Opportunity is on the west rim of Endeavour Crater heading towards 'Marathon Valley,' a putative location for abundant clay minerals less than a mile (about a kilometer) to the south.

The rover is stopped at an interesting geologic unit and conducting in-situ (contact) measurements. On Sol 3853 (Nov. 25, 2014), the rover used the robotic arm to reposition the Alpha Particle X-ray Spectrometer (APXS) for a surface measurement.

On the next sol, the Rock Abrasion Tool (RAT) was used to brush a new surface target, which was then imaged with the Microscopic Imager (MI) and examined with the APXS.

With the Thanksgiving holiday, a multi-sol plan was built to collect Pancam images over the long holiday weekend. However, the rover experienced amnesia events and then a computer reset around Sol 3856 (Nov. 28, 2014).

After the reboot, the rover was no longer under sequence control and was unable to mount the flash (non-volatile) memory. The project restored the rover to normal sequence operation on Sol 3859 (Dec. 1, 2014), but the flash file system remained unavailable. The project prepared for a reformatting of the flash memory on Sol 3862 (Dec. 4, 2014).

As of Sol 3859 (Dec. 1, 2014), solar-array energy production was 468 watt-hours, with an atmospheric opacity (Tau) of 1.376 and a solar-array dust factor of 0.638.

Total odometry as of Sol 3861 (Dec. 3, 2014) is 25.66 miles (41.30 kilometers).