The effort to free NASA?s Spirit rover, currently mired insand on Mars, will begin in earnest today, when engineers team send the first escapecommands to the stuck robot to try to move out of its trap late tonight.
Spirit has been stuck in the Martian dirt since April, when droveinto a spot of soft terrain called "Troy" back in April.
Mission managers have spent the past six months devisingstrategies to move the rover out of the sand pit. They tested them withmodel rovers back on Earth that are essentially replicas of Spirit andits twin, Opportunity.
Rover drivers decided that the best strategy would be tohave Spirit backtrack, moving forward to retrace the tracks that brought itinto its current predicament. (The rover's broken right front wheel has meantthat Spirit's primary mode of driving is backwards.)
NASA announcedthe strategy last week, and the rover team plans to write the commands forSpirit to drive out of Troy today and send them up to the rover in the weehours of Tuesday morning.
The results of the drive are expected to come back sometimeon Tuesday, after which the team will spend at least a day analyzing thembefore sending up any more commands.
The precarious nature of the embedding ? Spirit's wheels aredug in to their hubs, one wheel has stopped spinning and a rock is sittingunderneath the rover's belly, possibly even touching it ? means that the teamhas to be very careful about any movements they make with the rover.
"This is by far the most complicated and complex"embedding the team has had, said John Callas, project manager for the MarsExploration Rovers (MER) at NASA?s Jet Propulsion Laboratory in Pasadena,Calif.
Callas said the team expects any motion the rover makes tobe small at first and the process to take several weeks.
If Spirit has not yet been freed by the time or the rovers'annual review rolls around in February, NASA officials will weigh whether tokeep trying, to keep Spirit where it is and continue doing science there or tocall it quits.
The team is upfront about the chances of getting Spirit out.Ray Arvidson, deputy principal investigator for the rovers (and based at Washington University in St. Louis) has told fans of Spirit to be "hopeful, butrealistic."
And whether or not Spirit makes it out, NASA considers themission an unqualified success, as both MER rovers have last 24 times as longas initially planned, as they come close to rounding out their sixth year onthe red planet.
- Video ? Free Spirit: Plotting an Escape
- Mars Rover FAQ: The Martian Lives of Spirit and Opportunity
- Video - Spirit: The Little Mars Rover That Could