Lake Vostok is the world's largest subglacial or literally 'beneath the ice' lake in thw world. It was discovered in 1996 when scientists were looking at radar images of the antarctic ice. The lake is 30 miles wide, 140 miles long and about 3000 feet deep. Scientists think that it has remained sealed off from the outside world for over 35 million years, meaning that no human has ever seen it. Researchers are excited about lake Vostok because the conditions within the lake which is maitained by heat rising from the earth's crust, might mimic those found on some of the more distant planets in our solar system, meaning that if life is found flourishing in Vostok, there may be life elsewhere in space. The problem is how to get into the lake without polluting it and spoiling its pristine waters forever. A russian team have drilled down to within 100 metres of the surface of the water, producing one of the worlds longest ice-cores, which spans over 400,000 years. Excitingly, analysis of the ice has revealed micro-organisms frozen into the ice, which must have come from the lake originally, suggesting that the lake may in fact be teeming with life. So, how to analyse the lake without polluting it...a team of glaciologists from Columbia University led by Robin Bell, have found that although the lake itself is millions of years old, the water in the lake changes fairly frequently by freezing onto the overlying ice sheet, and being replaced from elsewhere. Because the ice overlying the lake is moving - albeit slowly (at about 35 miles every 20,000 years !) - analysis of ice from further away is analogous to analysing the lake itself, they say.