a long-lasting lake or in a volcanic environment. An even bigger crater, which could provide access to deeper layers for more clues to the past, is located nearby. Images taken by a camera on the bottom of the lander during Opportunity's final descent show a crater about 150 meters (about 500 feet) across likely to be within about one kilometer or half mile of the landing site, according to Dr. Andrew Johnson of JPL. Johnson is an engineer for the descent imaging system that calculated the spacecraft's horizontal motion during its final seconds of flight. The system determined that sideways motion was small, so Opportunity's computer decided not to fire its lateral rockets as it descended. Squyres presented an outline for Opportunity's potential activities in coming weeks and months. After driving off the lander, the rover will first examine the soil right next to the lander, then drive to the outcrop of layered-looking rocks and spend considerable time examining it. Then the rover may climb out of the small crater, take a look around, and head for the bigger crater. But first, Opportunity will spend more than a week -- perhaps two -- getting ready to drive off the lander. Engineering data from Opportunity returned in relays via NASA's Mars Odyssey orbiter early this morning and at midday indicate the spacecraft is in excellent health, said JPL's Arthur Amador, mission manager. The rover will try its first communications directly to Earth this evening. Encouraging developments continued for Opportunity's twin rover. Engineers have determined that Spirit's flash memory hardware is functional, strengthening a theory that its main problem is in software that controls file management of the memory. "I think we've got a patient that's well on the way to recovery," Project Manager Pete Theisinger said. The main task for both rovers in coming
months is to explore the areas around their landing sites for
evidence in rocks and soils about whether those areas ever had
environments that were watery and possibly suitable for sustaining
life.
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