Lake Vostok (Russian: озеро Восток, romanized: ozero Vostok) is the largest of Antarctica's 675 known subglacial lakes and the 16th largest lake in the world by area. It is located at the southern Pole of Cold, beneath Russia's Vostok Station, under the surface of the central East Antarctic Ice Sheet, which is 3,488 meters (11,444 feet) above mean sea level. The surface of this freshwater lake is approximately 4,000 meters (13,100 feet) below the ice, placing it at about 500 meters (1,600 feet) below sea level.
The lake is named after the Vostok Station, which takes its name from Vostok (Восток), meaning "East" in Russian. The lake is located in East Antarctica. The existence of a subglacial lake was first suggested by Russian geographer Andrey Kapitsa based on seismic soundings made during the Soviet Antarctic Expeditions in 1959 and 1964 to measure ice thickness. Continued research by Russian and British scientists confirmed the lake's existence in 1993 using ERS-1 laser altimetry by J. P. Ridley.
The ice above Lake Vostok contains a continuous record of past climate conditions spanning 400,000 years. However, the lake water itself may have been isolated for 15 to 25 million years. Because Lake Vostok may contain an environment sealed below the ice for millions of years, the conditions could resemble those of ice-covered oceans thought to exist on Jupiter's moon Europa and Saturn's moon Enceladus.
On February 5, 2012, Russian scientists completed the longest ice core ever drilled, reaching 3,768 meters (12,400 feet) and piercing the ice to the lake's surface. The first sample of freshly frozen lake ice was collected on January 10, 2013, at a depth of 3,406 meters (11,175 feet). However, water from the lake immediately flowed up the borehole, mixing with Freon and kerosene used to prevent freezing. Scientists believe the lake's liquid layer may contain unusual forms of life or a fossil water reserve. Some environmental groups and scientists have opposed the drilling project, arguing that hot-water drilling would have less environmental impact.
Discovery
Russian scientist Peter Kropotkin first suggested the possibility of fresh water beneath Antarctic ice sheets at the end of the 19th century. He believed that the immense weight of thousands of meters of ice pressing down on the ice sheet could lower the melting point of the ice at its bottom, turning it into liquid water. Kropotkin’s idea was later expanded by Russian glaciologist Igor Zotikov, who studied it in his PhD thesis in 1967.
Russian geographer Andrey Kapitsa used seismic soundings in the area of Vostok Station during Soviet Antarctic Expeditions in 1959 and 1964 to measure the thickness of the ice. In the mid-1990s, Kapitsa joined a meeting about Antarctica in Cambridge and realized that data from his earlier research showed signs of water beneath the ice. Further studies by Russian and British scientists confirmed the lake’s existence in 1993 using ERS-1 laser altimetry.
In the early 1970s, British scientists used airborne radar to scan Antarctica and found unusual readings that suggested a freshwater lake was hidden under the ice. In 1991, J. P. Ridley, a scientist from the Mullard Space Science Laboratory, directed the ERS-1 satellite to send high-frequency signals toward the center of Antarctica. The satellite’s data supported the earlier radar findings, but these results were not published in the Journal of Glaciology until 1993. Space-based radar showed that this lake is one of the largest in the world and one of about 140 subglacial lakes in Antarctica. Scientists mapped the lake by combining data from airborne radar and satellite measurements. The discovery was published in the journal Nature on June 20, 1996. The lake is covered by more than 3 kilometers of ice and contains at least 22 pockets of liquid water, each about 10 kilometers long.
The lake is named after Vostok, a ship used by Russian explorer Admiral Fabian von Bellingshausen during the discovery of Antarctica. In Russian, "Vostok" means "East," so the name reflects the lake’s location in East Antarctica.
In 2005, an island was discovered in the center of the lake. In January 2006, scientists found two smaller lakes nearby and named them 90 Degrees East and Sovetskaya. Researchers believe these lakes may be connected by a network of underground rivers. Scientists from the Centre for Polar Observation & Modelling suggest that many subglacial lakes in Antarctica may be temporarily linked. Changes in water pressure could cause sudden rivers to form, moving large amounts of water through the ice.
Geological history
Africa separated from Antarctica about 160 million years ago, and the Indian subcontinent followed around 125 million years ago during the early Cretaceous period. Approximately 66 million years ago, Antarctica (which was still connected to Australia) had a warm climate with tropical to subtropical conditions, including marsupial animals and large temperate rainforests.
Lake Vostok is a small geological area, about 50 kilometers wide (about 31 miles), located within a much larger region where the Gamburtsev Mountain Range, a mountain range under the ice, and the Dome C area collided. The lake is covered by layers of sediment 70 meters thick (about 230 feet), which may hold important information about Antarctica’s climate and life before the ice cap formed.
Traits
Lake Vostok's water is believed to have been trapped under thick ice about 15 million years ago. Early studies suggested the lake's water had remained unchanged for about one million years. Later research by Robin Bell and Michael Studinger from the Lamont–Doherty Earth Observatory of Columbia University showed that the lake's water freezes and moves with the Antarctic ice sheet, while new water from other parts of the ice sheet replaces it under high pressure. This process results in the entire lake's water being replaced every 13,300 years, which is its average residence time.
The lowest natural temperature ever recorded on Earth, −89 °C (−128 °F), was measured at Vostok Station on July 21, 1983. The lake's average water temperature is about −3 °C (27 °F). The water stays liquid below the normal freezing point because of the high pressure from the ice above. Heat from Earth's interior may warm the lake's bottom.
Lake Vostok is an environment with very few nutrients. It contains much more nitrogen and oxygen than typical freshwater lakes, with 2.5 liters (0.088 cubic feet) of these gases per 1 kilogram (2.2 pounds) of water—50 times more than usual. The immense pressure from the ice above, estimated at 345 bars (5,000 psi), contributes to the high gas levels.
