Sol 4268, January 26, 2016. Opportunity’s Rock Abrasion Tool (RAT) has bored into the target dubbed Pvt. John Potts for a couple of millimeters. The effort raised a ring of grinding debris around the target, as seen in this false-color Pancam version by Holger Isenberg (click to enlarge).
The rover’s Microscopic Imager has made previous close-up mosaics of this target: first an image of the undisturbed site, then its appearance after a light grind, and finally after the deeper grind.
Opportunity raw images, its latest mission status, a location map. and atmospheric opacity, known as tau.