This image shows a screenshot from software used by engineers to drive the Mars Exploration Rover Spirit up toward the rim of the crater dubbed "Bonneville." The software simulates the rover's movements across the martian terrain, helping to plot a safe course. The virtual 3-D world around the rover is built from images taken by Spirit's stereo navigation cameras. Regions for which the rover has not yet acquired 3-D data are represented in beige. The red darts show target destinations. Red lines indicate the path the rover's wheels will follow to reach the target, and the blue line denotes the path of the rover's "belly button," as engineers like to call it.

In this picture, Spirit is parked at its present location 16 meters (52 feet) away from the crater's rim. Later today, it will drive the rest of the way to "Bonneville."