Million years old Antarctic Lake Ellsworth to be drilled soon
Subglacial Lake Ellsworth is buried beneath nearly 3 kilometers (2 miles) of ice on the South Pole and it remained isolated for possibly half a million years. It is located on West Antarctic Ice Sheet about 70 km west of the Ellsworth Mountains at (78°58’34”S, 090°31’04”W). Lake Ellsworth experiences some of the world’s most extreme weather with wind chills reaching -70°C and wind gusts up to 160 km/h (100 mph).
Sediments on the lakebed are likely to reveal vital clues about the history of life in the lake and the ancient history of the West Antarctic Ice Sheet, including past collapse. The extreme explorations will be a test to determine if water correlates with life, even under extreme pressure, cold and nutrient deficiencies.
Lake Ellsworth drill mission
The team of scientists and engineers from British Antarctic Survey (BAS) and the National Oceanography Centre (NOC) will live and work on location for around 6 weeks. The temperature will average -25 degrees Celsius (13 degrees Fahrenheit) and the wind will whip up to speeds of 50 km/h (30 mph). Hundred tons of equipment have already been sent from the U.K. to the middle of Antarctica. The field team will leave for Antarctica around the middle of October, hoping to be on site around 10th November. If all goes to plan, the first samples will be retrieved around 18th December 2012.
Lake Ellsworth was mapped in detail by scientists using seismic survey techniques discovering a hidden lake 12 km long, 3 km wide and 150 meters deep (Credit: British Antarctic Survey)
An UK team of 12 scientists and engineers will use hot-water drilling “clean technology” to make a borehole through the ice to the lake below in October. They will then lower a titanium probe to measure and sample the water followed by a corer to extract sediment from the lake. The unique 5 meters long water-sampling probe will collect 24 water samples (50 ml) at different lake depths. It will also capture the top layer of sediments where the lake-floor meets the water. The sediment corer can extract a core up to 3 meters (10 feet) long. The corer is strong enough to penetrate even the most compacted glacial sediments to extract a core sample.
Once engineers on the British team drill down to the lake, the researchers will have only 60 hours to collect water and sediment samples before the bore hole re-freezes. Re-freezing of the borehole will reduce its diameter by around 0.6 cm per hour.
The team will use a continuous 3.4 km hose that is strong enough to support its own weight and that of the drill nozzle and an industrial-sized 1.5MW boiler to heat 30,000 litres of hot water (90°C) for the drill. Three large surface tanks (each with a 5 metre diameter) to store water above freezing point in temperatures as low as -20°C. Several large-scale generators will provide electrical power to the drill. The hot water drill will use and recycle the existing ice on site for the drilling fluid, minimising the potential for contamination of the lake.
An earlier attempt to use a hot water drill in Antarctica failed when the hose, made up of 400m sections, broke apart under the weight of the water. This time, the hose is a single length.
Antarctica is home to 387 known subglacial lakes. Subglacial lakes exist in most parts of the continent, because low levels of heat from the Earth’s interior is enough to melt the base of the ice sheet. Some lakes are known to discharge their water from time to time, which can flow several hundred kilometers into other lakes. The water beneath the ice remains liquid because of small levels of heat from the Earth’s core coming up through bedrock and from the insulating effect of several kilometres of ice above.
Some subglacial lakes may be as old as the ice sheet. The age of the water within the lakes will be as old as the ice which melts into them, which in West Antarctica is around 150,000 years. Subglacial lake-floor sediments could yield vital clues to past climate and could also help us understand the extraterrestrial environment of Europa (one of the moons of Jupiter). The largest and most well-known subglacial lake is Lake Vostok on East Antarctica.
Location of subglacial lakes that are about to be drilled
Organisms found in Antarctic lakes so far are typically close relatives of bacteria found in aqueous water that have evolved mechanisms to grow in the cold. Some microbes, called psychrophiles, found in polar ice, glaciers and deep ocean waters can withstand frigid temperatures as low as minus 15 degrees Celsius (5 degrees Fahrenheit). They consist mostly of bacteria, fungi and algae, and contain enzymes that are adapted to function at low temperatures.
Michael Madigan, professor emeritus at Southern Illinois University, who has studied microbial ecosystems in Antarctic lakes found with his colleagues sulfate-eating life in Lake Fryxell, covered in 3 to 5 meters (10 to 16 feet) of ice. In November and December of 2011, Madigan collected snow and ice samples around the South Pole and is currently trying to find out if he can enrich any life in below-freezing conditions.
A core sample from Kamb Ice Stream in western Antarctica contained abundant microbes. However, that core sample may have been compromised since it was stored for over a year at 4 degrees C (39 F) instead of at freezing or below freezing temperatures.
Other Antarctic subglacial lake drill projects
A separate expedition of 13 researchers on the WISSARD (Whillans Ice Stream Subglacial Access Research Drilling) project will start drilling in October as U.S. scientists look for life under another system of lakes and rivers underneath the ice in western Antarctica. The American team will examine a complex series of lakes and rivers called Lake Whillans and the Whillans Ice Stream beneath a thick coat of ice that drains into the ocean. They expect to find a microbial system on the sediment surface that makes a living in the dark by fixing carbon dioxide and mining rocks from energy minerals.
The Russian Antarctic Expedition that in February successfully drilled into Lake Vostok in East Antarctic, under nearly 4 km (2.5 miles) of ice, will join this two missions. You can read our report about Lake Vostok drill here.
Sources and more information:
Sampling of lake will provide climate, evolutionary clues British camp deep field, Lake Ellsworth. PHOTO COURTESY BRITISH ANTARCTIC SURVEY. By Summit Voice SUMMIT COUNTY - For many years, scientists have wondered if life in some form has persisted at the very margins of the Earth's enviroment, perhaps tucked two miles deep beneath the surface of...
Mt. Murphy breaks out from the mostly flat, white landscape of West Antarctica. Lakes exist deep below the Antarctic surface because of ice pressure. British researchers are preparing to drill through 3 kilometers (2 miles) of Antarctic ice to search for life in samples from a lake that's been isolated from the outside world for hundreds of...
( via thewatchers.adorraeli.com )
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