Opportunity is on the west rim of Endeavour Crater near "Marathon Valley," a putative location for abundant clay minerals now only about 394 feet (120 meters) away.

The project is preparing to mask off the troubled Bank 7 sector of the Flash file system with a new version of the flight software (FSW) after the project completes the near-term science campaign.

The rover has sampled an unusual rock composition in the rim region near Marathon Valley. The near-term plan is to sample more rocks exhibiting the purple and bluish coloring that is apparent at this site.

On Sol 3950 (March 5, 2015), we began robotic arm work with a Rock Abrasion Tool (RAT) brush and Alpha Particle X-ray Spectrometer (APXS) measurement of "blue rock" target "Sgt. Charles Floyd."

Due to Ultra High Frequency antenna data volume constraints we postponed doing a full Microscopic Imager (MI) mosaic on the target until Sol 3952 (March 7, 2015). Depending on the results of the APXS measurement, the team was considering a follow-up grind on Sol 3955 (March 10, 2015).

However as the subsequent analysis showed that Sgt. Charles Floyd appeared similar to another rock that we encountered out on the plains, and since it seemed to be very hard and would cause excessive wear on the RAT grind bit, we decided to move on to a "purple rock" target instead.

On Sol 3955 (March 10, 2015), we bumped to target "Sgt. Nathaniel Pryor." While the bump was successful, wheel straightening knocked the Instrument Deployment Device slightly out of alignment with the target and required us to do a small tank turn, which has been implemented in the Sol 3957 (March 12, 2015), plan.

As of Sol 3956 (March 11, 2015), the solar array energy production was 577 watt-hours with an atmospheric opacity (Tau) of 0.658 and a solar array dust factor of 0.725.

Total odometry is 26.15 miles (42.09 kilometers).