Lake Vostok is a subglacial lake under the East Antarctic Ice Shelf. It is about 500 m below sea-level, but is buried under 4 km of ice. The lake is approximately 250 km long, by 50 km wide and has an average depth of 344 m. Lake Vostok was covered by the ice between 14 and 25 million years ago, when Antarctica was still attached to South America and possibly Australia. The Lake will not have been completely isolated for all of this time; most of the water currently in it is likely to have come from the bottom of the glacial ice-sheet.
Map of Antarctica, showing the location of Lake Vostok. California Academy of Sciences.
A team of Russian scientists and engineers from the Arctic and Antarctic Research Institute has been drilling towards Lake Vostok each short Antarctic summer since 1990 (they were a team of Soviet scientist and engineers when they started out), with an eight year pause from 1998, when the scientists stopped 100 m short of their goal to evaluate how to make the final drill into the lake in a safe and sterile way. They are now expected to make the final breakthrough within the next week; if anything should go wrong and they are unable to complete the drilling process before the end of February, then they will be forced to withdraw for another year. During the Antarctic winter temperatures on the East Antarctic Ice Sheet can fall to -100 °C, conditions which would prevent work by the most hardy of researchers.
A diagrammatic cross section through Lake Vostok, showing the progress of the Russian drill.
While bacteria and other micro-organisms have been recovered from the ice throughout the drilling process, the Russian team have always regarded these as contaminants (some have been described in scientific articles by American researchers). It is thought likely that Lake Vostok will contain an ecosystem that has been isolated from the outside world for tens of millions of years, and that will be rich in extremophilic organisms (organisms that thrive in extreme conditions), an environment that the researchers are keen to avoid contaminating.
The other consideration is safety; Lake Vostok is thought to be very rich in dissolved gasses, to the extent that some researchers believe that an uncontrolled release of pressure might cause up to a quarter of the water in the lake to escape suddenly, like a carbonated drink that has been shaken from a bottle. This would not only probably be fatal to anyone working at the drill-head, it would be likely to cause a permanent change in the climate of Antarctica due to the amount of water vapor released.
The Lake Vostok Drilling Station.
Despite the precautions the Russians are taking, they are still facing criticism from some sources. The Antarctic and Southern Ocean Coalition, an umbrella group representing environmental organizations concerned about the Antarctic is usually supportive of research projects, but has questioned some of the methods used by the Russian group, particularly the use of drill-lubricants and anti-freeze, which could potentially contaminate the lake.
Many scientists regard attempts to drill into subglacial lakes in Antarctica as practice for potential future attempts to look for life elsewhere in the solar system, particularly on the Jovian Moon Europa and Saturn's Moon Enceladus, both of which are thought to have oceans beneath their icy exteriors.