Antarctica's Dry Valleys pull water from the air; Mars could do the same

Antarctica isn't completely covered in ice. The McMurdo Dry Valleys almost never see rain and look like a barren desert. Yet photos of the area show patches of moisture on the ground, and geologists believe the soil is wicking moisture out of the atmosphere — which could be happening on seemingly dry planets, too.

What's more the saturated soil patches were found to be a perfect breeding ground for microbes. Scientists theorize that so-called "dry" soils on other planets such as Mars could produce the same effect and may also be teeming with life.

The secret lies in the very salty soil — created from sea spray and other environmental factors. If there is enough moisture in the air and the temperature is just right, this salty soil literally sucks up the ambient moisture. Geologist Joseph Levy from Oregon State noted in his research these soil samples had up to five times more water than other samples in the McMurdo region.

Levy detailed how it works: "The soils in the area have a fair amount of salt from sea spray and from ancient fjords that flooded the region. Salts from snowflakes also settle into the valleys and can form areas of very salty soil. With the right kinds of salts, and enough humidity, those salty soils suck the water right out of the air. If you have sodium chloride, or table salt, you may need a day with 75 percent humidity to make it work. But if you have calcium chloride, even on a frigid day, you only need a humidity level above 35 percent to trigger the response. It's kind of like a siphon made from salt."

It isn't a huge leap for geologists and astronomers to theorize how this might work on Mars. They know that soil and environmental conditions there are similar to those in the McMurdo Dry Valleys and they know there are microbes here on Earth that thrive in saline conditions.

While it is exciting to think about the possibility of life — however small — on Mars, the existence of soil that wicks water from the air is a fascinating geological phenomenon right here on Earth.

Geophysical Research Letters, via io9

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