All life as we know it needs water. But what organisms can survive when water is all but unavailable? To find out, one scientist is looking at soil from two of the driest places on Earth.
Because the surface of Mars today is bone-dry and frozen all year round, it's difficult to find any place on Earth that is truly Mars-like. But two locations, Antarctica's Upper Dry Valleys and the hyper-arid core of Chile's Atacama Desert, come close. They have become magnets for scientists who want to understand the limits of life on Earth and the prospects for life on Mars.
Jocelyne DiRuggiero, an associate professor of biology at Johns Hopkins University in Baltimore, Maryland, studies samples from both locations. She's interested in the similarities and the differences between the microbial communities that live in these two extreme desert regions. In both places, very little liquid water is present. In the core of the Atacama, years can go by between one rainfall and the next, but it is warm, so when there is precipitation, a significant amount of liquid water is available for a very short time. In University Valley, one of Antarctica's Upper Dry Valleys, the availability of liquid water is limited in a different way. University Valley receives more regular precipitation than the Atacama, but it's so cold there that any precipitation falls in the form of snow and remains frozen.
"What we do in those environments is try to understand who is there, what those organisms might be doing, how they are distributed," and whether the organisms are "really active metabolically," or if instead they're "just sitting there, because they've been brought by the wind."
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Last Updated: 18 April 2011