On January 28, 1820, the polar expedition leaded by Fadei Bellingshausen and Mikhail Lazarev on the wooden sloops Vostok and Mirny reached the shores of the Southern Land. Until that moment, Antarctica remained the last uncharted waters on our planet, and many contemporaries did not even believe in the existence of solid earth at these latitudes. It is interesting that British maps of the end of the 18th century depicted only the boundless ocean there. However, despite the success of the Russian Antarctic expedition, the first human set his foot on the continent only 80 years later.
200 years of great discoveries — from the expeditions of the “heroic century” up to the present day
The matter is that Antarctica is the most hostile continent for humans, due to its natural conditions. It is distinguished by an extremely harsh climate — average daily temperatures in winter go down to -60 °C — -75 °C, and in summer — -30 °C — -50 °C. In 2010, as a result of the analysis of satellite data, NASA recorded the lowest air temperature on Earth in the entire history of observations — -93.2 °C. In addition, Antarctica is the highest continent — its height is 2000 m above sea level, while the thickness of the ice cover is 3-4 km. Polar explorers who work at stations located deep in the continent face essentially the same conditions as high-altitude climbers — thin air, extremely low temperatures, a lack of oxygen, high levels of solar radiation, and strong cold winds.
The first Antarctic polar station in history was established in 1898 on the shores of Cape Adare by the British Antarctic Expedition led by the Norwegian explorer Carsten Borchgrevink . It is interesting that this hut has been well preserved to this day and is accessible for tourists.
The first stone structure in Antarctica was built on Laurie Island by the Scottish National Antarctic Expedition led by William Speirs Bruce in 1903. Six polar explorers could live and work in this building all year round. Later, in 1906, the British handed it over to Argentina for permanent use. Since then, this station, named Orcadas, is officially the oldest one and operates continuously.
In 1943-1945, during the British expedition, three polar stations were established: on Deception Island (1943), on the coast of Graham Land (1944) and on the shore of Hope Bay (1945). They became the first stationary bases built on the Antarctic continent. After the end of the Second World War, a powerful wave of research into the southern continent by various countries began. In 1947-1948, the Chilean Antarctic stations Arturo Prat and General-Bernardo-O’Higgins were founded, in 1954 — the Australian Mawson, in 1956 — the French Dumont d’Urville, the American McMurdo, and the Soviet — Mirny. In 1996, with the assistance of the British Antarctic Survey (which sold its Faraday station for a symbolic price of one pound), Ukraine joined the ranks of countries that have their own station on the southern continent. It was named Academician Vernadsky commemorating the first president of the Academy of Sciences of Ukraine.
Currently, Antarctica holds almost 50 permanent and 40 seasonal polar stations belonging to 27 countries. From 1 to 4 thousand people inhabit them during the year. Scientists tirelessly conduct geological-geophysical, paleontological, meteorological, oceanographic and medical-biological research.
Flora and fauna of Antarctica tens of millions of years ago — impressive paleoreconstructions
The natural world of Antarctica nowadays stands out for its originality and uniqueness. The Antarctic icefish Champsocephalus gunnari, which was discovered in 1928 by the biologist Dietlef Rusted, who called it the “white crocodile fish”, deserves special attention. It has large eyes, a voluminous mouth full of teeth, and transparent fins that resemble long feathers. The color of the fish is very pale, and some parts of its body are completely transparent. The gills are also unusual — they are white and resemble yogurt in consistency.
The icefish is also unique in that its body does not produce hemoglobin and red blood cells at all, which is why its blood is not red, but translucent white. Ice crystals form in the blood of this amazing creature, which would be fatal to many other species. The fact is that Champsocephalus gunnari is able to produce a special antifreeze protein, which prevents the already formed icicles from becoming the centers of crystallization, which would lead to the complete freezing of the fish. Blood and intercellular fluid remain liquid. It is this feature that allowed the icefish to adapt to the harsh conditions of the Antarctic Ocean, which washes the Antarctica — where the water temperature is approximately +1.5 °C in summer and -1.8 °C in winter (as you know, ocean water freezes at temperatures below zero). Icefish can freeze completely only at a temperature of -6 °C. It is a vivid example of how a living nature can successfully adapt to extreme environmental conditions.
It is worth mentioning that during the long history of life on Earth, which is almost 4.5 billion years, Antarctica has not always been a harsh cold continent. More than 170 million years ago, it was part of the supercontinent Gondwana, and it became an independent continent with modern outlines only about 25 million years ago.
