Lake Vostok

Lake Vostok is a massive body of fresh water hidden beneath the East Antarctic Ice Sheet. It is the largest of the 675 known subglacial lakes in Antarctica. By surface area, it ranks as the 16th largest lake on Earth. The lake is located near the southern Pole of Cold, underneath the Russian Vostok Station.

This station and the lake share a name derived from the Vostok, a sloop-of-war. In Russian, Vostok means "East," which correctly identifies the lake's location in East Antarctica.

Maintaining liquid water under kilometers of ice requires specific physical conditions. The immense weight of the overlying ice creates extreme pressure. This high pressure lowers the melting point of the water. Because of this, the lake stays liquid at approximately -3 degrees Celsius.

Geothermal heat from the Earth's interior may also warm the bottom of the lake. This combination of pressure and heat allows a liquid environment to exist in a frozen continent.

Scientists have used many different methods to study this hidden environment. In the late 19th century, Peter Kropotkin first theorized that ice pressure could create liquid water. Later, Russian geographer Andrey Kapitsa used seismic soundings during expeditions in 1959 and 1964. These soundings helped measure the thickness of the ice sheet. In 1991, J. P. Ridley used ERS-1 satellite laser altimetry to confirm the lake's presence.

These findings were finally published in the journal Nature on June 20, 1996.

The lake is a complex system with several distinct features. It contains at least 22 cavities of liquid water, which average 15 kilometers in diameter. In 2005, researchers discovered an island in the central part of the lake. They also found two smaller nearby lakes named 90 Degrees East and Sovetskaya in 2006.

Glaciologists believe these subglacial lakes might be connected by a network of underground rivers. These rivers may form suddenly due to varying water pressure.

Lake Vostok is an oligotrophic extreme environment, meaning it has very low nutrient levels. Despite this, it is expected to be supersaturated with gases. The levels of nitrogen and oxygen are 50 times higher than in ordinary surface lakes.

These gases are often trapped in clathrates, which are icy, snow-like structures. These structures form under high pressure and become unstable if brought to the surface. The lake also experiences tides, with the surface rising about 1 meter depending on the Sun and Moon.

Researchers study the lake by drilling long ice cores. These cores provide a paleoclimatic record spanning 400,000 years. On February 5, 2012, a Russian team completed the longest ice core ever made. They successfully pierced the ice shield to reach the lake's surface.

However, the process is difficult. When the ice was pierced, lake water gushed up the borehole. This water mixed with the Freon and kerosene used to keep the hole from freezing.

The study of Lake Vostok has major implications for space exploration. The environment resembles the ice-covered oceans hypothesized to exist on Jupiter's moon Europa. It also shares similarities with Saturn's moon Enceladus.

If microbial life exists in this dark, high-pressure environment, it could prove life can survive on icy moons. Scientists have already found extremophile microbes in deep ice cores near the lake. This suggests a deep biosphere may exist using geothermal systems in the bedrock.