Drilling deep into Antarctic's lost world

Lake Ellsworth last froze over between 200,000 to one million years ago. Photo / Supplied
Lake Ellsworth last froze over between 200,000 to one million years ago. Photo / Supplied

Scientists to probe 3km under ice cap to unlock lake's secrets

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 froze over for the last time between 200,000 and one million years ago.

Although buried beneath a cap of ice about 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 British universities and research institutes has received more than £7 million ($13.9 million) 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.

Researchers want to study the lake bed's sediments, believed to be several metres deep, in the hope of pinpointing 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 is to global warming. A sudden collapse of the West Antarctic Ice Sheet would raise global sea levels by about 4m.

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."

Equipment will be transported to the site during the Antarctic summer with drilling to begin in December 2012. Two sterilised probes will be lowered into the lake once the hole is made with a hot-water drill that will melt the ice as it descends.

HUNT FOR LOST LIFE
How it works
The hot-water drill melts ice as it penetrates the ice sheet.

Once the drilling is complete, scientists have about 24 hours to lower the scientific probes and retrieve samples before the hole freezes again.

The first probe takes samples from the lake's water column and returns them to the surface.

A second probe penetrates deeper into the muddy sediment of the lake's bed to search for living organisms.

Lake Ellsworth
Depth: 90m.
Sediment: 1.8m.
Probe: Lowered 3.2km. Samples are returned for analysis.

- Independent

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