MICHELE NORRIS, host:
On Mars, a little robot named Spirit has gotten stuck in alien soil. Spirit had been roving around the red planet for more than five years, sending back images and data. But two weeks ago, its six wheels dug into the Martian soil, and the plucky little rover is trapped. NPR's Nell Greenfieldboyce reports on the efforts to get Spirit moving again.
NELL GREENFIELDBOYCE: The Martian soil that's got Spirit isn't like the dirt in your backyard.
Dr. JOHN CALLAS (Project Manager, Spirit and Opportunity Rovers): It's a light, fluffy material. It's kind of like flour, so you can't get much traction in that.
GREENFIELDBOYCE: John Callas is NASA's project manager for both Spirit and its twin rover, Opportunity. He says both of the rovers have gotten embedded in the Martian dunes before.
Dr. CALLAS: Prior to this time, the worst embedding event for either rover was when Opportunity was caught in a dune which we nicknamed Purgatory Dune.
GREENFIELDBOYCE: Opportunity eventually escaped from Purgatory.
Dr. CALLAS: But that was a fully functioning, six-wheeled rover at that time.
GREENFIELDBOYCE: This time, Spirit doesn't have six working wheels. The right front one has been broken for years. The rover has limped along by driving backwards, dragging the wheel. And now, another wheel has stopped turning.
Dr. CALLAS: And there's some reason to suspect that a rock may be jammed in that wheel.
GREENFIELDBOYCE: It gets worse. Callas says that Spirit has dug so far down into the dirt that its little mechanical belly might be resting on some rocks.
Dr. CALLAS: That is a concern, because just as anyone who knows who might drive an off-road vehicle, if you get high-centered on a rock or a stump, you know that you're not getting traction on your wheels because the weight of the vehicle is now on the rock and not on the wheels, where you get your traction.
GREENFIELDBOYCE: Callas and his team will try to take a picture of Spirit's wheels and belly using a camera on the rover's robotic arm that's really supposed to take microscopic photos of dirt. They'll also set up a special sandbox here on Earth to simulate the mess that Spirit's in. They'll put an identical rover in the box of fake Martian soil and test possible ways of getting unstuck. All that will take weeks. Callas says his team is emotionally attached to the rovers.
Dr. CALLAS: You know, we talk to them each day. They're - you know, we interact with them. They're responsive to us. They exhibit personalities. When you discover that one of them is in trouble, then you become very worried, much like, you know, a person would become very worried about, you know, a dear relative if they suddenly became ill or were in a difficult situation.
GREENFIELDBOYCE: If the Spirit rover never again gets to make tracks across Mars, that doesn't mean it's dead. Even if it's stuck forever, it could still do a little science and talk to Earth. But Spirit would no longer be a rover.
Nell Greenfieldboyce, NPR News.
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