Ten months after touching down on Mars, NASA's Curiosity rover is finally heading toward the primary target of its two-year mission -- Mount Sharp, a three-mile-high mound of layered rock rising from the floor of the Gale Crater landing site.
Tantalizing mineral maps compiled by orbiting satellites provide strong hints that Mars' changing environment is recorded in Mount Sharp's rocks.
Getting there will take months, even by the most direct route and with minimal stops for other scientific studies along the way.
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The base of the mountain is about five miles from Curiosity's present position in Yellowknife Bay, a low-lying area scientists wanted to study first to determine if it had the chemical ingredients for life.
The answer -- a resounding yes -- was in Curiosity's first drill sample. Last month, the rover bore into a second ancient mudstone located about nine feet away from its first target. Results of that analysis are pending.
"They're still working on those results, but what they did try to do ... was to get a feel for the variability of the mineralogy and chemistry by drilling into a spot nearby that looked a little bit different," deputy project scientist Joy Crisp, with NASA's Jet Propulsion Laboratory in Pasadena, Calif., told Discovery News.
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With Curiosity's chemistry lab still working, ground control teams radioed commands on Monday for the rover to turn around and begin the long, slow drive to Mount Sharp.
Even driving straight through, the journey will take 10 months to a year, project manager Jim Erickson, with the Jet Propulsion Laboratory, told reporters on a conference call Wednesday.
Scientists already have picked out three areas for what are expected to be brief studies -- with no drilling -- along the way.
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The sites are a piece of bedrock that sits between areas of mudstones and sandstones, a layered outcrop named "Shaler" and a pitted rock named "Point Lake."
Scientists want to understand how they formed and how they compare with the rocks studied at Yellowknife Bay.
"We're going to keep our eyes open ... as we drive and if we in fact drive past something that's amazing, we might actually turn around and go back and check it out, but there's nothing that we see from orbit that's like some super-compelling clue to life or something like that," Crisp said.