There Is a Lake the Size of Lake Ontario Buried Under Two Miles of Ice

Lake Vostok sits beneath Vostok Station in East Antarctica, at the cold pole of the planet. Russian and British surveys in the 1970s used radio-echo sounding to map a flat reflector under the ice — the kind of return you get from open water — but the size only became clear after the 1996 RADARSAT-1 satellite imagery and ERS-1 altimetry showed a body of water about 250 by 50 kilometers, an area comparable to Lake Ontario, lying under 3,700 meters of ice.

The lake has probably been sealed from the atmosphere for 15 to 25 million years, since the East Antarctic ice sheet stabilized. The water is liquid because of pressure from the overlying ice and a weak geothermal flux from below. It is supersaturated with oxygen, at concentrations roughly fifty times higher than ordinary surface water — a chemical environment unlike anything else on Earth.

Drilling began in 1989. The Soviet, then Russian, team used a kerosene-Freon drilling fluid to keep the borehole open. Concerns about contamination delayed the final breakthrough for years; the team designed a method in which the lake water, on contact, would push back up the borehole, freeze, and provide a sample. On February 5, 2012, after a quarter-century of work, the drill broke through. Lake water rose 30 to 40 meters into the borehole and froze. The next year's expedition extracted accreted ice and brought it home.

Results from the recovered ice have been controversial. Sergey Bulat's group at the Petersburg Nuclear Physics Institute reported a candidate novel bacterium; other groups argued that almost everything detected was contamination from the drilling fluid. What is in the lake is still substantially unknown. The same is true of the roughly 400 other subglacial lakes mapped beneath the Antarctic ice sheet since.