Bright Soil Near 'McCool' While driving eastward toward the northwestern flank of "McCool Hill," the wheels of NASA's Mars Exploration Rover Spirit churned up the largest amount of bright soil discovered so far in the mission. This image from Spirit's panoramic camera (Pancam), taken on the rover's 788th Martian day, or sol, of exploration (March 22, 2006), shows the strikingly bright colors and large extent of the materials uncovered.