Sub-Surface Life?

This article is taken from the Winter 2011 issue of I, Science magazine

Antonio Torrisi uncovers the secrets held by the mysterious Lake Vostok, Antarctica’s as-yet unexplored sub-surface lake.

The Antarctic is one of the most extreme places on Earth, so it follows it would be one of the least explored. However, remote areas spark scientific and public curiosity, and in 1957 a group of scientists established a research facility, Vostok, in the coldest place on Earth: the East Antarctic Ice Sheet.

Forty years on, scientists confirmed the presence of a long-suspected prehistoric lake 3 miles below the surface. Vostok soon became one of the most-talked-about research facilities in the world, and an international effort was sparked to fund an expedition to the lake. Named Lake Vostok, it is one of the largest lakes on Earth at 15,690 km2; slightly larger than Wales. It remains unique, not only for its great size but also for its huge sub-surface depth. The extreme temperatures, lack of light, and isolation from anything – let alone anything living – present analogies to outer space, and discussions over whether the Lake can sustain life.

Robin Bell and Michael Studinger, of the Lamont Docherty Observatory at Columbia University, understand how vital it is to identify the Lake’s unique geologic structures in order to address the important biological questions that inevitably follow. In 2001, they had a breakthrough in understanding how the Lake may have formed, despite its unusual and inaccessible location. They claim Lake Vostok could be a rift lake, generated by two blocks of Antarctic crust moving apart from one another. Consequently, the high temperatures created by the friction of the moving blocks caused hot springs to form, which then melted the covering ice. The extreme high pressure exerted by the ice sheet keeps the water in a liquid state even though, at -3oC, it should be frozen.

If life has formed from the energy of the hot springs then, since the lake is in complete darkness, it would have been unable to respire through photosynthesis. Scientists think the lake might be up to one million years old and could be supersaturated with nitrogen and oxygen, which are more easily absorbed by water at the extremely high pressures exerted by the 3 miles of overlying ice. Any organisms present here would have evolved in a very different way to us, and only bacteria and micro-organisms are likely to exist.

Russian scientists have been drilling the ice sheet around Vostok station, but have yet to penetrate the lake itself. From analysis of extracted ice-cores they have found three bacteria undoubtedly belonging to the lake surface ice, two of which confirm the theories of Bell and Studinger since they have previously been found in other hot springs in Japan, the US and on the Galapagos islands. Only one type was unclassifiable. In order for further examples of life to be found, researchers need a sample from the Lake itself. This represents a huge technical and scientific issue.

Since the lake has so far remained untouched by humans, any exposure to the atmosphere could contaminate it. Similarly, the kerosene fluid used in the drilling operation to prevent the borehole re-freezing could irreparably pollute the lake, destroying natural habitats and preventing a true scientific investigation. Another risk factor is the possible de-gasification of methane and carbon dioxide, which have accumulated in the Lake and can only be maintained at very high pressures; their release could generate a geyser-like explosion, and destroy any life below.

American and British scientists believe they have found an answer to the dangers of probing. A team of scientists lead by Professor Siegert of the University of Edinburgh will use a new technique to explore another sub-glacial lake. Hot water would be used to excavate down to the lake surface, before carefully inserting a sterilized thermoprobe into the lake and then introducing a submersible hydrobot. This small robot could be guided from the surface to search for bacteria and extract samples of sediments. It would not return to the surface, but instead carry all the instrumentation needed to analyse collected sediments and bacterial life. A masterpiece of engineering and technology, its titanium structure would not degrade and risk contamination of future experiments.

Whilst the exploration of sub-glacial lakes could throw light on the origin of life on Earth, it could also indicate whether or not life could exist on solar system moons such as Europa, which is known to have sub-glacial lakes similar to Vostok. It can give us important insights into our own planet through the decoding of the glacial history of the Antarctic, which, in our current climate crisis, could help study the instability and possible future collapse of the Western Antarctic Ice Sheet.

As stated by the University of California’s Professor Priscu, “Lake Vostok is the holy grail” – and the last crusade has already started.

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