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Lake Vostok, which lies buried under thousands of meters of ice high on the Antarctic Plateau, is thought to be home to unique habitats and microorganisms. Confirming the existence of life forms and unique biological niches without contaminating the pristine lake waters, however, is a difficult scientific and technical challenge with international ramifications.
According to a paper to be published in the March 21 issue of Nature, the hydrodynamics of the lake may make it possible to search for evidence of life in the layers of ice that accumulate on the lake's eastern shore. Scientists say such a possibility would provide another avenue for exploring the lake's potential as a harbor of microscopic life, in addition to actually exploring the waters of the lake itself.
The paper is authored by Robin E. Bell of Columbia University's Lamont-Doherty Earth Observatory and her colleagues. Their research, which was supported by the National Science Foundation (NSF), reveals that although the lake is perhaps millions of years old, its waters are relatively young. Bell's paper demonstrates that over a period of 13,300 years, all of the water was removed by the overlying ice sheet and replaced from other sources. The lake water captured by the moving ice sheet was carried as layers of ice over Lake Vostok's eastern shoreline, and then eastward away from the lake. Exploring those ice layers, they argue, is equivalent to exploring the lake itself.
"Our study is a critical step in the exploration of Lake Vostok," Bell said. "These frozen lake water samples will record the passage of the ice sheet and the processes across the lake. The data show that the location of the current research station on the lake may not be optimal for biological studies."
Bell added that that "Lake Vostok is absolutely devoid of interference. The youngest water in it is 400,000 years old. It doesn't know anything of human beings, fossil fuels, or plastics. It is a window into life forms and climates of primordial eras."
Radar maps of the Antarctic interior made in 1996 revealed that a lake lay under the ice sheet. Lake Vostok is thought to be one of the world's largest, 48 kilometers (30 miles) wide by 225 kilometers (140 miles) long and 914 meters (3,000 feet) deep. Its waters have been sealed from air and light for perhaps as long as 35 million years under the tremendous pressure of the continental ice sheet.
An ice core -- one of the world's longest -- was drilled by a joint U.S., Russian, and French team at Russia's Vostok Station on the lake's western shore. But coring was stopped roughly 100 meters (328 feet) above what is thought to be the surface of the water to prevent contamination of the lake. The ice layers reveal a 400,000-year environmental record with microorganisms present throughout most of the core.
During the 2000-2001 Antarctic research season, NSF supported a detailed aerial mapping of the lake by specially-equipped Twin Otter aircraft flown by the Support of Office for Aerogeophysical Research at the University of Texas at Austin. The radar sounding, laser altimetry, magnetics, and gravity surveys were a first, non-invasive step to explore Lake Vostok.
Bell and her team analyzed the radar data and determined that the ice formation in the southern half of Lake Vostok holds buckling patterns frozen into the ice sheet as it flows over the lake. Following the trends of the buckled ice patterns, scientists were able to construct movement trajectories across the lake. They then calculated the time it took ice to move from the west side of the lake to the east-20,000 years over a distance of about 56 kilometers (35 miles). By examining the ice flux out of the lake, the team determined that every 13,300 years the ice sheet removes the equivalent of the entire volume of Lake Vostok.
As the ice sheet removes lake water like a continuous conveyor belt, lake waters must be replenished, either by melting of the ice sheet or by subglacial meltwater. The source of this water remains a mystery.
NSF's Office of Polar Programs has established a committee to study the possible scientific exploration of subglacial Antarctic lakes. Read the committee's charge at: http://www.nsf.gov/od/opp/antarct/subglclk.htm
NSF-supported researchers argued in a recent Nature paper that Lake Vostok may contain unique habitats. For more information, see: http://www.nsf.gov/od/lpa/news/press/01/pr0194.htm
Read a report on an NSF-funded 1998 workshop, "Lake Vostok: A Curiosity or a Focus for Interdisciplinary Study?" at: http://www.ldeo.columbia.edu/vostok/
For information about the equipment used by the SOAR aircraft, see: http://www.ig.utexas.edu/research/projects/soar/equip.htm
Read about an earlier NSF-supported research that indicated that microorganisms may thrive in Lake Vostok at: http://www.nsf.gov/od/lpa/news/press/99/pr9972.htm
The International Scientific Committee on Antarctic Research maintains a site on the exploration of subglacial lakes at: http://salegos-scar.montana.edu/