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New life-related geology beckons Opportunity rover

Posted: July 19, 2009

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The Mars Reconnaissance Orbiter (MRO) has found clay-bearing rocks lying directly in the path ahead for the Mars rover Opportunity, giving the rover the unexpected chance to sample a totally new rock type that could have provided a wet, warm, and non acidic habitat for the formation of early life on Mars.

Massive Endeavour crater dwarfs Victoria crater (top left) that Opportunity spent two years exploring. Credit: NASA/JPL
The finding increases stakes for Opportunity to reach the site which scientists at Cornell University now find has the same high priority geologic character as those on the final landing target list for the Mars Science Laboratory ( MSL) rover "Curiosity" planned for launch in 2011.

"This discovery by MRO is very important because clays are an indicator of aqueous processes , formed at a neutral acidity level says Steve Squyres, Mars rover principal investigator Cornell University.

"The clays we have found are not only indicative of abundant water, but also a watery environment more suitable for life," Squyres told Spaceflight Now. The rover team never thought areas within their reach harbored such potential - but new hope beckons.

MSL's development, however, is increasingly as perilous on Earth as its mission to Mars will be. Its funding reserves are increasingly low just as its development team finds additional hardware problems.

Those problems include new assessments that show MSL nuclear power system will fall short of what will be required to keep critical actuators warm and to operate the rover's Sample Analyses at Mars (SAM) instrument as intended.

"Rover nuclear power system design does not meet present mission requirements, requiring additional battery capacity and possibly addition of a solar array," according to a July 9 review at NASA Headquarters.

The SAM instrument development itself, is also lagging at the Goddard Spaced Flight Center, the report finds.

But in a rare lucky break for the search for evidence of life on another planet, Opportunity will be able to directly sample the newly found phyllosilicate formations, if it can survive for the next 12-18 months, the time needed to drive ten more miles to the location.

It will take that long for the rover to drive to Endeavour crater where it has been aimed anyway for the last 9 months. Endeavour, is nearly 15 mi. in diameter with spectacular rims, already visible on the horizon to Opportunity's imaging systems.

North Rim of Endeavour crater is imaged by Opportunity still 12 mi. distant when image was taken. Rover has now closed to within 10 mi. of newly discovered clay rich soil meaning neutral acidity water was present possibly supportive of life. Credit: NASA/JPL
Both "Oppy" and the rover Spirit, have been operational for more than 5 years on the Red Planet now 170 million mi. from Earth. Opportunity has already driven 10 miles in the last 5 years, while Spirit has driven about 6 mi. in its more rugged landscape.

Sprit also remains stuck in water altered soils where it became bogged down several weeks ago on the opposite side of Mars. Jet Propulsion Laboratory engineers are working with an engineering duplicate of the rover they have placed in specialized soil mix for driving tests on how to free it. One promising mode is a crab maneuver where all six wheels are pointed toward the left or right side to drive out of the trap sideways.

"Within days of landing on Mars, Opportunity discovered evidence for a past aqueous environment. But this environment was characterized by high acidity and low water activity both significant challenges for astrobiology," says James Wray, at Cornell who led the assessment of what the Reconnaissance Orbiter findings could mean for Opportunity.

"We analyzed images of Endeavour from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on MRO. Spectra of portions of the crater rim contain absorption bands diagnostic of phyllosilicates," says Wray.

"Images of the clay-bearing surfaces from the MRO High Resolution Imaging Science Experiment (HiRISE) reveal layering and a range of polygonal textures similar to those observed in phyllosilicate-bearing rocks elsewhere on Mars .These textures are seen virtually everywhere bedrock is exposed on the Endeavour crater rim, suggesting the bedrock is pervasively altered," he says.

Neither Opportunity nor Spirit has been able to sample such clay-rich rocks indicative of early Martian geology when the planet was warmer and wetter and potentially more habitable to organisms beginning to thrive on Earth at the same time after the planets' formation. It had been thought such terrain had to be left for MSL to explore.

Opportunity's instruments deployed on flat rocks enroute to Endeavour. Credit: NASA/JPL
Opportunity's landing site was selected for the hematite rich plane discovered by the Mars Odyssey thermal emission spectrometer instrument. The MRO imagery also provides conclusive evidence that Endeavour crater was blasted out by a meteorite billions of years before Meridiani plane filled with more acidic water. By then the planet was much colder and less hospitable to life.

Although wind blown deposits have buried part of Meridini, its original crater rims and part of its older floor remained exposed above the level where the hematite plane flooded or blew in around it eons later.

"Investigation by the rover could illuminate outstanding questions regarding how these phyllosilicates formed, potentially shedding light on regional or global-scale processes of aqueous alteration predating the acidic conditions that produced the sulfate-rich rocks Opportunity has studied to date," says Wray.

"If Opportunity reaches it with its Cornell/Athena instrument payload still largely functional, the Miniature Thermal Emission Spectrometer and the Mossbauer spectrometer could each independently confirm the presence of clays, possibly determine their hydration and iron oxidation states, and identify associated minerals.

The Alpha Particle X-Ray Spectrometer could reveal major and minor element chemistry, while the Pancam and Microscopic Imager could document possible sedimentary textures, grain sizes and shapes to constrain the processes that emplaced these phyllosilicate-bearing rocks," says Wray.

Although it may remain largely unspoken outside the halls of the rover control center at JPL in Pasadena, if Opportunity reaches such clays, the team will also be looking in the rock formations for tiny fossils - life on Mars - that may have formed in previously warmer, wetter conditions that now beckon for rover exploration 10 mi. ahead.

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