The rock abrasion tool (RAT) on NASA's Mars Exploration Rover Spirit ground two holes in a relatively soft rock shown here near the base of the "Columbia Hills" field site on Mars. This false-color Pancam image (generated using the camera's 750-, 530-, and 430-nanometer filters) taken on sol 200 (July 25, 2004) highlights the material ground up by the RAT, grayish-blue in appearance in this image. The color of the material excavated by the RAT indicates that the interior of the rock contains iron minerals that are less oxidized than the dust or possibly weathered coating on the exterior of the rock. Scientists speculate that this relatively soft rock (compared to others analyzed by Spirit) may have been modified by water. Small cracks in the surface outside the drill holes may be the result of interactions with water-rich fluids.

<br> USERNAME: shlieven