Good news for anyone planning a Halloween Party on Mars — the Red Planet is very well stocked with dry ice, at least for a few more thousand years.
New data from the Mars Reconnaissance Orbiter shows a massive deposit of frozen carbon dioxide at the planet’s south pole. Buried beneath a layer of regular ice, the dry ice is reported to be approximately the size of Lake Superior. It is believed to be the remains of Mars’ ancient atmosphere, which, according to earlier space probes, was once very similar to Earth’s.
But the CO2 won’t stay frozen forever. Mars has a “wobbly” orbit, which tilts the poles closer to the sun every hundred thousand years or so. This heats the planet and converts the CO2 into gas, nearly doubling the density of the current, very thin atmosphere. The gas freezes again when Mars straightens out and cools down.
The extra CO2 in Mars’ atmosphere wouldn’t be enough to do much warming, says [Roger Phillips of the Southwest Research Institute in Boulder, Colo., lead author of a report on the discovery], but it’s not without effect. For one thing, the thicker air would be enough to allow water to exist on the surface at lower elevations. The oceans of Mars won’t return, and probably not the rivers — but creeks and ponds would be possible.
Scientists studying the Orbiter’s discovery have observed spots in the south polar ice cap that appear to be “slumping,” which suggests the dry ice is starting to evaporate again. This corresponds with changes in atmospheric pressure measurable by comparisons to previous data.
The CO2 cycle of atmospheric gas to dry ice — and back again — also occurs on a much smaller scale on Earth. Global warming deniers often point to this cycle to dismiss the impact of civilzation’s high carbon emissions. The new Mars data confirms that some climate change is indeed natural, but anyone hoping to use the Red Planet to appeal to the Red States won’t have much basis for their argument. Conditions on Mars and Earth are too different today. Who knows how big our dry ice deposits could be in a billion years?
Click here for a collection of high resolution, never-before-seen photos taken by the Mars Reconnaissance Orbiter.
Image credit: Wikimedia Commons