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miércoles, 20 de mayo de 2009

Robot Rescue Party Aiding Mired Martian Rover

NASA’s Spirit rover is stuck in the Martian soil, but the agency’s full complement of robots in the neighborhood are working to free it.

For the past two weeks, Spirit has been mired in loose terrain near an area known to NASA as Home Plate. If you’ve ever driven a remote-controlled car into a molehill, you can understand the rover’s predicament. It’s up to its wheels in dirt and may be “high-centered,” or perched on its undercarriage, spinning its wheels.

But there’s some hope. From orbit, the Odyssey orbiter has begun downloading extra data from Spirit in hopes of figuring out what’s happened. Meanwhile, Opportunity tested out maneuvers for taking self-portraits of its chassis, so that Spirit can learn how to snap a shot of its own positioning. And perhaps most importantly, a wheel that NASA engineers thought had died still has a pulse. A recent test of its capacity to handle current came back with positive results.

“This is not a full exoneration of the wheel, but it is encouraging,” said John Callas, project manager for rovers at NASA’s Jet Propulsion Laboratory. “We’re taking incremental steps.”

Both Spirit and Opportunity have been traveling the midsection of Mars for more than 20 times the planned 90-day length of their missions. While Opportunity had its own five-week sand vacation in 2005, recently Spirit has had more trouble. In January, the rover malfunctioned for reasons that still aren’t clear.

As Wired Science reported yesterday, the next generation of rovers will be even more mobile than their predecessors — and less prone to getting stuck in difficult terrain.

But for the time-being, Callas’ team has to figure out how to get Spirit out. Matters are complicated by the failure of one of Spirit’s six wheels, which he says, “greatly compromises the mobility of the robot.” To figure out what to do, Callas is building a replica of the Martian terrain in Pasadena.

“We want to literally landscape it the way the rover is on Mars,” Callas said. “We have an engineering copy of the rover here that is virtually identical to the rover on Mars. We’ll bury it like Spirit is and then experiment on trying to get the rover out.”

To do that, it’ll take a few tons of sandy Martian-like material and then some excellent sculpting.

800 Martian days after it landed on the planet, the Mars Spirit Rover is acting strangely.

The unexpected bad behavior isn’t strange like HAL, but it could be strange like an old laptop. For some unknown reason, the rover has had on-and-off problems accessing its permanent memory and completing standard operations like driving around taking pictures of Mars.

"We don’t have a good explanation yet for the way Spirit has been acting for the past few days," said the Jet Propulsion Laboratory’s Sharon Laubach, chief of the team that writes and checks commands for the rovers.

Spirit’s fellow Martian rover Opportunity appears to be in fine condition. Both bots have been roving the midsection of Mars for more than 20 times the planned 90-day length of their missions. The NASA-JPL team will run diagnostic tests on the rover this week. The problems could be short-lived. It’s possible that cosmic rays hit some vital electronics, causing them to temporarily malfunction.

But if there is a serious problem with Spirit, it would come at an inopportune time. The next (bigger, badder) rover mission, the Mars Science Laboratory, was recently delayed for two years and won’t launch until fall of 2011. (The MSL recently received the nickname, Rickroll, when fans of Rick Astley took over a Wired Science poll.)

The Mars rovers’ project manager, John Callas of JPL, remained upbeat, however.

"Right now, Spirit is under normal sequence control, reporting good health and responsive to commands from the ground," Callas said.

UPDATE : NASA mission controllers said Thursday that Spirit continues to function normally, but no explanation of its strange behavior over the last week has been found. They plan more diagnostic tests for Friday, focusing on the Rover’s internal measurement system, a Wii-controller like combined gyroscope and accelerometer that tells Spirit where on Mars it is. NASA officials are hopeful that the robot will be back in action this weekend.

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