Opportunity takes a moment to survey its recent work: a circular etching made upon an outcropping of rock amongst the dunes of Meridiani Plains.

Both rovers are equipped with a robotic arm that holds three important diagnostic tools mounted on a swiveling “fist”. A microscopic imaging camera, a spectrometer and a rock abrasion tool – RAT, for short. With these tools the rovers are able to bore into rocks to expose layers beneath the weathered surfaces and analyze their compositions for researchers here on Earth.

The photos at left show Opportunity’s arm in action, as seen through its panoramic camera, as well as a three-frame animation from its microscopic imager as it goes in for a closer look at the exposed rock.

This particular collection of flat rocks are called “Cook Islands” by the MER team.

Image credits: NASA/JPL-Caltech