PASADENA, Calif. — Scientists are closing in on what could be a major discovery for the Mars Exploration Rover program.
NASA’s Opportunity rover appears to have hit a scientific jackpot sitting in a crater at the Meridiani Planum on Mars. Expectations are running high here at the Jet Propulsion Laboratory that the spacecraft should be able to deliver on the holy grail of Mars research: Where’s the water, and could life have ever existed on the Red Planet?
In front of the Opportunity rover is just that — an opportunity to discover a new Mars, one unlike any seen by previous landers.
Images from Opportunity were displayed Tuesday at a morning press briefing. A sweeping look at the unusual rock outcropping near Opportunity was captured by the rover's panoramic camera. Those pictures show layered rocks. But are they the result of volcanic ash deposits, or sediments laid down by wind or water?
Meridiani Planum is rife with deposits of a mineral called crystalline hematite, which usually forms in the presence of liquid water. Thanks to the robot, scientists have the tools to examine on-the-spot surface layers rich in hematite and an underlying geological feature of light-colored layered rock.
The small crater in which the robot rover now rests appears to have exposures of both, with soil that could contain hematite and an exposed outcropping of the lighter rock layer.
Speculation that such an outcrop could be limestone would give scientists the eureka they’ve been looking for — clear evidence of water. With water comes the prospect for biology.
"It's going to be fascinating beyond words to get up close and personal with this thing," Cornell University's Steve Squyres, the principal investigator for rover science, said Tuesday. The expedition could be "the coolest geologic field trip in human history," he said.
Opportunity has tested the three scientific sensing instruments on its robotic arm that will be used for up-close examination of rocks and soil: the microscopic imager, the alpha particle X-ray spectrometer for determining what elements are present, and a Mössbauer spectrometer for identifying iron-containing minerals. All are in perfect health.
But the hardware that could offer the first telltale inspection of hematite and the outcrop’s composition is the mini-thermal emission spectrometer, or Mini-TES.
This instrument sees infrared radiation emitted by objects. It can be used from where Opportunity now rests on the lander deck. That device can determine from afar the mineral composition of Martian surface features, permitting scientists to study select rocks and soil patches in detail.
Mini-TES data acquisition will begin tomorrow, Squyres said. Release of what that instrument finds will take a few days.
The layered outcrop in view of Opportunity has already prompted intense debate.
"If volcanic, all bets are off for liquid water," at the site, said Andrew Knoll, a rover science team member from Harvard University. "If sedimentary, then I think you need liquid water. I wouldn’t think these are wind-borne deposits. It says nothing, necessarily, about the duration of that water."
Whether there has been persistent water at Meridiani Planum remains to be seen, Knoll said. "But certainly what we see in front of us today makes no strong claims for longstanding persistence of water," he added.
"We have high hopes that acquiring Mini-TES data on the outcrop is going to help us in revealing what the material is," Squyres said. The best Mini-TES data will come from the device being placed much closer to the outcrop, during the heat of the day, he told Space.com.
"We’re probably going to get tantalizing hints from a distance. But the beauty of it is that we can go there. We can drive to this outcrop, and we’re going to beat on it with everything we’ve got," Squyres said.
Following its Saturday night landing, Opportunity’s checkout has certified health of the rover, as well as its suite of scientific instruments. Engineers are going through a methodical, step-by-step agenda of readying the rover to wheel itself straight off its lander deck.
But due to the problems with the twin Spirit rover, sitting on the opposite side of Mars, driving Opportunity may be slow going.
Steady progress is being made in getting Opportunity’s wheels "down and dirty," said Jim Erickson, JPL’s Opportunity mission manager. "We're going to get off the lander when it's time to get off the lander," he said.
A glitch in a heater unit, apparently within one joint of Opportunity’s robotic arm, is causing a bit of a problem, having a mind of its own, Erickson said. "But, overall, I’m very happy with the rover’s condition," he told Space.com.
Great care is being exercised in first understanding the problem that crippled the Spirit rover, with lessons learned being applied to Opportunity’s egress and operations at Meridiani Planum.
"We're looking out across a pretty spectacular landscape," said Cornell's Jim Bell, lead scientist for the panoramic cameras on Spirit and Opportunity. "It's going to be a wonderful area for geologists to explore with the rover," he said at a news briefing shortly after Opportunity landed.
The color view shows dark soil that brightened where it was compacted by the rolling spacecraft, and an outcropping of bedrock on the inside slope of the 66-foot (20-meter) crater in which the rover sits.
With the instruments on the rover and just the rocks and soil within the small crater, Opportunity should allow scientists to determine which of several theories about the region's past environment is right, said Doug Ming, rover science team member from NASA's Johnson Space Center in Houston. Those theories include the idea that the hematite may have formed in a long-lasting lake or in a volcanic environment, he said.
Astrobiology research at Meridiani Planum is also possible, said Joy Crisp, rover project scientist. Hydrothermal activity found within this region could mean an environment existed that was favorable for life, she told Space.com. "Life does form in extreme environments here on the earth. But it’s easier to envision life getting started in a place where it was more favorable," she added.
Ray Arvidson, deputy principal investigator from Washington University in St. Louis, said the hematite and other minerals found at Meridiani Planum may offer exciting clues as to past life on Mars.
"If we can pin down either there was hot water or low temperature percolating through this stuff, and we can demonstrate this through the minerals in association with the hematite … then the potential for astrobiology goes way up," Arvidson concluded.
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