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Is there life on other planets? This question has worried mankind for more than one thousand years. And scientists are trying to find at least some signs that there is life on other planets. Huge sound-detecting devices are aimed at space, which record every signal,

Is there life in boiling water? Until recently, it was believed that all, even the most persistent bacteria, perish in boiling water, but nature, as always, refuted this belief. At the bottom of the Pacific Ocean, super-hot springs with water temperatures ranging from 250 to 400 ° C were found,

Is there life in the Dead Sea? The Dead Sea is truly strange and, besides, it is far from the only name given by man to this one of the most unusual bodies of water on Earth. For the first time this sea began to be called "dead" by the ancient Greeks. The inhabitants of ancient Judea called

Is there life on Mars? Many people believe that there is life on Mars. But they do not distinguish fiction from real facts. Scientists have written a thousand times - is, is, is. The only question is who we will meet there - Aelita or someone else. Even now that American

This summer, the buzz news spread around the world. The American space telescope "Kepler" discovered "in the bowels" of our Galaxy a planet that is unusually reminiscent of the Earth. The find was nicknamed by some as a double, and who - "the cousin of the elder sister of the Earth."

It turns out that the discovery of life in space is also not far away? Why is colonization of the Moon by Russia delayed? We talked about this and other things with Yuri Shchekinov, an authoritative scientist, head. Department of Space Physics SFedU, Professor.

Yuri Shchekinov Photo: From personal archive

Fountains near ... Jupiter

Yuri Andreevich, the planet that caused a lot of hype, was named "Kepler-452b". They discovered it between the constellations Cygnus and Lyra. It is assumed to be akin to Earth. The planet is not much larger than ours. The local year is similar to the earthly one, it lasts 385 days. It is already clear that the mysterious planet is a solid body, and not an accumulation of gases or molten magma. There might be water. So there is a reasonable hope of finding life outside the Earth?

Figuratively speaking, there can be life between Swan and Lyra. Sometimes it seems that we are one step away from the main sensation - the discovery of life.

However, this is still not entirely true. There are many unanswered questions so far. That there is water on that planet is just speculation. Another thing is not clear: is there an atmosphere there, what is it? Possibly loose, salty. Maybe acid rain is pouring from the sky.

You see, we are trying to find a life similar to ours. We do not know the other. But it is possible that it could be completely different. And some other living organisms may not be afraid of acids.

In general, the hype around Kepler-452b seems to me excessive.

More hopes for habitability are now associated with two other contenders, also recently discovered by Kepler in our galaxy. The masses of those two planets are almost terrestrial. Their relief resembles ours. Apparently, both planets have high mountains and deep depressions, which are also essential for the origin of life. They both revolve around stars that resemble the sun. The radiation of those distant stars is even, calm, which is good.

They do not delete from the list of applicants for similarity to the Earth and an interesting planet from the Gliese-581 system. There must be water there. True, it is colder there than here. Surface temperature - 20 degrees Celsius. Apparently, the ocean is covered with a crust of ice. But this is not a prohibition at all for the emergence of life.

In general, very interesting research is now associated with the search for life outside the Earth in our solar system.

- Do you mean Mars?

And not only. On Saturn's moon Titan, methane river beds have been found. And methane is a liquid where bacteria can live. There is news that is completely sensational. Recently we saw how fountains periodically beat out from under the stone shell on Jupiter's moon Ganymede. Although until recently they could not have imagined this. They thought: what is Ganymede - stone and stone ... But, apparently, “work is in full swing” inside, some processes are going on ... Most likely, there is only primitive life - microbes, bacteria. Although who knows ...

Where are our brothers in mind?

Will we ever find a reasonable life? By the way, I heard that you are the author of an unusual hypothesis about where exactly life should be sought.

This hypothesis belongs to me and two major astrophysicists from a research center in the Indian city of Bangalore. In general, astrophysics in India is already very developed. We have prepared several articles. One will soon appear in the international journal Astrobiology.

What is the essence of our assumption? It is believed that life is more likely to be possible on planets orbiting stars that are close in age to our Sun. And he is 4.5 billion years old. But we were able (as it seems to us) to prove that life, at least primitive, may well exist near old stars, which are 11-13 billion years old!

