NASA's Mars Exploration Rover Spirit completed a difficult, rocky ascent en route to reaching a captivating rock outcrop nicknamed "Hillary" at the summit of "Husband Hill." At the end of the climb the robotic geologist was tilted almost 30 degrees. To get the rover on more solid footing for deploying the instrument arm, rover drivers told Spirit to wiggle its wheels one at a time. This animation shows Spirit's position before and after completing the wheel wiggle, during which the rover slid approximately 1 centimeter (0.4 inch) downhill. Rover drivers decided this position was too hazardous for deploying the instrument arm and subsequently directed Spirit to a more stable position before conducting analyses with instruments on the rover's arm.

Spirit took these images with its front hazard-avoidance camera on martian day, or sol, 625 (Oct. 6, 2005).