NASA's Mars Exploration Rover microscopic imager onboard Spirit revealed a gap less than half an inch in the imprint left behind in the soil. 3D glasses are necessary to view this image.
This 3-D anaglyph, from NASA's Mars Exploration Rover Spirit, shows a circular imprint left in the Meridiani Planum soil by the rover's Moessbauer spectrometer. 3D glasses are necessary.