ROBERT SIEGEL, host:
The Mars rover Opportunity is moving again. Scientists have finally succeeded in digging it out of a very sticky martian sand dune. NPR's Patricia Neighmond reports that engineers had to be extremely precise and persistent to maneuver the robot back onto solid ground.
PATRICIA NEIGHMOND reporting:
This was a bigger challenge than it might seem. Martian sand, it turns out, is nothing like sand here on Earth. It's finer, flakier and stickier. It clung to the six wheels of the rover and offered absolutely no traction. Steve Squyres is the lead scientist for the rover missions.
Mr. STEVE SQUYRES (Lead Scientist, Rover Missions): The worst thing you want to do in a situation like this is go blasting out of the dune that you're stuck in and crash right into another one nearby and get stuck in that one. So we--rather than taking a risk that we would sort of leap out of this thing and proceed to get stuck in something else, we did it in small, safe increments. And that's the reason it took a while.
NEIGHMOND: Nearly five weeks, to be exact. Under Squyres' supervision, engineers at NASA's Jet Propulsion Lab in California mixed up tons of fine-powdered earthen clay and sand to try to replicate sand on Mars. Then they drove an exact replica of the Mars rover into the dune. Rick Welch is mission manager for the project. After figuring out how to get the rover unstuck here on Earth, engineers then sat down at their computers to send orders to the rover on Mars. But as Welch says, it was still a different story.
Mr. RICK WELCH (Mission Manager): We would command 10 meters, and then we would get back the result that we only moved 5 centimeters, just 2 inches, when we told the rover to go almost 30 feet. That was a surprise that it was moving so slowly, but it was forward progress. And so we continued that strategy. And then on Saturday, after commanding over 190 meters of travel, we finally broke free and drove about a total of two meters from where--the position we were actually stuck in.
NEIGHMOND: Persistence, says Welch, finally paid off. Ironically, now scientists want to turn the rover around--it was driving backwards when it got stuck in the sand--and go back to the dune. Using its robotic arm, they'll scoop up some sand for analysis. Lead scientist Squyres says that at this point the rover's surrounded by this sand, and if they want to continue exploring, they'll have to learn how to deal with it.
Mr. SQUYRES: We're obviously going to proceed much more slowly and carefully. We were traveling at very high speed for this vehicle at the time that we encountered this problem. So we're going to proceed a lot more deliberately as we work our way south.
NEIGHMOND: After learning what they can about the sand, scientists will then begin leading the rover south toward a large crater they've named Erebus. The Erebus crater is the largest one to be explored thus far. It appears to be shallow and eroded, and Squyres says he's hoping there might be exposed bedrock that could offer tantalizing new information about the red planet's geologic past. Patricia Neighmond, NPR News.
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