As for your question ... I do not believe that we are alone in the universe. Just because of the large distances, we are not yet able to study other planets in detail. Therefore, humanity is like the inhabitants of a remote farm near the forest. They believe that there are no people around, only wolves walk. But they think so only because they cannot get out of the farm, climb the hill. And, looking around, see other people nearby, a big city.

Another thing is that the discovery of other civilizations will raise its own questions. Let me give you an example. Recently, the old planet was also included in the number of “applicants for habitability”. The star around which it revolves is 11 billion years old. This means that it is three times older than our Sun. And even assumptions are already being made: if there is a civilization there, it can be three times older than the earthly ...

Let's say time passes. They will come to us. But for them, communicating with us, apparently, will be akin to talking to Neanderthals. Let’s say, time passes. They will come to us. But for them, communicating with us, apparently, will be akin to talking to Neanderthals. Let’s say, time passes. They will come to us. But for them, communicating with us, apparently, will be akin to talking to Neanderthals.

Currently, people know only one planet on which there is life - this is the Earth. Although many media continue to publish information that life was found on some other planet. At such moments, a person has an internal disagreement, and he asks the question: but still, is there life in the Universe? The answer is neither simple nor straightforward.

Aliens - where are you?

To this day, scientists have not been able to find a single place where aliens could live. And here different questions arise: why are all scientists always looking for only such planets as ours? Why are they trying to find the conditions under which we live on all known space objects? Is there life in the Universe and where? For a start, it is worth thinking broadly: maybe, for the life of aliens, oxygen is not needed, and such, like ours, the composition of the air is destructive for them. Then these living entities will be different, not like us. For this reason, scientists are trying to find exactly the protein life of the terrestrial type.

Currently, an area in outer space has been identified that has conditions similar to those on Earth. It remains only to find out if there is life in the Universe. But for this you need to either fly to exoplanets, or develop a powerful telescope that can record various movements.

For life of the terrestrial type, it is necessary that the following conditions exist on the planet:

1. Liquid water.
2. Dense atmosphere.
3. Chemical diversity: simple and complex molecules.
4. The presence of a star that could carry energy to its surface.

While searching for new planets, scientists simply estimate the location of the "novelty". If she is in the habitable zone, then interest is immediately shown to her. After this, the atmosphere is studied, chemical diversity is determined, the presence of liquid water, a source of heat is determined. During the research, scientists are interested in: is there life in the Universe, or rather, on the planet found? And the more similar indicators with the Earth will be revealed, the higher the interest in the object.

The search for life

In 2009, NASA launched the Kepler spacecraft to search for exoplanets. These are objects that are located outside our solar system. A planet like this was first discovered in 1995. It was a tremendous event: to find an Earth-like planet near a star similar to our Sun. After that, a more active search for life in the Universe began. They began to develop a new, unique Kepler telescope.

Currently, more than 150 exoplanets have been discovered, of which two could be habitable. One of them is very much like the Earth, not only in the composition of the atmosphere and chemical elements, but also in other properties. Is there life on another planet, and on which one found by Kepler?

Planets "Kepler"

Years after the launch of the Kepler spacecraft, the news was published that it was possible to find a unique exoplanet, similar to Earth.

On April 17, 2014, NASA told the world about the existence of the planet Kepler-186, found in the constellation Cygnus. It is located in such a way that it falls into the habitable zone. However, it orbits a red dwarf that is colder than the sun. Based on this, scientists came to the conclusion that it is unlikely that there will be normal conditions for life. Red dwarfs are characterized by frequent magnetic flares that emit X-rays that can be harmful to nascent life. But is there life on other planets, and on which ones?

In July 2015, NASA announced the next unique find - Kepler-452b. is in the habitable zone, and revolves around a yellow dwarf. She has satellites that may be habitable. Although in fact, no scientist can say for sure whether there is water and land there, since no one has been there and will not be there for many years. The planet revolves around its sun for 385 Earth days.

Close exoplanet

So where to look for brothers in mind, in which galaxy, on which planet? It is safe to name only one place where you can find brothers in mind. It is located in the Milky Way galaxy, in the solar system, on planet Earth. But with regard to other places, no one can say for sure whether there is still a life similar to ours.

