Found buried deep underneath the south pole of Mars, a frozen deposit of dry ice contains nearly 30 times more carbon dioxide than scientists previously though to be buried in the area. This color-coded thickness map estimates the size of the deposits -- that large red circle near the middle is the fairly recent dry ice discovery -- based on observations made by the Shallow Subsurface Radar (SHARED) instrument attached to NASA's Mars Reconnaissance Orbiter.

"Red corresponds to about 600 meters or yards thick; yellow to about 400; dark blue to less than 100, tapering to zero," NASA explained. "The background map, in muted colors, represents different geological materials near the southA Fr pole." The amount of carbon dioxide stored in this space changed dramatically as the planet's axis tilts in various directions. Scientists suspect that when the tilt of Mars' axis increases, much of the carbon dioxide stored near the south pole escapes into the planet's atmosphere, causing its mass to increase.

"The newly found deposit has a volume similar to Lake Superior's nearly 3,000 cubic miles (about 12,000 cubic kilometers)," according to NASA. "The deposit holds up to 80 percent as much carbon dioxide as today's Martian atmosphere. Collapse pits caused by dry ice sublimation and other clues suggest the deposit is in a dissipating phase, adding gas to the atmosphere each year. Mars' atmosphere is about 95 percent carbon dioxide, in contrast to Earth's much thicker atmosphere, which is less than .04 percent carbon dioxide."

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Image: NASA.

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