Wednesday, June 20, 2007

Piercing the mysteries of Lake Vostok

The Russian scientific base Vostok lies almost directly above an immense sub-glacial lake, Lake Vostok. The lake, which is hidden under more than 3km of ice, is the size of Corsica.

Lake Vostok is as yet untouched. Scientific pressure to directly sample the lake's water is strong. However it is currently counterbalanced by concerns about contaminating the lake by external life-forms transported by the sampling equipment.

How long this balancing act will continue is unknown. Le Figaro published an article yesterday, Antarctique : la Russie veut percer les mystères du lac Vostok, on Russia's intention to pierce through to the lake next year.

The Russian plan involves extending the current Vostok ice-core drill shaft, which currently stops 90 m above the lake surface, by another 70 m, until it reaches 20 m above the water. The second step will be to continue drilling with a small diameter thermal probe which will reach the lake itself. Lake water will then rise up the drill hole, where it will freeze. The then frozen lake water will be extracted by drilling this new ice-core.

There may be other ways to sample frozen water from Lake Vostok. Researchers from the Lamont-Doherty Earth Observatory at Columbia University believe that the surface of the lake naturally freezes onto the bottom of the ice-cap, and is dragged along with the ice as it descends slowly towards the Antarctic ocean.

The Columbia researchers suggest the entire volume of the lake is removed every 13,000 years. They have put together this very clear Lake Vostok water animation explaining their findings. The source of the replacement water remains a mystery, but it may have something to do with the interconnectedness of the sub-glacial Antarctic lakes.

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