British scientists flew into Antarctica at the weekend to begin an extraordinary search for life in a stretch of water the size of Lake Windermere buried under three kilometres of solid ice.
The researchers join a team of engineers who have set up camp on the West Antarctic ice sheet, where the December sun shines night and day, and temperatures plunge far below freezing.
In the coming days, the team will use a sterile hot water drill to bore down to the subglacial Lake Ellsworth and retrieve samples of water and sediments that may have been isolated from the rest of the world for a million years.
Should life be found lurking in the depths of the lake, it will have evolved in isolation for at least 100,000 years, but probably much longer. Scientists want to know first whether life can endure such harsh environments. If it can, the next question is how.
The answers will further our understanding of life on Earth, and inform searches for life elsewhere in the solar system, such as in the ice-capped ocean of Jupiter's moon Europa.
"Extreme environments tell you what constraints there are on life," said Mike Bentley, a geologist on the team at Durham University. "If we find a particular set of environments where life can't exist, that creates some bookends: it tells you about the limits of life."
Lake Ellsworth is one of more than 360 subglacial lakes in Antarctica that formed when gentle heat from the planet's interior melted the base of an overlying glacier. On Earth, less hospitable environments are hard to imagine. Any organisms that live here are cut off from the air above, and must contend with subzero conditions, few nutrients, complete darkness, and intense pressure.
The search for life is only part of the motivation to probe Lake Ellsworth. Through studies of sediment cores drawn up from the lake bed, scientists hope to learn when the overlying glacier waxed and waned, and how the local environment changed over time.
The team will spend this week preparing for a three-day drilling operation, due to start on 12 December. To bore into the lake, engineers made a 3.4km-long hose that is strong enough to bear its own weight and a nozzle on the end. The hose is supplied with ultraclean water heated to 90C, which blasts out of the nozzle and melts its way through the ice sheet.
Once the team have broken through to the lake they will have 24 hours to sterilise the entrance to the hole with intense ultraviolet light, and lower equipment into the water to collect all the samples they need before the hole refreezes again.
"It's pretty exciting to have to do all your science first time within a 24-hour or so window with no chance of a second go," said Dr Matt Mowlem, who developed submersible technology for the project at the National Oceanography Centre in Southampton.
The scientists will collect water samples from various depths of the lake, which is 150 metres deep, by lowering probes that stand nearly six metres tall and weigh 400kg. The first samples are expected on 18 December. The team has two designs of corer to grab sediments from the lake bed.
Speaking by phone from a small tent in Antarctica, Chris Hill, a British Antarctic Survey engineer who is managing the programme, told the Guardian about the harsh conditions and the weeks ahead.
"It's bloody cold. When we wake up in the morning, the insides of the tents are around -15 or -20C. Today it's -25C outside and there's no wind. It gets right through to your bones," he said.
The team will spend six weeks on the ice. The focus of the camp is a tent that houses the kitchen, dining area and office facilities, around which are a handful of smaller tents for sleeping in. In a blizzard, visibility drops to about five metres.
"Once we've started drilling we can't stop, or the pipes will freeze and that's that. We have to go to a 24-hour shift pattern for a week and a half to two weeks, and no matter what the weather does, we have to keep going," he said.
All the equipment has been tested, but no amount of field trials in Britain can fully replicate the conditions the team will face in Antarctica. "Everything we are doing is new," said Hill. "We're drilling deeper than anyone has drilled with hot water, we're drilling cleaner than anybody has ever drilled before, and we're launching two instruments that are custom-developed and designed for the job. What keeps me awake at night? Everything."
The team will remain in Antarctica until January, and spend the festive season at work on the ice. Bleak and challenging as the project is, those who had to stay behind are still envious of their colleagues. "They are going to have a pretty cold Christmas, but I'd love to be there," said Mowlem.
This article originally appeared on guardian.co.uk