Paleontological findings allow us to get an idea of the fauna of Antarctica during the early Jurassic period (194–188 million years ago). So, in 1991, the American geologist David Elliott, during excavations on Mount Kirkpatrick near the Beardmore Glacier, found the fossilized remains of a previously unknown species of dinosaur — Cryolophosaurus, which was distinguished by a unique transverse crest, because of which it was unofficially called Elvisosaurus hinting of Elvis Presley’s hairstyle. The fossils were officially described in 1994. According to experts, the length of the ancient lizard was 6-8 m, and the weight could reach 900 kg. Later, the remains of large prosauropods, as well as pterosaurs and synapsid tritylodonts were also found at the excavation site.
In 2012, specialists working under the auspices of the Joint Program for the Study of the World Ocean were able to get literally “to the bottom” of the Eocene period (55 million years ago) by drilling in the Wilkes Land shelf zone on the east coast of Antarctica. The machine drilled one kilometer of sedimentary rocks, thanks to which it was possible to raise a sample to the surface, where they found pollen and spores of plants (related to modern baobab and macadamia), as well as the remains of single-celled organisms, which helped to form an idea of the nature on the mainland at that time.
According to scientists, the territory of modern Antarctica was located much further north at that time, much closer to subequatorial latitudes, and was characterized by a subtropical climate. In winter, the temperature was almost 10 °C, and in summer it could rise to 25 °C. It is worth noting that at that time the average temperature on the entire the Earth was 5 degrees higher than it is now. Nor was there such a sharp distinction between the equator and the poles. This climatic period is considered the warmest on Earth in the last 65 million years. At the same time, the concentration of carbon dioxide in the atmosphere was more than twice the current level. Antarctica was completely forested and inhabited by a variety of ancient life forms (including the first modern mammals), with palm trees growing in the coastal parts of the continent, and conifers (araucaria) and beech trees nearer the pole.
Research of the deep subglacial lakes of Antarctica is a scientific challenge of the 21st century
The end of the 90s of the XX — zero years of the XXI century were marked by amazing discoveries in Antarctica. First, Russian scientists at the Vostok polar station found an ice-covered lake that does not freeze — the largest of the Antarctic lakes discovered to date, which contains approximately 5,400 km3 of water. This is only 3.5 times less than in Baikal, the largest freshwater reservoir on our planet. Vostok lake is located under an ice sheet 4 km thick. It is really unique due to the fact that, according to scientists, it was isolated from the Earth’s surface for several million years.
In 2006, American geophysicists Robin Bell and Michael Studinger announced the discovery of the second and third largest subglacial lakes with an area of 2,000 km2 and 1,600 km2, located at a depth of almost 3 km below the surface of the continent. To date, approximately one and a half hundred such objects have already been discovered in Antarctica. These deep subglacial lakes have aroused considerable interest in the scientific community. Microbiologists have suggested that living organisms can live in such reservoirs, since all the necessary factors exist there.
Recently, scientists from the Michigan Technological University collected water samples from the subglacial Lake Willans, which is located in West Antarctica and lies at a depth of almost 800 meters below the surface. The study allowed us to learn more about the conditions to which microbial life can adapt. It is known that the key element of nutrition for microorganisms is organic carbon.
The researchers’ calculations showed that the subglacial lakes contain 50-55 times more carbon than the minimum amount needed to support microbial life. Other favorable factors are a sufficiently high water temperature (3°C at the water-ice interface and up to 10°C at depth), as well as high oxygen content (approximately 50 times higher than in normal fresh water). Researchers assume that the water of the lakes is enriched with oxygen getting it from the upper layers of ice, which gradually sink to the depths, and the heat is generated by underground geothermal sources. The temperature of the near-surface layer of lake ice does not exceed -7°С, which is the lower limit for the metabolic activity of bacteria known to science. According to calculations, the pressure of water in the lake is more than 300 atmospheres, but microorganisms could well adapt to such conditions. Adapting, they can have unique properties, because they were isolated from the rest of the biosphere for a very long period, so evolutionary processes took place there independently. Scientists believe that the study of such closed ecosystems will allow to expand knowledge not only about the Earth, but can also serve as a key to understanding the possibility of the existence of life on other objects of the Solar System, having conditions similar to the Antarctic.
As early as 1989, joint efforts of Soviet, French and American researchers began to develop the 5G-1 deep well above Vostok Lake, located near the magnetic pole of Antarctica. For millions of years, the reservoir was isolated from the outside world and lived its reclusive life. In 2015, Russian polar explorers managed to completely drill through the ice layer above the lake and reach its surface at the mark of 3769.3 meters, raising two ice samples to the ground. At a depth of more than two kilometers, microorganisms were found in the samples. A bacterium called w123-10 was found in the water frozen on the drill string. In early October 2016, information was made public about the uniqueness of the found microorganism — the bacterium has 86% genetic similarity to living creatures known to modern science.
