SAN FRANCISCO, California (AP) -- Buried under thousands of feet (hundreds of meters) of ice in the Antarctic are a series of fresh water lakes unexposed to the open air for millions of years but possibly holding a thriving community of microbes, scientists say.
Researchers probing beneath the permanent ice shield around the South Pole have located at least 76 lakes, including one that is about 5,400 square miles (13,824 square kilometers).
Lake Vostok, the largest of the polar lakes, lies beneath more than two miles (three kilometers) of ice and is thought to have a liquid pool with a depth of about 3,000 feet (900 meters), said John C. Priscu of Montana State University.
In a report Saturday to the national meeting of the American Association for the Advancement of Science, Priscu said the thick blanket of ice has sealed the lake's waters from the open air for perhaps 20 million years.
"This is one of the last unexplored frontiers of our planet," he said.
Water remains liquid in Lake Vostok because the thick ice blanket on its surface insulates against the below zero air temperature of the polar region and traps heat that flows up from the Earth. The heat is enough to keep the lake waters from freezing.
Exotic community of microbes
Priscu said the lake's waters are thought to contain an exotic community of microbes that reached the lake through a 500,000-year process that slowly carries ice from the surface to the waters below.
Ice samples extracted from drill holes punched more than two miles (three miles) through the frozen shield atop the lake contain microbes that are able to survive in a dormant, frozen state for thousands of years. The same type of one-cell animals are thought to live in the lake, Priscu said.
Project could help search for extraterrestrial life
A project now in the planning stage will enable scientists to drill all the way to the Lake Vostok waters and take samples. Plans call for the use of a sterile drilling technique that will prevent contaminating the lake with bacteria introduced from the surface. This will keep pristine the water and microbial specimens that would be sucked up from the ancient lake, Priscu said.
Probing Lake Vostok may help in the future search for life in outer space. Priscu said the lake may resemble subsurface lakes thought to exist on Mars and on Europa, a moon of Jupiter.
The National Aeronautics and Space Administration's long-range plans call for sampling hidden pools of Martian water, if they exist, and to probe beneath the frozen surface of Europa. Both are thought to be the most likely solar system locations for microbial life beyond the Earth.
Techniques learned from drilling into the waters of Lake Vostok one day could be applied to those space missions, said Priscu.
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