In August 2016, the exoplanet Proxima b was discovered near the star Proxima Centauri. She is closest to us.

The Earth is located at a distance of 1 astronomical unit from the Sun, and Proxima b is located at a distance of 0.5 units from its Sun, but its star shines and warms weaker than our star. Because of this, even at such distances, Proxima b falls into the habitable zone.

The exoplanet does not rotate around its axis, that is, it is like our Moon captured by the Earth: it always moves nearby, but does not turn its dark side. Likewise, an exoplanet: it is captured by its own star and is always turned to it with one side. As a result, one side is hot and the other cold. But, according to scientists, there are optimal conditions for a normal life in the transition zone.

Moon of saturn

Trying to answer the question of whether there is life in the Universe besides the Earth, scientists have found that there are optimal conditions for the development of life. By itself, this object is small - about 500 km (the size of the Moscow region). It has ice, oceans, hot springs, rich chemical composition.

One theory of life on Earth suggests that it could have originated at the bottom of the ocean, where there were hot springs. This satellite is the second planet on which there could be life. The first place in the search for an answer to the question of whether there is intelligent life in the Universe is occupied by Mars. A lot of information is already known about him, and each time scientists publish new discoveries related to this planet. So, it was already possible to find out that there is ice here, and once the water was in a liquid state.

Looking for life in the future

Now work is underway to create a unique twenty-meter telescope that will study exoplanets. Various institutions are involved in the project. If everything goes according to plan, then in 2022, scientists will be able to examine in more detail objects in the Universe.

Another miracle of technology is planned to be built in Europe. It will be a thirty-meter telescope capable of examining even the faintest and most distant objects that are not visible to existing devices. This kind of giant telescope is predicted to appear in the mid-1920s.

Conclusion

So far, astronomers, astrophysicists have not been able to find life on other planets. And only ufologists say that space is teeming with alien creatures. There is a lot of information about various flying objects visiting the Earth, about kidnapping people, alien bases. Maybe this is all there is, but we are unlikely to find out about this in the near future. For many centuries we have been told that we are alone in the Universe, but maybe somewhere else there is life that we do not yet know about. And, perhaps, in the near future, scientists will be able to find inhabited planets, to see the light of foreign cities.

The guest of the "Space Environment" program is Georgy Managadze, head of the laboratory of active diagnostics at the Space Research Institute of the Russian Academy of Sciences, professor, full member of the International Academy of Astronautics.

The host of the program is Maria Kulakovskaya.

The search for life in space

The bricks of the universe are found in the Galaxy almost every year, from simple methane to complex organic compounds. For half a century of the space era, 140 types of molecules have been discovered in interstellar space and the gas and dust disks surrounding the stars, including ethyl alcohol, formaldehyde and formic acid. Until recently, scientists did not understand exactly how living cells were formed from the smallest particles in space.

Says Vladimir Surdin, senior researcher at the Astronomical Institute of Moscow State University named after Sternberg: "Try to understand how in a hundred million years from nothing, from simple inert substances, such complex RNA, DNA and other proteins were obtained that provide our life today."

Recently, a team of Russian scientists from the Space Research Institute proved that the synthesis of organic molecules in space can occur when the smallest particles of matter collide at ultra-high speeds, up to thousands of kilometers per second. In this way, amino acids, the molecules that make up proteins, the basis of earthly life, can be born.

Today, expeditions to search for extraterrestrial life are preparing to be sent to Jupiter's satellite, Europe. Spacecraft of the international project "Laplace" will take samples of the relict soil and determine whether organic life is possible outside the Earth.

Elena Vorobyova, senior researcher at Moscow State University, says: “If we find life on some planetary bodies, it really can mean that either life can arise many times, or life has some single source, but can be carried in space. What forms can accept life? Is the biological life we ​​know of, based on carbon? Or is it necessary to look for some similarities, but different from the terrestrial form of life? And such tasks are also theoretically worked out. "

The satellites of the planets are of particular interest to scientists, since in the process of evolution they have been preserved in their original state.