The organism w123-10 became the second bacterium found during the drilling of Vostok Lake. The first was discovered in 2004 by Russian and French scientists, who at depths of 3,607 and 3,561 meters found signs of the thermophilic beta-proteobacterium Hydrogenophilaceae thermoluteolus, which can survive at temperatures of -500C. The discovery of this bacterium led to a revision of generally accepted modern tectonic models of Antarctica and became evidence of the presence of geothermal sources in its subglacial lakes. Available data indicate that the most likely candidates for life in a glaciated lake are chemoautotrophic bacteria — in particular, methanogenic archaebacteria and sulfate-reducing bacteria. Such creatures would be able to survive in complete darkness and with an excess of oxygen. However, scientists have so far studied only the ice of the first type, while active life in Vostok Lake, if it really exists, most likely is found closer to its bottom, which researchers have not yet reached.
If there really is life in the frozen Vostok Lake, it is probably arranged in an extremely unique way. Astrobiologists believe that similar conditions for potential organisms exist in the icy oceans of the moons of Jupiter (Ganymede, Callisto and Europa), Saturn (Dione and Enceladus), as well as at the poles of Mars. Thus, the study of frozen Antarctic lakes allows us, here on Earth, to learn a lot about potential life in the cold worlds of the Solar System.
The search for extraterrestrial life outside the terrestrial-type planets. Ambitious plans for the coming years
Since Jupiter is closer to the Earth than Saturn, recently the attention of scientists has been focused on the detailed study of its moons, especially Europa (another name is Jupiter II). This small cosmic object (smaller than the Moon) was first discovered in 1610 by Galileo Galilei using a telescope. Since the end of the last century, active observations of Europa have been carried out using space devices.
To date, we know that the mass of Europa is greater than that of all known satellites of the Solar System (average density is 3.013 g/cm3), which indicates that it consists mainly of silicate rocks, with an iron core in the center. Thus, by its composition, Europa is similar to the planets of the terrestrial group. It is characterized by an extremely rarefied atmosphere, which consists mostly of oxygen. The satellite’s surface consists of ice 80 to 170 kilometers thick and is one of the smoothest in the Solar System. There is a scientific hypothesis according to which a subglacial salty ocean is located under the ice of Europe. According to scientists’ calculations, its volume can be 3⋅1018 m3, which is twice the volume of the Earth’s world ocean.
In support of this hypothesis, the results obtained in 2019 by American astronomers using the Hubble telescope and the STIS spectrometer installed on it are cited. It turned out that the surface of Europa is covered with a layer of sodium chloride (or ordinary table salt), which was exposed to cosmic radiation, which is why the satellite has such an unusual yellow-brown color. Scientists suppose that the salty ocean hidden in the bowels of Europe could be heated by hydrothermal vents and potentially suitable for origin of life. Indirect evidence in favor of the existence of an ocean is the presence of a magnetic field around Europa, detected by NASA’s automatic spacecraft Galileo (it worked in the orbit of Jupiter from 1995 to 2003).
Today, Europa is considered one of the main places in the solar system where the existence of extraterrestrial life is possible. In 2009, University of Arizona professor Richard Greenberg calculated that the amount of oxygen in Europa’s oceans could be sufficient to support advanced life. According to his calculations, the oxygen released during the decomposition of ice under the influence of cosmic rays can penetrate into the ocean during the mixing of ice layers due to geological processes, as well as through cracks in the crust. According to Greenberg, due to this process, for several million years, the concentration of oxygen in Europa’s ocean could reach values that are much higher than in Earth’s oceans. This would allow Europa to support not only microscopic anaerobic life, but also larger aerobic organisms such as fish. However, it is worth noting that so far no signs of life have been found on this satellite, but the probable presence of liquid water prompts research expeditions to be sent there for a more thorough study.
In recent years, several promising projects have been developed to study Europa by space vehicles. One proposal, put forward in 2001, implies the creation of a large atomic melting probe (Cryobot) that would melt the ice until it reaches the subsurface ocean. After it reaches the water, an autonomous underwater vehicle (Hydrobot) would be launched, designed to gather the necessary samples and send them back to Earth. We must note that both Cryobot and Hydrobot should undergo extremely thorough sterilization in order to avoid contamination by terrestrial organisms and prevent pollution of the subsurface ocean. Unfortunately, this mission has not yet reached a serious planning stage.
Currently, NASA and the European Space Agency are working on the development of the automatic interplanetary station Europa Clipper, designed to study Europa from the point of view of the possibility of the existence of life within this space object. The project will be implemented in the mid-2020s. The Jupiter Icy Moon Explorer (JUICE) is scheduled to launch in 2023 to study the three moons of Jupiter (Ganymede, Callisto, and Europa). It is quite possible that in the near future we will witness new amazing achievements that will mark the beginning of a new milestone in the history of mankind — the Technological Age Of Space Discoveries.