The way out. Click for larger. Image Credit: NASA/JPL-Caltech

The plan is to drive Spirit out of trouble by following the tracks it made on the way in  have slowed down a bit.

On November 21, 2009,  the rover was instructed to drive straight ahead in two 2.5 meter (8.2-foot) increments, or at least to get enough wheel spin to get that much distance.  Part of the plan was also to rotate the right rear wheel at a slightly slower rate, the idea being to allow the right middle wheel to get more traction.   Unfortunately a problem developed during the second of a two-step drive and the effort ended with a “wheel stall”.

The “stall” wasn’t a system failure kind of thing; instead the wheel’s progress fell behind the expected rotation rate.  The wheel spun about 1.5 meters (4.9 feet) worth of distance and the actual movement was: 2 mm (0.08 inch) forward, 1 mm (0.04 inch) to the left AND 0.3 (0.01 inch) down according to the latest NASA press release.  I should note the total progress is about a half inch forward as the first drive was a bit more successful.

The good news if there is any, diagnostics on the wheel indicate it can spin freely.  There was another drive over the long weekend and the results were to be analyzed today.

The image above is from the rover and in the lower left we can see soil spun up by Spirit.  The wheel track on the right was made by the one wheel that stopped working earlier in the mission and was being dragged along.  For scale the distance between the wheel tracks is about three feet.

The situation isn’t hopeless, but is heading that way.  Good luck to the drive team, they are going to need it.

Get the latest at the MER webpage.