Opportunity is inside 'Marathon Valley' on north-facing slopes for improved solar array energy production. The rover is engaged in an in-situ (contact) science campaign investigating the surface target 'Pvt. John Potts' (informally named for members of the Lewis and Clark expedition).

Opportunity is performing successive grinds into the target to prepare a clean surface for elemental analysis by the Alpha Particle X-ray Spectrometer (APXS).

An initial grid by the Rock Abrasion Tool (RAT) had been previously completed, so a survey of the grind was performed on Sol 4248 (Jan. 5, 2016), with the Microscopic Imager (MI) with an initial analysis with the APXS.

Color Pancam panoramas of various targets were collected on Sols 4249 and 4250 (Jan. 6 and 7, 2016).

On Sol 4253 (Jan. 10, 2016), a seek scan with the RAT bit was performed in setup to another RAT grind on a subsequent sol. On Sol 4255 (Jan. 12, 2016), two steps of a deeper grind were performed on the target.

The RAT was left in place so even deeper grinding could be performed later.

As of Sol 4255 (Jan. 12, 2016), the solar array energy production was 452 watt-hours with an atmospheric opacity (Tau) of 0.446 and an improved solar array dust factor of 0.666.

Total odometry is 26.50 miles (42.65 kilometers), more than a marathon.