Michael Field in Auckland
Agençe France-Presse
Wednesday, 20 August 2003
The cryobot ice submersible, bound for Jupiter's moon, Europa, which scientists would like to test in Lake Vostok (JPL)
Plans to drill into an ancient lake deep under ice in Antarctica may lead it to erupt in a massive geyser-like explosion, scientists have warned.
Lake Vostok in Antarctica has spent 15 million years under 4 km of ice, its waters sealed off from air and light for all that time under the tremendous pressure of the continental ice sheet. The 14,000 km2 lake, about 1,300 km from the South Pole, is one of the world's largest and scientists believe that it could offer unique research opportunities.
But despite opposition from environmentalists who fear drilling into the lake could destroy it, Russian scientists plan to cut through the ice until they come close to the surface of the lake.
U.S. scientists are also interested in drilling into the lake to see if any life forms can exist there, a finding which could lend weight to theories that life exists in other extreme environments such as other planets.
But these projects may be set back by a scientific paper in the latest issue of the journal, Geophysical Research Letters.
Dr Chris McKay at the NASA's Ames Research Centre in California warns that whoever drills into Vostok will have to be extremely careful.
He said the high gas concentrations believed to be present in Vostok "may result in a vigorous gas-driven flow if lake water is brought to the surface. "
He said the concentration of pent-up nitrogen and oxygen in lake water, under a pressure of 2.5 litres per kg, is about equal to that of "an unopened can of Coca Cola".
Burst like a can of soft drink
"The effects of rapid degassing of Coca Cola are well known," McKay said, adding that like the soft drink, the lake can be opened, but very carefully.
"Our research suggests that U.S. and Russian teams studying the lake should be careful when drilling because high gas concentrations could make the water unstable and potentially dangerous," McKay said. Research indicates the oxygen levels in lake water may be 50 times higher than the oxygen levels in ordinary freshwater lakes.
"Lake Vostok is an extreme environment, one that is super-saturated with oxygen," he said. "No other natural lake environment on Earth has this much oxygen."
Research also suggests that organisms living in Lake Vostok may have had to evolve special adaptions, such as high concentrations of protective enzymes, to survive the lake's oxygen-rich environment. Such defence mechanisms may also protect life in Lake Vostok from oxygen radicals, the dangerous by-products of oxygen breakdown that cause cell and DNA damage.
A satellite photo with Lake Vostok highlited
In 1957 the Soviet Union erected its first Antarctic base at Vostok, in part of the territory claimed by Australia. Only in 1994 did they realise they were above a lake equal in area to Lake Ontario, on the border between the U.S. Canada, but up to four times as deep.
The Soviets drilled 3.62 km into the protective shell of ice, but stopped when poised a just few hundred metres above the liquid water. When they pulled out core samples, they filled the hole with kerosene and freon to keep it from collapsing.
Dr David Karl, an oceanographer of the University of Hawaii said the sample, which is still at Vostok, was so clear "you could read a newspaper through this ice core. This is the best sample we have of the open lake, at least until the point the ice is drilled."
Intrusion into unique environment
But some scientists are concerned about intrusions into such a pristine environment. "It doesn't know anything of human beings, fossil fuels or plastics," said Dr Robin Bell, a geophysicist at Columbia University's Lamont-Doherty Earth Observatory, speaking about the lake. "It is a window into life forms and climates of primordial eras."
Environmenatlists have also voiced objections. The Antarctic and Southern Ocean Coalition, a U.S. group based in Washington, called for a moratorium on drilling into Vostok. Any new technology to drill should first be tested on any of the 70 other lakes in Antarctica, they said.
The biggest push to explore the lake comes from the U.S. National Aeronautics and Space Administration (NASA) and the its leading space studies centre, the Jet Propulsion Laboratory in California, both of whom want to study the internal environment of Lake Vostok in preparation for a mission to Jupiter's icy-encrusted moon, Europa.
The New Zealand-based Royal Forest and Bird Society is also opposed to the drilling. "It does seem strange to us that in order to find life on another planet they want to drill into Lake Vostok and contaminate it," the society's Barry Weeber said.
Julie Palais, glaciology program manager for the US National Science Foundation's Office of Polar Programs, said it may take more than a decade for drilling to happen.
"As a scientist you don't want your gravestone to read that this is the person who contaminated one of the last frontiers on the planet," she said.