WASHINGTON, Jan. 26 (UPI) -- Not since the twin Viking landers began transmitting photos and data simultaneously from the surface of Mars in 1976 have earthbound scientists enjoyed such an ability to probe the red planet in as much detail.
NASA's two new Mars rovers -- Spirit and Opportunity -- are poised to provide the best evidence yet of whether liquid water once flowed across the Martian surface and, with it, the possibility of discovering the first living organisms outside Earth's biosphere.
Opportunity, it turns out, is in an even more favorable position to probe the planet's soil for signs of water and biological activity than mission scientists could have hoped. Based on its first images, sent only about four hours after the craft landed early Sunday morning, EST -- in an area called Meridiani Planum, near the Martian equator -- the rover has come to rest inside a shallow impact crater about 66 feet across. The crater, and a larger one located nearby, will allow Opportunity to examine subsurface rocks without digging.
"We have scored a 300-million mile interplanetary hole in one," said Steve Squyres of Cornell University in Ithaca, N.Y., the principal investigator for the science instruments aboard both rovers.
Scientists selected Meridiani as Opportunity's landing area because it contains extensive deposits of a mineral called gray hematite, which almost always forms in the presence of liquid water. Scientists had hoped for a specific landing site where they could examine both a surface layer rich in hematite and an underlying geological feature. The small crater into which Opportunity has settled appears to have exposures of both.
"If it got any better, I couldn't stand it," said Doug Ming, a member of the rover science team at the Johnson Space Center in Houston.
With the instruments on the rover and just the rocks and soil within the small crater, Opportunity should give scientists the chance to determine the correct theory about the region's past environment, Ming said. Alternative theories include the hematite forming at the bottom of a lake or in a volcanic environment.
The bigger crater, which scientists said could provide access to deeper layers for even more clues to the Martian past, was discovered in images taken by a camera on the bottom of Opportunity's landing vehicle during its descent. The crater, about 500 feet across, is located within about a half mile of the landing site, said Andrew Johnson, an engineer at mission headquarters at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
Opportunity is expected to spend up to two weeks getting ready to drive off its lander, Squyres said. The 150-pound (Martian weight) lander is expected to spend three months or more rolling over the Martian landscape within a mile of its landing site.
Meanwhile, NASA engineers said Monday they have determined the flash memory hardware aboard Spirit is functional, a discovery they said strengthens a theory that Spirit's problem -- which has prevented the rover from transmitting data for nearly a week -- 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," said rover project manager Pete Theisinger.
Spirit sits on a wide, flat, relatively smooth plain within the 95-mile-wide Gusev Crater, an impact basin that scientists think is the site of an ancient lake.
Over the next three months -- assuming no more mechanical problems -- both solar-powered rovers will analyze the rocks and soils around their landing sites. Each is equipped with a mechanical arm containing an abrading tool for wearing away rock surfaces and examining the materials below. The arm also carries twin cameras capable of taking microscopic and spectroscopic images of those materials.
The Mars Odyssey, yet another operational NASA spacecraft currently visiting the red planet, passed its first Martian year -- 687 Earth days -- in orbit on Jan. 11. The Odyssey, which entered Martian orbit on Oct. 24, 2001, has located water ice buried beneath the surface, identified surface minerals, and studied the planet's environment for its potential impact on future human missions -- such as those proposed by President George W. Bush on Jan. 8.
A second NASA orbiter, the Mars Global Surveyor, began its mission on Sept. 12, 1997, has been mapping the planet's surface since then and contributed the images used to select the landing sites for Spirit and Opportunity.
"Before you send any landers to Mars, you want to look at the planet as a whole. We call that 'global reconnaissance,'" said Bob Mase, Odyssey Mission Manager.
The spacecraft were designed to compliment one another, Mase said. "Orbiters can't scrape rocks and look at them microscopically, and rovers cannot traverse and image the entire planet."
The orbiters now also serve as communications relays between the rovers and ground controllers at JPL.
"It's difficult to communicate from the surface of Mars directly to Earth," Mase explained. "You'd need a big antenna and a lot of power. It turns out that the rovers can more efficiently send the information up to the orbiters, which are better equipped to relay the data back to Earth."
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Phil Berardelli is UPI's Science & Technology Editor. E-mail [email protected]
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(Editors: UPI photos WAS2004012651, WAS2004012652, WAS2004012653 and WAS2004012654 are available)
