NASA preps Mars rover rescue plan

NASA has come up with a plan to extricate their stuck rover Spirit that's been bogged down in a Martian sand trap since April.

Space agency brains have been conducting a lengthy series of trials using a test rover and sandbox on Earth to figure out the best way of freeing the hindered droid.

"This is going to be a lengthy process, and there's a high probability attempts to free Spirit will not be successful," Doug McCuistion, director of the Mars Exploration program at NASA, said in a statement. "After the first few weeks of attempts, we're not likely to know whether Spirit will be able to free itself."

Spirit got snagged in a place NASA calls "Troy" in the Gusev crater after the rover's six wheels broke through crust on the Martian surface that was covering a bright-toned, slippery sand underneath. Attempts to maneuver Spirit to freedom only made the rover sink deeper into the sand. Engineers then decided to lay of the clutch for a bit and head to their Mars strategy sandbox for some brainstorming.

Although trapped in sand and having lost function of a wheel back in 2006, Spirit and its companion rover Opportunity continue to function much longer than originally expected. NASA had thought the machines would have a life measured in months, but both remain in operation well over five years.

Now after months of planning a rescue effort, NASA has finally decided the first step will be... driving straight ahead. Slowly.

On Monday, NASA will begin transmitting commands telling the bot to rotate its five working wheels forward approximately six turns. Engineers say they expect "severe wheel slippage with barely perceptible forward progress" in the first attempt.

Spirit will then beam home data the next day, and using results from previous commands, engineers will come up with a step number two. NASA said it plans to continue the escape efforts until early 2010.

The rover is believed to be straddling the edge of a 26-foot-wide crater that was filled long ago with slippery, sulfate-bearing sands. Spirit's wheel-turning action is expected to get more tricky as it eases up a small slope away from the crater.

"We'll start by steering the wheels straight and driving, though we may have to steer the wheels to the right to counter any downhill slip to the left," said Ashley Stroup, a Spirit rover jockey and extraction testing coordinator at NASA's Jet Propulsion Laboratory. "Straight-ahead driving is intended to get the rover's center of gravity past a rock that lies underneath Spirit. Gaining horizontal distance without losing too much vertical clearance will be a key to success. The right front wheel's inability to rotate greatly increases the challenge."

Meanwhile on the other side of Mars, Opportunity is still rolling about its merry way and sampling the Martian landscape. ®