This microscopic image of "Flatrock," taken on the Mars Exploration Rover Opportunity's 43rd sol on Mars, is representative of the science team's goal at the rock outcrop under investigation at Meridiani Planum.

Having already studied target areas starting at the extreme east of the outcrop, Opportunity has made its way westward and is now surveying the "Slickrock" neighborhood that includes "Flatrock." The team is using Opportunity's arsenal of scientific instruments to understand two fundamental things that characterize the outcrop: the detailed layering of the rocks and their chemical composition.

In keeping with the mission's objective to expose martian history through a thorough examination of the rocks, this image illustrates the very fine layered nature of "Flatrock," which preserve a record of sediment accumulation that occurred long ago. Layers are only a few millimeters thick and are accentuated by a distinctive mineral composition that makes them more resistant to erosion. The crystal casts, or vugs, seen so prominently in the beds at "El Capitan" do not occur in this rock.

"Flatrock" was chosen as a target for the rock abrasion tool and subsequent detailed chemical analysis to help the science team build a more complete understanding of how the beds exposed in this crater originated. After careful diagnostic analysis of a failure to successfully grind on sol 42, the rock abrasion tool is ready to make its second attempt on "Flatrock."