Russian scientists have reached Lake Vostok, a vast body of liquid water hidden roughly 4 kilometers beneath the ice of Antarctica that had been sealed off from the surface for at least 15 million years. The lake is considered one of the most extreme and enigmatic environments on Earth, and researchers have recovered DNA samples from organisms capable of surviving in total darkness there.
Scientific interest in the site grew after a Russian expedition finally reached the lake in February 2012, following decades of work. Gaining access also forced researchers to find ways of collecting samples without introducing foreign substances into an ecosystem whose makeup could show how life survives in total darkness, intense cold, high pressure and scarce nutrients.
A giant lake hidden under four kilometers of ice
Vostok is one of the largest known subglacial lakes on the planet. It stretches about 240 kilometers from north to south and reaches roughly 50 kilometers across at its widest point, according to information from the journal Science. Its surface area is estimated at between 12,500 and 14,000 square kilometers, while its depth reaches several hundred meters and can approach nearly a kilometer in some sections.
How the lake was discovered
The existence of this enormous reserve of water beneath the ice was first proposed in the 1960s, after aerial observations detected an unusually smooth stretch of ice surface. Confirmation came decades later through satellite radar studies. Seismic measurements and ice-penetrating radar allowed scientists to reconstruct the shape of the basin and distinguish its deep and shallow regions.
Earth's heat keeps the water liquid
The presence of liquid water in one of the coldest places on Earth seems contradictory. Surface temperatures near Vostok Station can drop to extreme lows. On 21 July 1983, the station recorded minus 89.2 degrees Celsius, the lowest temperature ever measured on Earth's surface.
Conditions beneath the ice sheet are different, however. Geothermal heat rising from within the planet helps keep the water liquid, while the enormous weight of the ice above alters the freezing point. Estimates cited put the water temperature at around minus 3 degrees Celsius. Observations have also detected tidal effects linked to the gravitational pull of the Moon and the Sun.
Russia's drilling reached the lake in 2012
The Russian project began decades before scientists could even confirm the lake existed. After more than twenty years of drilling, interrupted at various points, the expedition finally reached the water on 5 February 2012, at a depth of about 3,769 meters.
The process raised concerns among scientists. Kerosene and freon were used to keep the borehole open, and any contact between these substances and the lake water risked altering samples and making it harder to identify organisms native to the subglacial environment. When pressure from the lake pushed water up into the borehole and it froze, it formed a natural ice barrier that helped limit the entry of drilling fluids.
Microorganisms in an extreme environment
The possibility of finding life in Vostok made the lake one of the most closely watched targets in Antarctic research. Scientists have analyzed samples of accretion ice, the material that forms when lake water freezes onto the base of the ice sheet. Genetic sequences associated with bacteria, archaea, fungi and other aquatic organisms turned up in those samples.
A study published in 2013 described thousands of species based on DNA and RNA analysis. Rogers, one of the researchers involved, noted that life had shown it could survive in places once thought impossible.
Even so, the findings call for caution. Possible contamination of the samples means scientists cannot say with certainty that every organism identified came directly from the lake water. That uncertainty is part of why Vostok keeps much of its mystery intact, remaining a natural laboratory for studying the limits of life in extreme environments.