Oxygen and other gases dissolve in the lake's water or are trapped in structures called clathrates. Clathrates form when gases are enclosed in ice-like cages, resembling packed snow. These structures form at the lake's deep, high-pressure areas and would become unstable if brought to the surface.
In April 2005, researchers from Germany, Russia, and Japan discovered that Lake Vostok experiences tides. The lake's surface rises about 12 millimeters (0.47 inches) depending on the positions of the Sun and Moon. The lake is in complete darkness, under 355 bar (5,150 psi) of pressure, and is expected to have high oxygen levels. This has led to speculation that any life in the lake might have evolved uniquely in this environment. A 1 microtesla magnetic anomaly, covering an area of 105 by 75 kilometers (65 by 47 miles), is located on the lake's eastern coast. Scientists think this anomaly might be caused by thinning of Earth's crust in that area.
Living Hydrogenophilus thermoluteolus microorganisms have been found in ice cores drilled from Lake Vostok. These microbes live on the surface and suggest the possibility of a deep biosphere using heat from Earth's crust around the lake. Scientists believe microbial life might exist in the lake despite the extreme cold, high pressure, low nutrients, high oxygen levels, and lack of sunlight. Jupiter's moon Europa and Saturn's moon Enceladus are also thought to have lakes or oceans beneath thick ice. Finding life in Lake Vostok could support the idea that life might exist on these icy moons.
Lake Vostok is 250 kilometers (160 miles) long and 50 kilometers (30 miles) wide at its widest point. It covers an area of 12,500 square kilometers (4,830 square miles), making it the 16th largest lake by surface area. With an average depth of 432 meters (1,417 feet), it has an estimated volume of 5,400 cubic kilometers (1,300 cubic miles), making it the 6th largest lake by volume.
Research
In 1998, scientists at Vostok Station drilled one of the longest ice cores in the world. A team from Russia, France, and the United States worked together to drill and study the core, which was 3,623 meters (11,886 feet) long. Ice samples from near the top of the lake were found to be as old as 420,000 years. Scientists believe the lake has been isolated from the surface since the ice sheet formed 15 million years ago. Drilling stopped about 100 meters (300 feet) above the suspected boundary between the ice sheet and the lake to avoid polluting the lake with Freon and kerosene used to keep the borehole open.
From the ice core, scientists discovered microbes that may have come from the lake water freezing onto the bottom of the ice sheet. This suggests the lake water might support life. Researchers think the lake could have a unique environment for ancient bacteria with genes that developed over 500,000 years.
In January 2011, the head of the Russian Antarctic Expedition, Valery Lukin, said his team had only 50 meters (200 feet) of ice left to reach the lake. They switched to a new drill using clean silicone oil to avoid contamination. Instead of drilling all the way into the lake, they planned to stop when the drill detected water. At that point, the drill would be removed, and water would be left to freeze, creating an ice plug at the bottom of the hole. Drilling stopped on February 5, 2011, at a depth of 3,720 meters (12,200 feet) to allow the team to leave before the Antarctic winter. The team left by aircraft on February 6, 2011.
The team planned to return the following summer to take a sample of the ice and study it. In January 2012, Russian scientists drilled again and reached the surface of the lake on February 6, 2012.
In 1999, scientists first found evidence of microbes in the ice that forms when lake water freezes onto the bottom of the ice sheet. Later, a team led by Scott O. Rogers studied bacteria and fungi from ice collected during U.S. drilling projects in the 1990s. These findings suggest the lake is not lifeless but has a unique ecosystem. In 2013, Rogers’ team studied DNA and RNA in the ice and found 3,507 unique gene sequences. About 94% of the sequences were from bacteria, and 6% were from Eukarya. Many of the organisms found were similar to those in lakes, oceans, soil, and other environments. Sequences from aerobic, anaerobic, and other types of organisms were present, including some from multicellular eukaryotes. The study also found bacteria that live in fish intestines.
Some scientists, like David Pearce and Sergey Bulat, questioned whether the DNA found in the ice was from the lake or from contamination during drilling. The ice cores drilled in the 1990s were not sterilized, as they were used to study past climates, not life. Scott Rogers disagreed, arguing the samples were not heavily contaminated.
In 2020, Colby Gura and Scott Rogers studied ice from Lake Vostok and found that the ice at the bottom of the lake had a completely different group of organisms compared to the ice formed from lake water freezing. This suggests two separate ecosystems. The study also found bacteria that live in fish intestines and a molecular sequence similar to a type of Antarctic fish that produces antifreeze proteins.
In 2013, Russian scientists studied water samples from Lake Vostok and identified 255 contaminant species. They also found an unknown bacterium not found in any international databases. However, a scientist from the same team suggested the bacterium might use kerosene, a drilling chemical, as an energy source.
In January 2015, Russian scientists used a new "clean" drill to collect water from Lake Vostok without antifreeze contamination. However, the drilling technology did not work well, and the water rose more than 500 meters in the borehole. The project was paused due to lack of funding.
In 2019, the Russian government ordered the construction of a new wintering complex at Vostok Station, partly funded by a billionaire. The complex can support 35 people in the summer and 15 in the winter, with four diesel generators. The complex was delivered in 2021 and will be installed over four years.
Some scientists and environmental groups have opposed the drilling project, arguing that hot-water drilling might cause less harm to the lake. They are concerned that antifreeze chemicals could contaminate the lake. Scientists from the U.S. National Research Council say it should be assumed that life exists in Lake Vostok and that strict measures are needed to protect it from contamination.
The original Russian drilling method used Freon and kerosene to keep the borehole open. About 54 tons of these chemicals have been used above Lake Vostok. Other countries, such as the United States and Britain, have not yet successfully drilled into the lake.