London, Feb 15 : Scientists have developed a mini model of Antarctica's Lake Vostok - the world's largest subglacial lake, which has given clues to the way its waters circulate, and hence on where scientists should drill to find ancient life.
A report in New Scientist has said that Mathew Wells and John Wettlaufer built this one metre-long and 30-centimetres-wide model of Lake Vostok in their lab at Yale University, US.
According to the researchers, water trapped in vast subglacial lakes like Laek Vostok moves in ways that are not seen anywhere else on Earth.
Lake Vostok's waters are thought to contain microbes that have been isolated from the atmosphere for at least half a million years. The vast lake is sealed off from the outside world by a lid of ice, almost 4 kilometres thick, the pressure of which keeps the lake's waters liquid even at around -3 °C.
The researchers' findings on how water may circulate within this lake should help scientists in their quest to find life in one of the planet's most extreme environments.
Understanding how water circulates within Lake Vostok could help, as currents move vital nutrients needed for life. Nutrients in subglacial lakes are hard to come by, so life in Lake Vostok will be localised to where nutrients are available, said the report.
As for the mini model is concerned, the researchers put a layer of insulation on top of the water to mimic the ice cap, heating pads to reproduce the sources of heat to the lake.
Injecting dyes into the water revealed how the water moved under these conditions. The water described large circles around the lake, warming up at the bottom, rising to the surface then cooling down and dropping back down to the bottom.
But when the researchers rotated the tank to mimic the Earth's spin something entirely new happened.
An array of tight vortices appeared, which moved the dyes in columns from the top of the tank to the bottom and vice versa. The researchers calculate that in the real lake, the vortices would be about 10 to 30 metres across.
The dyes moved slowly, suggesting that if the lab model is correct, it should take between 20 and 30 days for free-floating bacteria to move between the bottom and the top of Lake Vostok.
According to the report, whether or not there is life in Lake Vostok may depend on whether it is home to bacteria that can survive the month-long ride from top to bottom.
But it is clear that the best place to look for life will be at those boundaries, where food will be most plentiful, said the researchers.