Vladimir Surdin, senior researcher at the Astronomical Institute of Moscow State University named after Sternberg: “Europe, the second moon from Jupiter, is covered with a thick layer of ice. Europe has whole lakes or even an ocean of liquid water. "

It is in the water of Jupiter's moon that scientists hope to find life, its simplest forms. In the original nuclei of life, according to scientists, there are all evolutionary possibilities.

Vladimir Surdin continues: "The ocean of Europe is an ideal place to live. Under the ice dome there is water at zero degrees. We do not know, really, what it is, salty or sour. How much it tastes, so to speak. It still needs to be checked. . But, one way or another, on Earth, whatever the water, we always find life in it. "

The same experiments in the Antarctic Lake Vostok showed that the ice particles are still inhabited by bacteria, moreover, living bacteria. And if life is found on Phobos, Europa or Mars, which can withstand harsh space conditions, this will indicate that space, until recently considered uninhabited, is saturated with biological life.

Interview

Kulakovskaya: In our studio - the head of the laboratory of active diagnostics of the Institute of Space Research of the Russian Academy of Sciences, professor, full member of the International Academy of Astronautics Georgy Managadze. Hello!

Georgy Georgievich, I have been interested in the question for a very long time: is space inhabited, and is there life in it? What conclusion are you leaning towards? What does your institute's research say?

Managadze: As far as I understand and perceive today's scientific realities, it is possible that there is microbial life in the solar system, in our system. Outside the solar system, we have no chance of not having one. The experiments I have done show that life is easy to start. It is another matter whether it will reach some form of civilization, will it survive or not? This is a different question.

Kulakovskaya: Where do scientists hope to find traces of organic life?

Managadze: A very curious situation turns out. Let's say our American friends, I treat them very well, they are intelligent, good people, they spend a lot of money and conduct good research, but sometimes they lose their realism. For example, they will find an amino acid somewhere, say, in meteorites. They immediately say that life originated in space. And this is not the case. In order for life to arise in space, you need not only an amino acid, but also many other conditions. It should be a whole cascade. Life can exist in microbial form, naturally. On Mars, for some reason, it seems to me, there is no doubt that there is life, in the depths of the planet, inside.

Kulakovskaya: Maybe we brought her there?

Managadze: May be we. Maybe she was brought there from us. It does not matter. She could be born herself on such bodies. In any case, I see conditions for the development of microbial life on Europa, on Enceladus and even on Titan. Because Titan is supposed to have a surface ocean, water. Maybe this explains the huge amount of methane on Titan. And how it could have originated there is a serious question. My basic concept is that organic matter, and not only organic matter, but also large pieces, up to homogeneous (as in science, homochiral) molecules, living matter could have arisen during a meteorite impact. Because a meteorite impact has tremendous energy.

Let's say a Yucatan meteorite that fell in Mexico 65 million years ago broke a crater 30 kilometers deep. On other bodies at such a depth, even higher, there may already be water. During the impact of a meteorite, organic matter is formed. Organic matter, getting into this environment, into water, at a permissible temperature due to tidal forces, some other mechanisms could already catch on, develop and exist. We are planning such an experiment in about six to seven years - a flight to Europa (Jupiter's moon). And I think there is every reason to hope that we will find something.

Kulakovskaya: Where do organic compounds come from in space?

Managadze: Organic compounds on Earth due to the fact that we produce them. And in outer space, there are stars that emit a lot of carbon. This carbon is deposited on the surface of the dust (interstellar gas, dusty environment). There we also observe organic matter using radio telescopes. Found 80 or 110 organic compounds, and already quite complex. There is such a hypothesis that carbon sticks to the surface of a grain of dust. There is a terrible cold - minus four degrees on an absolute scale - this is the lowest of all. Very cold. Oxygen and hydrogen also adhere, and then they combine. This process is very difficult to imagine in such cold conditions. Despite the fact that the late Academician Gol'dansky came up with a tunneling mechanism, as if they could be connected.

