for National Geographic News
Don't don your swim trunks just yet, but deep beneath the Antarctic ice sheets are at least 145 lakes that may be teeming with microscopic organisms similar to those that could be thriving beneath the ice on Jupiter's moon Europa, according to scientists.
The lakes lie beneath blankets of ice up to 2.5 miles (4 kilometers) thick and are considered one of the great unexplored frontiers on Earth.
Scientists are engaged in a long-term program to understand what type of life may survive in the lake water, sediments below, and ice above. Current efforts are focused on the ice above, which includes lake water frozen to the ice sheet bottom, known as accreted ice.
"The glacial ice should provide the biological seed for the lakes and the accretion ice should reveal actual genomes within the lake itself," John Priscu, an ecologist with the department of land resources and environmental sciences at Montana State University in Bozeman, said in an email from the Antarctic.
Martin Siegert, a glaciologist in the school of geographical sciences at the University of Bristol in the United Kingdom, said scientists first recognized the existence of the lakes in 1970. The most recent inventory, to be presented at the December meeting of the American Geophysical Union in San Francisco, California, puts the number of known lakes at 145.
"This is not the total number that will be found there. There are large regions yet to be surveyed comprehensively and the only way this number is going to go is upwards. I would estimate there are 300, 400, maybe 500 lakes," he said.
According to Priscu, the west Antarctic is particularly intriguing. "It is beginning to sound like a complex hydrological system, complete with continental size river basins like the Mississippi," he said.
Antarctic researchers identify the presence of lakes beneath the miles-thick Antarctic ice using a technology known as radio echo sounding, which works in the same manner as radar used to detect aircraft flying high in the skies.
"High-frequency radio waves at an airport fired up into the air bounce off anything with a change in the electric properties of the medium," Siegert said. "In the case of an aircraft, there are differences in the electrical properties of the air and the metal of the aircraft."
Radio waves also travel easily through ice sheets. So researchers began flying over the Antarctic in the 1970s firing radar down into the ice sheets, noting changes in electrical properties when the waves bounced off what lay beneath the ice.
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