Opportunity Straightens Wheel, Resumes Driving

The rover experienced a left-front wheel steering actuator stall on Sol 4750 (June 4, 2017), leaving the wheel toed out by 33 degrees. Our initial attempts to straighten the wheel failed to yield any results and were suggestive of a mechanical cause for the stalls (in the steering actuator).

Fortunately, however a repeat of the diagnostics on Sol 4763 (June 17, 2017), added a twist that may have made a difference.

In addition to attempting to actuate the steering at different voltages in a straightening (toe-in) direction, the team also commanded very small (half degree) actuations in the toe-out direction in between the straightening attempts.

While these also stalled, the very last straightening attempt appeared to break free from whatever was impeding it and steered the wheel to straight.

This very good result was tempered by the fact that we still do not know for certain what the cause of the stalls was and whether the problem could reoccur.

Therefore, Opportunity will be exercising a precautionary partial moratorium on usage of the steering actuators for the foreseeable future. Specifically, this directs no front usage of steering actuators and only rear usage as circumstances might demand. Instead, tank turning and steering will be used wherever possible.

The first nominal drive under these new restrictions was executed on Sol 4766 (June 20, 2017). While the drive ended early, this was due to a visual odometry failure unrelated to steering and was still successful in traversing about 46 feet (14 meters) out of a goal of 18.

As of Sol 4766 (June 20, 2017), the solar array energy production was 364 watt-hours with an atmospheric opacity (Tau) of 0.699 and a solar array dust factor of 0.540.

Total odometry is 27.88 miles (44.86 kilometers).