Satellite composite showing location of Vostok within the Antarctic continent (NASA)

Two and a half miles beneath the surface of Antarctica's central Eastern ice sheet is a body of water 160 miles by 30 miles across known as Lake Vostok, after the Vostok research station above it, built by the former Soviet Union in 1957 and now operated by Russia.

Even by Antarctic standards it's a brutal place, with the dubious honor of holding the record for the lowest measured temperature anywhere on the planet, a mind-if-not-body numbing -129 F or -89 C. Performing any kind of mechanical or scientific work in this environment is an immense challenge.

For the past 14 years a hole has been gradually drilled down from this location into the ancient layers of ice. Each short summer season allowing for a little more progress. Hints that there could be a vast sub-surface body of water arose in the 1950's and 60's. Ground penetrating radar later confirmed these suggestions - and Lake Vostok, with 1,300 cubic miles liquid water, was revealed some 2.5 miles below the ice (although only 500 meters below planetary sea-level).

Radar image of Lake Vostok (Satellite imagery, NASA)

It quickly became clear that this was an environment sealed away from Earth's surface, and although the water in the lake may itself be slowly changed out by the deep ice-dynamics of Antarctica, this process could take well over 10,000 years. It is also possible that hydrostatic sealing has kept the lake truly isolated for millions of years.

So what's happening in Lake Vostok? We don't know. Devoid of light but likely bursting with supersaturated oxygen and other gases, Vostok has long been speculated to be a potential habitat for unique ecosystems of extremophilic microbial life (and who knows what else). Despite the clear risks of contaminating what may be a pristine and fragile environment, Russian scientists have now, after more than a decade, drilled to the top of the lake (see this BBC news item for example, and this report in Nature). Water samples are now going to be extracted by lowering the pressure from the drill rig (and getting, we hope, all the nasty kerosene lubricant and anti-freeze out of the system), and then given full biological and chemical analysis.

It's tremendously exciting just as it's also tremendously worrying that we will have messed up yet another irreplaceable ecosystem. Forward contamination of planets, as I wrote about in my last post, can happen right here under our (frozen) noses. However, if we're lucky then what we'll learn about the lost world of Lake Vostok may provide scientific impetus to get ourselves to one of the extraordinary sub-surface oceans that exist elsewhere in our solar system, from the Jovian moons Europa and Ganymede, to the geyser-spouting mysteries of distant Enceladus. It's possible that what's happening at Vostok Station today is the beginning of our next chapter in the search for life in the universe.

And, an added postscript, an excellent diagram of the vertical/horizontal structure of the lake and its surroundings.