U.S. Water News Online
PASADENA, Calif. -- NASA scientists said they may send the Opportunity rover on a one-way trip to the depths of a crater on Mars that may have been an ocean at the bottom.
The trip will allow the robot to study stacks of layered rock, which may have formed long ago at the bottom of a salty extraterrestrial ocean. The multiple layers of bedrock that line much of the inner slope of Endurance crater stand in cliffs 16-33 feet high in places.
They are seen in a sweeping color panorama that NASA released at the Jet Propulsion Laboratory. "It's the most spectacular view we've seen of the Martian surface, not just for its scientific value of it, but also for its sheer beauty?" said Cornell University astronomer Steve Squyres, the mission's main scientist.
The bulk of the bedrock is deeper below the surface, and therefore older, than a far smaller outcrop a half-mile away that Opportunity previously revealed to have formed in a wet environment suitable for life.
Scientists know the older rocks now exposed at Endurance crater are different, but cannot yet say what conditions were like when they originally formed. "It's telling us a story about a different environment" Squyres said.
The now-dry region could have been permanently covered by a deep body of water, periodically flooded by a shallow swamp, capped in ice or even scattered with shifting dunes later turned to stone.
Sending Opportunity skidding even part of the way down into the crater, named for the ship that carried Ernest Shackleton1s 1914 expedition to Antarctica, will enable the robotic geologist to study the rocks up close, determine their origin and learn if water played a role.
But the slope and dry soil inside the crater could make it slippery enough to prevent the six-wheeled Opportunity from rolling back out again. Scientists on the $835 million mission said the potential scientific payoff could justify consigning the rover to a crater it could never escape. Opportunity and its twin, Spirit, are expected to last at least through September.
Otherwise, scientists would command the rover to toe-dip into the crater in one or two locations where it is safe to roll in and back out, Squyres said. They would then send the rover to investigate other sites on the surrounding plains it previously studied only briefly or missed altogether.
Opportunity arrived at Endurance crater, a gaping hole 430 feet across, following a six-week trek from its landing site at the far smaller Eagle crater. Both craters have given scientists glimpses below the otherwise flat terrain at the Meridiani Planum site.
Opportunity will spend the next several weeks carefully circumnavigating Endurance along a counter-clockwise route and photographing its interior from multiple angles.
"There are cliffs the rover could roll off and die if we're not careful," rover driver Brian Cooper said.
The crater is up to 66 feet deep, its bottom carpeted in a patchwork of dunes. Even without entering Endurance, Opportunity may be able to analyse rocks cast outward from the crater1s depths and onto its rim.
Halfway around Mars, Spirit was several weeks away from a cluster of hills that could represent a scientific bonanza in its own right. Early analysis of the hills has revealed they are different from the volcanic plains inside Gusev Crater that Spirit is currently traversing.
The hills may have formed in an environment where water played a role, scientists said. "We have some really fantastic things on the horizon for Spirit," said science team collaborator Amy Knudson, of Arizona State University.
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