Russian researchers pose for a picture after reaching the subglacial lake Vostok. Russian scientists announced they had drilled deep through Antartica's icesheet to reach a pristine lake untouched for tens of thousands of years. Drilling began in the 1970s. The ice sheet covering Antarctica's surface is believed to be some 500,000 years old. Russian media described the breakthrough as the most significant event in Antarctic exploration in a century. An ice core sample was recovered during the drilling. Lake Vostok's water may have been isolated from the rest of the Earth's environment for as long as 25 million years, according to some estimates. Scientists hope that analysis of the ice core, as well as findings by a remote-controlled robot to be sent into the lake, will give a new window on the state of the Earth's environment during the Pleistocene era, a period sometimes referred to as the Ice Age. The liquid lake, which lies on the bedrock below Antarctica's permanent ice sheet, could contain microorganisms millions of years old.

Credit : ARCTIC AND ANTARCTIC RESEARCH INSTITUTE PRESS SERVICE/AFP/Getty