The mechanism that I propose works great. This is not fiction. We reproduce these processes in the laboratory. Suppose two grains of dust can be accelerated to high speeds in different cosmic processes - when passing through a shock wave, in the process of light pressure from stars. They can accelerate above 20 kilometers per second and up to thousands of kilometers per second. The collision of these dust particles is the process of their destruction. So they are destroyed. Dust particles appear during the dying of stars, the star throws them out. They dangle, then accelerate, collide and are destroyed. But during this destruction, a plasma torch is formed. It possesses completely unusual catalytic activity, convenient for the creation of new substances. Because the plasma itself is a catalytic medium.

Kulakovskaya: But is it always carbon-based life? Could there be other life besides the biological form?

Managadze: That's a very good question. Today it is difficult to imagine what else life could be. I can't say that either. And when they say "silicon", "silicon" and so on, my experiments do not show this possibility. Because carbon is a very good substance. An active, impudent substance. If released from everything, it instantly captures and forms organic compounds in the plasma torch. Plasma torch, expanding and flying away, cools down. At first, it has a huge temperature, it can reach a million degrees. And then, during adiabatic expansion (this is a special type of expansion, on the principle of which our refrigerators work), the gases expand, and it cools down. In these processes, organics can become more complex.

Another very important thing is that in these processes, when carbon expands, what we received is fixed, and further becomes even more complicated. No reverse, no fall apart. Do you understand? In any chemical reaction, saturation occurs somewhere, and everything goes back, the collapse begins. And there - no. Complex organic matter is formed. I believe that in such a plasma torch a substance can even be generated that will have all the signs of living matter. She can reproduce and have the simplest genetic code.

Kulakovskaya: The studies of our scientists in Antarctica prove that microorganisms can live in ice, and in boiling water, and at the bottom of the Pacific Ocean under enormous pressure.

Managadze: Wherever you want. I am a physicist, I emphasize again . But if, for example, there was a blow, and everything fell asleep, excellent conditions arise for the further evolution of the microorganism. Why did I tell you that amino acid means nothing in space. We need that after the birth or appearance of living matter, it would get into an environment where it could develop. What kind of environment is it? Can you imagine, the most primitive living system has formed, which cannot even be called a bacterium. It's just a nucleotide stick along which a protein moves back and forth and produces its own kind. They may not have a shell. If we imagine that today's microbial organism is about the size of a blue whale (40 tons), then this stick is about the size of a hen's egg. Imagine, it is so primitive.

Moreover, this primitive living system does not even have any enzymatic abilities. She can only reproduce, reproduce her own kind and live according to Darwinian selection. She does not need food, but organic compounds. And during a meteorite impact, simple organic matter is synthesized, which it can eat and live. Moreover, another good point. Let's say a meteorite with a diameter of 10 kilometers fell. A 100-kilometer crater is formed. In this crater for ten million years, it is very easy to calculate, if the temperature is acceptable, the ice will melt, there will be water. In ten million years, this simplest thing can develop.

Kulakovskaya: Do you think that life on Earth originated as a result of the fall of a meteorite?

Managadze: Yes. This is a very good mechanism. Moreover, it is consistent. At different times, scientists have come to a different scenario. Such an empirical approach. They got the result and said: "Ah! It happened under water" or "It happened in space." Because in the process of interaction, carbon must come from somewhere. In my concept, this carbon appears precisely in the nuclei of comets, carbonaceous chondrites, where carbon is actually observed. Carbonaceous chondrites are the bodies that made up the Earth. This is the first thing. Further, these bodies must have tremendous energy in order to process this material. That is, falling, they turn into plasma, and in this plasma torch, like in a plasma generator of an industrial system, where various substances are synthesized, which are not synthesized in chemistry at all, there must be synthesized into organic compounds, in the presence of carbon.

But this is not enough. They must be somehow ordered, make up a reasonable structure. Without these processes, the origin of life is impossible. Random processes will not lead to the birth of life. In these substances, the original symmetry must be broken. You, me, all living things, proteins are composed of L-amino acids. It is still unknown when the symmetry breaking occurred. I have some ideas on this score. I explain it quite easily. The fields that arise in the plasma plume meet the requirements for generating fields. They are called giralds. "Hiro" is the hand. The left and right hand are such an analogy. Then they have to create a very clean environment. The macromolecule must be made of only L-amino acids. And then a barely living creature appears, after which it falls into a crater, where it survives. These sequences must be mandatory. And here a cascade is formed. Because if we do not follow this cascade ... For example, in the early scenarios, when they said "the sun is shining." The energy density of the Sun is less than the impact energy density. This is not enough. The sun gives birth to, for example, one amino acid where you sit, another amino acid where I sit, and they can never meet. This was formerly called the concentration gap.

