BY PAUL
RECER
AP Science Writer
SAN
FRANCISCO (AP)--Buried under thousands of feet 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, comparable to
Lake Ontario.
Lake Vostok, the largest of the polar lakes, lies beneath
more than two miles of ice and is thought to have a liquid pool with a depth of
about 3,000 feet, 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 60-degree 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.
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 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.
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. |
