Drilling for life in an Antarctic abyss

The secrets hidden in one of the most remote environments on the planet are about to be revealed. Scientists working in Antarctica are set to drill down through more than three kilometres of ice to reach a fresh water lake that has not seen the light of day for up to half a million years.

The €10 million-mission has taken 16 years of planning, the work of at least 100 engineers and scientists, and required the transport of almost 100 tonnes of equipment across 16,000 kilometres on to the West Antarctic ice sheet.

The goal is to determine whether life of some kind can survive in Lake Ellsworth, one of about 360 lakes that lie under the thick Antarctic ice sheet. If life can struggle along there, in frigid conditions, completely isolated from the sun and at pressures as intense as at the bottom of the ocean, it will likely be found in other extreme environments on other planets and moons across our solar system.

Bore-hole drilling is set to start in the next few days and water and sediment samples from Lake Ellsworth could reach the surface in about 10 days. However, nothing is certain when working in Antarctica’s harsh environment, says the mission’s principal investigator, Prof Martin Siegert of the University of Bristol.

He has championed the project since the late 1990s, and now that five days of continuous bore-hole drilling is about to start there is no shortage of nervous tension. “It will be a wonderful moment to get the samples back,” Siegert says. “I just want everything to work.”

It has taken years to reach this point, with support from the British Antarctic Survey, the UK National Oceanography Centre in Southampton and eight UK universities. And although there has been a cast of 100 involved, just 12 people including Siegert have gathered on the ice above Lake Ellsworth to accomplish the task.

One might wonder why invest all the money and effort to bring back samples of water and muck off the lakebed, but Prof John Parnell of the University of Aberdeen is in no doubt about the importance of the mission.

Success will tell us much about just how rugged life forms can be. “Ultimately we need to know the limits of life, not just on Earth but in a wider context,” he says. Life colonises every nook and cranny we can find on Earth so they are expecting this to also be true of Ellsworth. “If they have not been able to colonise this environment it will be very surprising.”

The researchers are expecting to find microorganisms in the water and possibly in the first few centimetres of lake bed sediments. “If there is no life in the lake it will be the first time we have found a body of fresh water that doesn’t support life,” says Siegert. “We are not expecting that. These are not naturally sterile environments and they have available all that is needed for life.”

The sediments will tell another tale, one that could prove very important for us in the context of climate change. “We are looking at sediments on the floor of the lake and what we would like is a history of the West Antarctic ice sheet,” Siegert says.

Glaciologists believe the massive western ice sheet is at risk of collapse. “We don’t know when it disappeared in the past, but it did, and at times the lake was clear of ice,” Siegert says. The sediment should provide a record of climate, telling the scientists about the conditions under which the ice could completely disappear.

This is why scientists want to sample Ellsworth, but how they are going to achieve it is a remarkable story of invention and precision engineering. “It is an amazing project to be involved in,” says Dr Matt Mowlem, head of ocean technology and engineering and lead engineer on the water-sampling probe at the National Oceanography Centre in Southampton.

Everything about it is unique to the Ellsworth project. The team designed a hot-water, high-pressure “drill” head that will melt its way down through three kilometres of ice, leaving them a perfectly round water-filled bore hole 36cm across.

Lights, cameras, probe: A fascinating piece of boring engineering

Once through to the lake the team will have just 24 hours to send down separately the water sampling probe and the sediment corer. Time is short because the hole will refreeze, its diameter closing up by 0.6cm an hour. The two five-metre-long probes are only about 20cm in diameter so there should be time to get all the samples and clear the hole before it seals itself up.

Aside from these challenges, the scientists had to prevent lake contamination by micro-organisms from the surface. Elaborate cleansing methods were used on the probes and the drill head, leaving the rig as clean as an operating theatre.