Kulakovskaya: This is just understandable.

Managadze: Of course.

Kulakovskaya: Georgy Georgievich, one of the most popular nightmares in science fiction is the interaction of alien organisms with earthlings. How realistic are these fears? If, for example, microbes from the same Europe get to the Earth?

Managadze: If these are terrestrial microbes, I think our microbes will defeat them. If it is any other microbes, this is a very difficult question. I myself am interested in this issue. There are prerequisites that microbes that are unearthly may exist on Earth. Nobody denies this, I have seen many publications. The fact is that our organisms, microbes, it turns out, work on phosphorus. It has not been proven yet, but there are suggestions that instead of phosphorus, which is a very important link in nucleic acids, there may be some other element - a substitute for phosphorus. I think our microbes, terrestrial type, are stronger.

Kulakovskaya: Georgy Georgievich, if, after all, scientists prove that life in the solar system really exists, what will be the next steps?

Managadze: I have been working very closely with Academician Sagdeev for a long time. In his opinion, if we find microbial life anywhere, it will be the biggest phenomenon of the next millennium - the discovery of life. If we find life, it will testify that life is doomed to be born. But I do not know the algorithm for how matter came to life. Honestly, I don't know. But, since we are talking, it means that nature somehow bypassed ...

Kulakovskaya: Somehow it worked out.

Managadze: And I, as a person who has the ability to experiment, to attract different cosmic conditions, knowing this, I see that conditions for this can be created. And I think that life will be found on many bodies. There is such Drake's formula. He came up with a formula in the 60s. There are coefficients. Multiplying the coefficients gives the probability of the existence of life in our Galaxy. Not only life, but even civilizations. These coefficients are the most controversial questions: how many stars are in our Galaxy (the more, the better), how many of these stars are satellite systems, which of them are similar to Earth. But the most tricky coefficients relate to the origin of life. If we believe that only on Earth (in our Galaxy) there is life, then Drake's formula shows that this is an exceptional case. And if we show that there is life on Earth, life on Mars, somewhere else, then it will be absolutely good. We must all the time look at the sky and say: "When will they arrive."

Kulakovskaya: Looking for another civilization?

Managadze: Yes, when will this civilization come to us. I am very sorry that what I have been doing and I am doing now fell into a terrible era when no one is interested in anything, when people do not listen to each other. When we talk about the dawn of civilization, curiosity is very important. Monkeys are found on Kilimanjaro, above, in the snow. Why are they going there, no one knew. Finally, the scientists came up with the idea.

Kulakovskaya: Curiosity?

Managadze: But curiosity disappears from us.

Kulakovskaya: Curiosity made a man out of a monkey.

Managadze: Absolutely right. Especially when you come into contact with the unknown, it is so interesting.

Kulakovskaya: It is very interesting. I thank you, Georgy Georgievich, for giving us such a wonderful and interesting lecture. Thank you very much.

Managadze: Thank you too. I am always glad to cooperate with your radio, because you try, and I try too, looking at you. Thanks.

Listen to the full version of the program

There is nothing more exciting than the search for life and intelligence in the universe. The uniqueness of the earth's biosphere and human intelligence challenges our belief in the unity of nature. A person will not rest until he has solved the riddle of his origin. On this path, it is necessary to go through three important steps: to learn the secret of the birth of the Universe, to solve the problem of the origin of life and to understand the nature of reason.

Astronomers and physicists are studying the Universe, its origin and evolution. Biologists and psychologists are engaged in the study of living beings and the mind. And the origin of life worries everyone: astronomers, physicists, biologists, chemists. Unfortunately, we are familiar with only one form of life - protein and only one place in the Universe where this life exists - planet Earth. And unique phenomena, as you know, are difficult to scientific research. Now, if it was possible to find other inhabited planets, then the riddle of life would be solved much faster. And if intelligent beings would be found on these planets ... The spirit captures, one has only to imagine the first dialogue with brothers in mind.

