Imagine drilling through ice for 23 years to reach a lake nobody had ever seen, in the coldest place on Earth, in a research station that holds the world record for the lowest temperature ever recorded — and then, on the day you finally break through, having the lake itself shoot up the borehole to meet you. On the afternoon of 5 February 2012, at Russia’s Vostok Station on the East Antarctic ice sheet, that is approximately what happened. The drill bit, after 23 years of intermittent operation in the most punishing field conditions on the planet, finally penetrated the last few centimetres of ice and entered the surface of Lake Vostok at a depth of 3,769 metres — about 12,366 feet, or roughly 2.4 miles. The lake water beneath, compressed by the weight of nearly four kilometres of overlying ice, was under enormous hydrostatic pressure. The moment the drill broke through, the lake water surged upward into the borehole. It rose approximately 30 to 40 metres before encountering ice cold enough to freeze it solid. The plug of frozen lake water then sealed the borehole from below, in a kind of self-cleaning closure that the Russian team had specifically anticipated and designed the drill operation to produce.
As per Science magazine’s coverage of the breakthrough, citing Valery Lukin, leader of the Russian expedition, the team had been working toward this specific moment since 1989, when the Soviet (and later Russian) Antarctic programme first began deep ice-core drilling at the Vostok site. The original purpose of the drilling was paleoclimate research — recovering ice cores that contained trapped air bubbles from earlier periods of Earth’s history, which could be analysed to reconstruct atmospheric composition going back hundreds of thousands of years. The existence of Lake Vostok beneath the Vostok Station was not known when drilling began. The lake’s existence was inferred indirectly in the 1960s from aerial photography showing an unusually flat patch of ice surface, and was confirmed in 1993 through satellite radar surveys that could penetrate the ice and detect the liquid water beneath. By that point, the deep drilling at Vostok was already well underway, and the project’s scientific purpose shifted to include the eventual penetration of the lake itself.
The lake beneath
Lake Vostok is approximately 250 kilometres long and 50 kilometres wide — about 150 miles by 30 miles — which makes it slightly smaller than Lake Ontario but comparable in scale, and the largest of approximately 400 subglacial lakes that have now been mapped beneath the Antarctic ice sheet. The water in the lake is liquid, despite the surrounding air temperatures at the surface of the ice sheet routinely dropping below minus 80 degrees Celsius. Several factors keep it from freezing. The weight of the overlying ice raises the lake’s pressure to approximately 350 atmospheres, which lowers the freezing point of water by several degrees. Geothermal heat from the Earth’s interior keeps the lake bottom warmer than the ice above. And the ice itself functions as an insulator, isolating the lake’s interior from the extreme cold of the polar atmosphere.
The duration of the lake’s isolation is one of the more remarkable features of the discovery. According to TIME magazine’s coverage of the breakthrough, Lake Vostok has been sealed beneath continuous Antarctic ice for somewhere between 15 and 34 million years, with most estimates clustering toward the upper end of that range. Whatever microbial communities, dissolved organic chemistry, and physical conditions are present in the lake today have evolved or accumulated essentially independently of the surface biosphere across that entire period. The lake’s interior is one of the few isolated environments on Earth that has been disconnected from the surface for geological rather than merely historical timescales. The biological implications are substantial: if there is life in Lake Vostok, it is life that has been evolving along its own trajectory for tens of millions of years, in conditions of total darkness, high pressure, near-freezing temperatures, and limited nutrient input.
Why the breakthrough mattered
The scientific interest in Lake Vostok extends well beyond its identity as a curiosity of Antarctic geology. The lake is widely considered to be the best available terrestrial analogue for the kind of subsurface liquid water environments that may exist on other worlds in the solar system. Jupiter’s moon Europa is believed to contain a global ocean of liquid water beneath an outer ice crust, kept liquid by tidal heating from Jupiter’s gravitational pull. Saturn’s moon Enceladus has a similar configuration, with confirmed plumes of liquid water erupting through its icy surface. According to NBC News’s coverage of the Russian breakthrough, including comment from NASA’s then-chief-scientist Waleed Abdalati, the techniques developed to access and analyse Lake Vostok have direct relevance to the eventual missions that will attempt to sample the subsurface oceans of these other worlds. The technical, biological, and contamination-management challenges of drilling into a 15-million-year-isolated lake on Earth are, in important ways, simpler versions of the challenges that will face any spacecraft attempting to sample Europa or Enceladus.
The contamination management was, in fact, the most delicate aspect of the 2012 breakthrough. The Russian team had to use approximately 60 tonnes of kerosene and Freon in the borehole during the drilling, both as anti-freeze and as a means of equalising pressure with the surrounding ice. The drilling chemicals are not the kind of substances anyone wants introduced into a pristine 15-million-year-isolated lake. The pressure-driven upward surge of lake water at the moment of breakthrough was specifically engineered into the drill design to address this problem: when the lake water rose and froze in the borehole, it formed a plug that prevented the drilling chemicals from flowing downward into the lake. The team then withdrew from Vostok Station shortly after the breakthrough, leaving the plug of frozen lake water in place until the following Antarctic summer.
The samples and what they showed
According to Columbia Climate School’s coverage of the 2012 breakthrough and its scientific aftermath, the Russian team returned to Vostok in December 2012 to retrieve the frozen plug of lake water that had filled the borehole. The plug was extracted, transported to Russia, and analysed in laboratories in St. Petersburg over the following months. Initial analyses reported DNA traces from more than 3,500 distinct organisms — primarily bacteria and fungi, including some unfamiliar species — but the interpretation of these findings was contested in subsequent papers, partly because of the inherent difficulty of distinguishing genuine Lake Vostok organisms from contamination introduced by the drilling chemicals, the borehole environment, and the sample handling. The methodological challenges of confirming an isolated ancient ecosystem from a single contaminated sample are substantial, and the field is still working to resolve them.
Subsequent drilling campaigns at Vostok and at other Antarctic subglacial lakes have continued to refine the techniques. A 2013 American expedition to Lake Whillans, a smaller subglacial lake under a different part of the Antarctic ice sheet, used a “hot-water” drilling technique that introduced less chemical contamination and recovered cleaner samples; the Lake Whillans samples confirmed the presence of active microbial communities in subglacial environments, providing independent support for the basic biological finding from Vostok. A British expedition to Lake Ellsworth in late 2012 was forced to abandon its drilling effort after technical problems, but planning for future Antarctic subglacial lake missions continues. The 400 known subglacial lakes beneath the Antarctic ice sheet now represent one of the more active frontiers in terrestrial exploration — a sealed-off network of liquid water environments, accessible only through engineering feats comparable in difficulty to the early space missions, sitting beneath the most physically remote landmass on Earth. Lake Vostok was the first to be reached, in February 2012, by a Russian drill that had been working its way downward through the ice for 23 years before the lake came up the borehole to meet it.
