Antarctica – Land of Lakes

Life and ice: How Earth’s subglacial lakes help search for life in space

Despite the harshest conditions at Earth’s poles, life is present even there – on the ice sheet of Antarctica, below it, on the coast and elsewhere, for example. In spite of the extreme climate, living beings are not only the “inhabitants” of research stations. Signs of life are also found under the multi-kilometer layer of ice, in so-called subglacial lakes.

Scientists believe that if there is life in such places, despite the low temperature and high pressure, it may well exist outside the boundaries of planet Earth. The ice seas of Antarctica are seen as potential biotopes for extraterrestrial life.

Unobvious goals of studying subglacial lakes in Antarctica

Years of work by microbiologists and geneticists on subglacial lake samples and specimens have built a methodology for dealing with delicate material and a technology for detecting contaminants. If an interplanetary station ever brings to Earth water from the subglacial ocean of Europa, Ganymede (Jupiter’s satellites) or Enceladus (Saturn’s satellite), the same methods could be used to detect extraterrestrial life.

Scientists believe that the satellite Europa has more water than all the oceans of Earth put together. This water (as well as living organisms, if they exist there) is protected from cosmic radiation and asteroids by a thick layer of ice.

What are subglacial lakes

A subglacial lake, or subglacial lake, is a body of water located under a permanent sheet of ice up to several thousand meters thick. In some cases, such lakes are complete bacterial ecosystems. A large number of subglacial lakes – more than 150 – are just in Antarctica. Scientists suggest that many of them are connected to each other by a system of subglacial rivers, through which the pressure is equalized and water is transported.

About some of Earth’s subglacial lakes

Vostok is the largest subglacial lake in Antarctica. It is under an ice sheet about 4 km thick, which made it unique because it has been isolated from the outside world for several million years. The size of the East is approximately 250×50 km, the area is 15.5 thousand km2 , the depth is more than 1,200 m. In 1989 scientists (joint expedition of the USSR, the USA and France) started drilling the well.

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Due to various aggravating circumstances, the water surface was not reached until 2012. Water, which came to scientists in the form of frozen ice on the drill bit, was subjected to microbiological examination. Scientists were interested in DNA fragments of two types of bacteria. The first turned out to be completely new to science: the DNA of the representative of the species matched the known to science nucleotide sequences only by 86%. The second was a relative of the bacteria from the Greenland glacier. Later, a third species, bacillus, was discovered. It is of interest because bacilli are heterotrophic organisms, that is, they feed on organics, which are almost absent in the lake water.

Willans is a subglacial lake, which is located at a depth of about 800 m. Its own depth is 1. 5-2 m, and its area is 60 km 2 . In 2013, American scientists reached the surface of the lake and discovered living organisms, chemotrophs, which obtain energy by oxidizing ammonium and methane, which probably rise from the bottom of the lake.

Mercer, an ice-covered lake 1,067 m thick in Antarctica, has an area of 160 km 2 and a depth of 10-15 m. Because of global warming, Lake Mercer has been identified as a high risk site for ice sheet collapse. American scientists reached the lake’s surface in 2018 and studied water samples. It turned out to contain enough oxygen to support aquatic animals, and the bacterial density here is at least 10,000 per milliliter.

SALSA (Subglacial Antarctic Lakes Scientific Access) Expedition at Lake Mercer

Elsuerth – subglacial lake of Antarctica, which, according to scientists, had no connection with the outside world for about 125 thousand years. It is located under an ice sheet 3 km deep and has the following parameters: size – 14.7×3.1 km, area – 28.9 km 2 , volume – 1.37 km 2 and a depth of 156 m. Scientists in Great Britain have been studying the lake since 1996. In 2012, scientists were able to get close to the surface of the water, but for technical reasons the water samples were not examined.

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Life Beyond Earth – Scientists’ Predictions

In recent news, scientists have discovered methane on Saturn’s satellite, Enceladus. This could be a sign of life or evidence of a chemical process as yet unknown to science. Perhaps at the bottom of the ocean on Enceladus there are hydrothermal springs similar to those on Earth. On Earth, such springs are surrounded by microbes that consume dihydrogen and carbon dioxide and produce methane. According to a published study, the ocean on Enceladus is about a billion years old.

Ganymede, Jupiter’s satellite, is also of interest to scientists because there is speculation that this celestial body has several layers of ocean separated by different types of ice, formed at different depths and under different pressures. If these assumptions hold true, there could be different life in each of the layers, adapted to the specific conditions of its layer. In 2022, the interplanetary station JUICE (JUpiter ICy moons Explorer) of the European Space Agency is to go to Ganymede.

To study the subglacial water on Europa (and the thickness of the ice shell according to scientists ranging from 2 to 30 km) proposed to send a tunnel robot to the surface of the satellite with a nuclear reactor, which could drill the ice, while collecting samples of ice and water and sending information to the surface through a fiber-optic cable. NASA is funding this project. Read a detailed article about Europe here.

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