Latest Spirit News - Updates on the efforts to free the Spirit rover.

Movement from Spirit's Third Extrication Drive

November 23, 2009

Third Extrication Drive Ends With Wheel Stall

Spirit experienced a wheel stall with the right-rear wheel during the second step of a two-step drive on Sol 2092 (Saturday, Nov. 21). This is not the same wheel that stalled on Sol 1899 (May 6), the left-middle wheel. On Sol 2092, the right-rear wheel did not experience a hard stall like what was seen on Sol 1899.  Instead, it stalled because the wheel's progress fell behind the expected rotation rate. The rover had completed about 4 meters (13 feet) of commanded wheel spin before the stall terminated the drive. The center of the rover moved about 4 millimeters (0.2 inch) forward, 3 millimeters (0.1 inch) to the left and about 3 millimeters (0.1 inch) down. The rover suspension stayed within the tighter limits set for the drive, and there was only a fractional change in rover tilt.

The plan ahead for today, Nov. 23, is to sequence a set of diagnostics to explore the right rear wheel stall. The diagnostics will include a rotor resistance test, a possible steering test, a small backward rotation of just the right-rear wheel and a short (about 1 meter, or 3 feet) forward commanded motion of the rover. Resumption of the extrication driving would be no sooner than Wednesday.

Team Sets Plan for Third Extrication Drive

November 20, 2009

Another drive is planned for Spirit on Sol 2092 (Saturday, Nov. 21).

As in the previous drive, the rover will be instructed to drive straight ahead in two 2.5-meter (8.2-foot) steps. This time, however, the right rear wheel will be commanded at a slightly slower speed to allow the right middle wheel to gain more traction. This is to mitigate the potential for a wheelie by the right middle wheel. There will also be tighter limits on the rover's change in direction (yaw) and the angles of the suspension system. As before, not much actual motion of the rover is expected to be observed.

At the conclusion of the commanded motion, the rover will collect three frames from its microscopic imager for a mosaic of the rover underbelly. The rover's panoramic camera will take images of the middle wheels, the navigation camera will take pre-drive and post-drive images for visual odometry, and the front and rear hazard-avoidance cameras will take supporting images.

The drive commands will be transmitted to Spirit Saturday morning. The team expects to have complete drive-related telemetry on the ground on Sunday.

Second Extrication Drive Yields Slight Progress

November 19, 2009

Spirit successfully completed the first step of its planned two-step motion on Sol 2090 (Nov. 19).

After spinning the wheels for the equivalent of 2.5 meters (8.2 feet) in the forward direction, the center of the rover moved approximately 12 millimeters (0.5 inch) forward, 7 millimeters (0.3 inch) to the left and about 4 millimeters (0.2 inch) down. The rover tilt changed by about 0.1 degree. Small forward motion was observed with the non-operable right front wheel, and the left front wheel showed indications of climbing, despite the center of the rover moving downward. These motions are too small to establish any trends at this time.

The drive plan had imposed a limit of 1 centimeter (0.4 inch) motion in any direction. The second step of the drive was not performed, because Spirit calculated it had exceeded that limit.

The data downlink volume from the rover was much better than expected, with all drive-related imagery being received. The team is continuing to analyze results from the drive.

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