Carbon dioxide ice at Mars' south pole lies in a delicate tracery of swirls over the planet's surface, as seen by the HiRISE camera aboard NASA's Mars Reconnaissance Orbiter.

This patterned terrain is called "swiss cheese" terrain by researchers, but it also seems reminiscent of traditional Chinese cloud patterns, with distinct fractal overtones. Or does it suggest a cluster of microscopic bacilli?

Unlike Mars' north polar cap, carbon dioxide ice at the diametrically opposed pole remains through all seasons on the red planet. This relatively high-standing smooth material features circular, oval, and blob-shaped depressions. The high-standing areas are carbon dioxide ice with thicknesses of up to approximately 10 meters. The depressions may be caused by the removal of this carbon dioxide ice by sublimation (the change of a material from solid directly to gas).

The complicated shapes arise when neighboring growing depressions intersect.

--NASA/JPL/University of Arizona and SPACE.com Staff

Credit:NASA/JPL/University of Arizona