But what are the real prospects for such a meeting? Where in space can you find suitable places to live? Can life originate in interstellar space, or does this require the surface of planets? How to contact other sentient beings? There are many questions ...

Searching for life in the solar system

The LUNA is the only celestial body where earthlings have been able to visit and the soil of which has been studied in detail in the laboratory. No traces of organic life have been found on the Moon.

The fact is that the Moon does not have and never had an atmosphere: its weak gravitational field cannot keep gas near the surface. For the same reason, there are no oceans on the Moon - they would evaporate. The surface of the Moon, not covered by the atmosphere, heats up to 130 ° C during the day, and cools down to -170 ° C at night. In addition, ultraviolet and X-rays of the Sun, which are harmful to life, penetrate the lunar surface without hindrance, from which the Earth is protected by the atmosphere. In general, there are no conditions for life on the lunar surface. True, under the top layer of the soil, already at a depth of 1 m, temperature fluctuations are almost not felt: there it is constantly about -40 ° C. But still, in such conditions, life probably cannot arise.

Neither cosmonauts nor automatic stations have yet visited the small planet MERCURY closest to the Sun. But people know something about it thanks to research from the Earth and from the American spacecraft "Mariner-10" flying near Mercury (1974 and 1975). Conditions there are even worse than on the moon. There is no atmosphere, and the surface temperature varies from –170 to 450 ° С. Under the ground, the average temperature is about 80 ° C, and it naturally increases with depth.

VENUS in the recent past was considered by astronomers to be almost an exact copy of the young Earth. Guesses were made, what is hidden under its cloud layer: warm oceans, ferns, dinosaurs? Alas, due to its proximity to the Sun, Venus is not at all like Earth: the pressure of the atmosphere at the surface of this planet is 90 times higher than that of the Earth, and the temperature is about 460 ° C during the day and at night. Several automatic probes landed on Venus, they did not search for life: it is difficult to imagine life in such conditions. It's not so hot over the surface of Venus: at an altitude of 55 km, the pressure and temperature are the same as on Earth. But Venus's atmosphere is made up of carbon dioxide, and clouds of sulfuric acid float in it. In a word, it is also not the best place to live.

MARS was not without reason considered a habitable planet. Although the climate there is very harsh (in summer days the temperature is about 0 ° С, at night –80 ° С, and in winter it reaches –120 ° С), it is still not hopelessly bad for life: it exists in Antarctica and on the peaks of the Himalayas ... However, there is another problem on Mars - an extremely rarefied atmosphere, 100 times less dense than on Earth. It does not save the surface of Mars from the harmful ultraviolet rays of the Sun and does not allow water to be in a liquid state. On Mars, water can only exist in the form of steam and ice. And it really is there, at least in the polar caps of the planet. Therefore, with great impatience everyone was waiting for the results of the search for Martian life undertaken immediately after the first successful landing on Mars in 1976 of the automatic stations "Viking-1 and -2". But they disappointed everyone: life was not discovered. True, this was only the first experiment. The search continues.

GIANT PLANETS. The climate of Jupiter, Saturn, Uranus and Neptune does not at all correspond to our ideas about comfort: it is very cold, terrible gas composition (methane, ammonia, hydrogen, etc.), there is practically no solid surface - only a dense atmosphere and an ocean of liquid gases. All of this is very unlike Earth. However, in the era of the origin of life, the Earth was not at all the same as it is now. Its atmosphere was more like Venusian and Jupiterian, except that it was warmer. Therefore, in the near future, the search for organic compounds in the atmosphere of the giant planets will certainly be carried out.

SATELLITES OF PLANETS AND COMETS. The "family" of satellites, asteroids and cometary nuclei is very diverse in its composition. On the one hand, it includes the huge satellite of Saturn, Titan, with a dense nitrogen atmosphere, and on the other, small ice blocks of cometary nuclei that spend most of their time on the far periphery of the solar system. There has never been a serious hope of discovering life on these bodies, although the study of organic compounds on them as precursors of life is of particular interest. Recently, the attention of exobiologists (specialists in extraterrestrial life) has been attracted by Jupiter's moon Europa. There should be an ocean of liquid water under the ice crust of this moon. And where there is water, there is life.

