August 24, 2005

Mars Rovers Make Progress

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Despite seemingly hopeless long treks, and an encounter with a dangerous sand dune, the Mars rovers made major advances and found evidence of water in new regions of the planet this summer.

The Spirit rover reached the summit of Husband Hill last weekend after weeks of climbing to find what Prof. Jim Bell, astronomy, calls “interesting evidence for the action of small amounts of water.” The discovery came after a dry period, when Spirit found no signs of water as it moved toward the peak.

Spirit started its long ascent in the Columbia Hills, named in honor of the Columbia astronauts, earlier this summer. The landscape was richer than that surrounding the hills, and “the geochemistry and mineralogy were much more interesting,” said Elaina McCartney, a Cornell-based space mission planner with the rover team.

Sulfur-rich minerals were detected on Husband Hill, proving that there was water present at one time. “We don’t know how much water there was, or when it was there. But these minerals provide solid evidence that liquid water has interacted with the rocks and soils of Husband Hill long ago,” Bell said. “Now we’re trying to puzzle the pieces together like geologist detectives.”

“Blueberry” markings along the surface of the hill have also caught the attention of rover scientists because they are very different than in other regions. On the rover update website, Prof. Steve Squyres Ph.D.’78, astronomy, wrote that these gray hematite objects provide even more evidence that water was present in the Meridiani Planum area at one time. Spirit will now take pictures of the surrounding landscape to look for other craters or peaks before moving on in early autumn.

Spirit’s sister craft, Opportunity, had a more difficult few months than its counterpart as it was stuck in the sand dunes near Victoria Crater for more than a month in late spring. NASA team members simulated the sand trap at the Jet Propulsion Lab in Pasadena to figure out how to get the craft free. Working for five weeks, the scientists finally maneuvered the rover’s wheels so it could get enough traction to move out of the dune. Opportunity was finally freed on June 4.

Cornell senior research associate Rob Sullivan helped with the simulation and now advises other rover planners on how to avoid getting stuck again. In order to do this, he uses images sent from Opportunity’s panoramic camera, or Pancam, to learn why these particular dunes were different from others they have encountered. Bell is the Pancam team leader.

McCartney said it was a very frustrating time for all involved, joking that the ordeal was comparable to “getting a car out of an Ithaca snowdrift.” The area in which the rover got caught is now called Purgatory Dune.

Once again on the move, Opportunity is nearing the edge of the Erebus Crater, more than 100 meters in diameter. The crater is brighter than the surrounding hematite-rich landscape, and scientists are anxious to see its geological makeup. If the rover can safely scale the side of the crater, it will study the different layers of rock to learn about the planet’s history.

The two rovers have lasted on Mars for much longer than initially expected. NASA predicted they would have a lifespan of about 90 days when they reached opposite sides of Mars in January 2004; they have both been working for more than 560 Martian days (a Martian day is just under 25 hours) and scientists will continue to collect data from them for as long as possible.

Archived article by Melissa Korn
Sun Senior Editor