Post date: Sep 24, 2012 2:35:37 PM
WEST ANTARCTICA (RECENT) (BAS) - British scientists are making final preparations for an ambitious scientific mission to go deep into the heart of the frozen continent to collect samples of water and sediments from an ancient lake buried beneath three kilometres of ice.
A three-way race to find life in subglacial lakes deep beneath Antaectica and answer questons about the region's last ice melt is heating up, as a British-based team of scientists prepares to begin its ambitious mission.
The 12-man team of scientists, engineers and support staff from the British Antarctic Survey (BAS) and the National Oceanography Centre (NOC) will make the 16,000 kilometre (9942 mile) journey from Britain on October 22. They hope to reveal clues about Earth's past climate and discover life forms that may live in subglacial Lake Ellsworth on the West Antarctic Ice Sheet.
The team designed and created a titanium water-sampling probe and sediment corer capable of being lowered down a three kilometre borehole in the ice made by a custom-built hot-water drill.
By early December the team will have prepared the field camp and will be in place to begin the 100 hours of non-stop, hot-water drilling required to create the borehole through to Lake Ellsworth. The team will then have just 24 hours to sample the lake before the borehole re-freezes and re-seals the lake. Typical working conditions will be in temperatures of minus 25°Celcius and wind speeds averaging 25 knots.
During a briefing last week Andy Tait, who helped design the hot water drill, explained to the team that they would use a 1.5 megawatt boiler to melt "an awful lot of snow" to provide 90,000 litres of water for the hot-water drill. The drill will pressurise the water to 2,000 psi (pounds per square inch) and then pump it at 210 litres per minute through a 3.5km bespoke hose to create a 360mm wide borehole.
Programme manager Chris Hill explained how the drill will work. "You heat a large body of water, then you pump it up at high pressure through a bank of pumps. Then you squirt it out a very long hose. That's the simplistic version. Obviously the scale of what we're doing, drilling through 3.2 kilometres of ice means that the hose has to be huge, which means an enormous winch to control the weight of the hose, the boiler required to heat that amount of water in that amount of time is one and a half megawatts of power, and then on top of all of that to ensure we keep everything clean we run all of that water through a pharmaceutical level filtration process."
The majority of samples uncovered will be sent back to Britain to various institutions for analysis, as Hill explained. "We've gone to great lengths to get the samples and to keep them in a very pristine condition.
It would be a real shame if we were to try to analyse them too quickly on site without the proper protocols and equipment in place. So we plan to ship the majority of the samples back to the UK where we have specialist lab facilities set up at different universities and institutes around the UK that can properly handle and take care of these samples."
Teams Russia and the US are also taking part in a three-way race to discover life in the most remote and extreme environment known on Earth. In February, after 20 years of stop-go drilling, Russia was the first to pierce through 3,769 metres (12,365 ft) of solid ice to Lake Vostok - the largest and most isolated of 360 known subglacial lakes, untouched for some 15-25 million years. But critics say the drilling technology used by the Russians relied on kerosene and anti-freeze to keep the borehole open and that any samples retreived are likely to be contaminated. Russia will begin collecting samples next year. By contrast, the U.S. and British missions will both drill with hot water that is filtered and UV radiated, which they say is environmentally safer.
Hill says the idea of the teams being involved in a race has been over-hyped, but admits that his team would like to get their analysis done first. "It's looking at the moment like we may well be the first to sample a sub glacial lake, and that's great news for us, and we're really looking forward to getting those results back," he said.
Martin Siegert, of the University of Bristol and principal investigator for the mission, says the team expects to find if microbial life had evolved in the darkness under the ice. This might increase the chances of finding life elsewhere in the solar system, such as on Jupiter's ice-swathed moon Europa. The scientists aim to use a hot water drill and take samples in a sterilised titanium container.
"What we're trying to do in this experiment is test that relationship between water and life in a very extreme place, and we expect life to be there. The questions that we think we're going to be able to answer are how is life living there, is it thriving, is it on the edge of existence, what is the concentration of life, are there bits of the lake where there are more life than other parts, and what do the sediments have in the role of that," said Siegert.
Siegert says no one knows the age of the West Antarctic ice. It might have broken up in naturally warmer periods about 125,000 years ago, 440,000 years ago or a million years ago - all times when sea levels were higher than today. He said sediments on the bed of the lake, which is several hundred metres below sea level and buried under 3.2 km of ice, may include remnants of ancient seashells that could be dated to reveal when the ice sheet last broke up.
He said: "One of the things we regard the West Antarctic ice sheet as being is that we think it's unstable, that it may be susceptible to changes in the future. So we think it's at risk of change, but to really understand that risk you have to work out the last time the west Antarctic ice sheet disappeared, and whenever that was we'd look at the environmental conditions which led to its decay and work out how close we are to those environmental conditions today, and in so doing we can work out the physical change ahead of us. But we don't know the age of the Antarctic ice sheet and we don't know the age when it last disappeared. Now we're hoping that sediments on the floor of the sub glacial lake will give us a clear understanding of when that might be."
Sub-glacial lakes are formed by heat from the Earth melting the bottom of the ice. Experts say the West Antarctic ice sheet over the lake contains enough ice to raise world sea levels by 3-5 meters if it ever broke up - a threat to low-lying areas from Bangladesh to Florida, from Buenos Aires to Shanghai.