This before-and-after pair of images of the same patch of ground in front of NASA’s Mars Exploration Rover Opportunity 13 days apart documents the arrival of a bright rock onto the scene. The rover had completed a short drive just before taking the second image, and one of its wheels likely knocked the rock — dubbed “Pinnacle Island” — to this position. The rock is about the size of a doughnut.
The images are from Opportunity’s panoramic camera (Pancam). The one on the left is from 3,528th martian day, or sol, of the rover’s work on Mars — December 26, 2013. The one on the right, with the newly arrived rock, is from Sol 3,540 — January 8, 2014. Much of the rock is bright-toned, nearly white; a portion is deep red in color. Pinnacle Island may have been flipped upside down when a wheel dislodged it, providing an unusual circumstance for examining the underside of a martian rock.
The site is on “Murray Ridge,” a section of the rim of Endeavour Crater where Opportunity is working on north-facing slopes during the rover’s sixth martian winter.