An ambitious mission to search for life that has been buried beneath 3km of ice in an Antarctic lake for hundreds of thousands of years begins in earnest this week.
A team of British scientists and engineers will start transporting the 70 tonnes of drilling equipment needed to penetrate the West Antarctic Ice Sheet and sample the lake's water column and mud-covered floor. They hope to discover a "lost world" of microbial lifeforms that have survived in solitary isolation from the rest of the biosphere when Lake Ellsworth, which is nearly the size of Lake Windermere, froze over for the last time between 200,000 and one million years ago.
Although buried beneath a cap of ice some 3.2km thick, the lake's water remains liquid because of the immense pressure from the weight above and the small amounts of geothermal heat coming from the ground below.
Scientists believe there is a strong possibility that unique viruses, bacteria and fungi may have survived in this cold, dark environment for thousands of years without any interaction with the outside world.
A consortium of UK universities and research institutes has received more than £7m in funding from the Natural Environment Research Council and the British Antarctic Survey in Cambridge to collect the first biological samples from one of the frozen continent's 387 known sub-glacial lakes.
The researchers also want to study the lake bed's sediments, believed to be several metres deep, in the hope of pinpointing the periods in geological history when the West Antarctic Ice Sheet disintegrated and reformed.
They believe this could lead to a better understanding of how vulnerable the ice sheet now is to global warming. A sudden collapse of the West Antarctic Ice Sheet would raise global sea levels by about four metres.
But the most scientifically challenging part of the mission is to insert sterilised probes into the lake's water column and muddy sediment without contaminating the lake with bacteria and fungi from above. "This is a pristine environment and we don't want to disturb it," said Professor Martin Siegert, of the University of Edinburgh, who is the principal investigator on the Lake Ellsworth Programme.
"For almost 15 years, we've been planning to explore this hidden world. It's only now that we have the expertise and technology to drill through Antarctica's thickest ice and collect samples without contaminating this untouched and pristine environment."
The equipment will be transported to the site this winter – the Antarctic summer – ready for drilling to begin in December 2012. Two sterilised probes will be lowered into the lake once the hole is drilled through the ice with a hot-water drill that will melt the ice as it descends from the surface.