Complex organic molecules are sometimes found in meteorites that have fallen to the ground. At first there was a suspicion that they fall into meteorites from the earth's soil, but now their extraterrestrial origin has been completely reliably proven. For example, the Murchison meteorite, which fell in Australia in 1972, was picked up the very next morning. In its substance, 16 amino acids were found - the main building blocks of animal and plant proteins, and only 5 of them are present in terrestrial organisms, and the remaining 11 are rare on Earth. In addition, among the amino acids of the Murchison meteorite, left and right molecules (mirror symmetrical to each other) are present in equal proportions, while in terrestrial organisms they are mainly left. In addition, in the molecules of the meteorite, carbon isotopes 12C and 13C are presented in a different proportion than on Earth. This undoubtedly proves that amino acids, as well as guanine and adenine, which are constituents of DNA and RNA molecules, can form independently in space.

So, so far in the solar system, nowhere else except the Earth, life has not been found. Scientists do not have high hopes on this score; most likely the Earth will be the only living planet. For example, the climate of Mars in the past was milder than it is now. Life could arise there and advance to a certain stage. There is a suspicion that some of the meteorites hitting Earth are ancient fragments of Mars; in one of them, strange traces were found, possibly belonging to bacteria. These are preliminary results, but even they are generating interest in Mars.

Conditions for life in space

In space, we meet a wide range of physical conditions: the temperature of a substance varies from 3-5 K to 107-108 K, and the density - from 10-22 to 1018 kg / cm3. Among such a wide variety, it is often possible to find places (for example, interstellar clouds) where one of the physical parameters from the point of view of terrestrial biology favors the development of life. But only on planets can all the parameters necessary for life coincide.

PLANETS NEAR STARS. The planets must be no less than Mars to keep air and water vapor at their surface, but not as huge as Jupiter and Saturn, whose extended atmosphere does not allow the sun's rays to reach the surface. In short, planets such as Earth, Venus, possibly Neptune and Uranus, under favorable circumstances, can become the cradle of life. And these circumstances are quite obvious: stable radiation of the star; a certain distance from the planet to the luminary, which provides a comfortable temperature for life; the circular shape of the planet's orbit, which is possible only in the vicinity of a solitary star (i.e., a single or a component of a very wide binary system). This is the main thing. How often does a set of similar conditions occur in space?

There are quite a few single stars - about half of the stars in the Galaxy. Of these, about 10% are similar to the Sun in temperature and luminosity. True, not all of them are as calm as our star, but approximately every tenth is similar to the Sun in this respect. Observations of recent years have shown that planetary systems are likely to form around a significant portion of moderate-mass stars. Thus, the Sun with its planetary system should resemble about 1% of the stars in the Galaxy, which is not so little - billions of stars.

BIRTH OF LIFE ON THE PLANETS. In the late 50s. XX century American biophysicists Stanley Miller, Juan Oro, Leslie Orgel in laboratory conditions simulated the primary atmosphere of the planets (hydrogen, methane, ammonia, hydrogen sulfide, water). They illuminated flasks with a gas mixture with ultraviolet rays and excited them with spark discharges (on young planets, active volcanic activity should be accompanied by strong thunderstorms). As a result, curious compounds were very quickly formed from the simplest substances, for example, 12 out of 20 amino acids that form all proteins of terrestrial organisms, and 4 out of 5 bases that form RNA and DNA molecules. Of course, these are only the most elementary "bricks" from which terrestrial organisms are built according to very complex rules. It is still unclear how these rules were developed and fixed by nature in RNA and DNA molecules.

ZONES OF LIFE. Biologists see no other basis for life other than organic molecules - biopolymers. While for some of them, for example DNA molecules, the most important is the sequence of monomer units, for most other molecules - proteins and especially enzymes - their spatial form, which is very sensitive to ambient temperature, is the most important. As soon as the temperature rises, the protein is denatured - it loses its spatial configuration, and with it its biological properties. In terrestrial organisms, this occurs at a temperature of about 60 ° C. