Growing Pits in the Martian South Polar Ice Cap

This image shows a portion of the South polar permanent ice cap on Mars, which is composed of frozen carbon dioxide (dry ice). This slab of dry ice is a few meters (10-20 feet) thick and is peppered with quasi-circular pits.



The ice is very volatile in comparison to frozen water; it sublimates (evaporates directly from solid to gas) forming carbon dioxide gas when it's exposed to enough sunlight. The ice in this ice cap persists from year to year, yet observations by previous spacecraft ha [...]

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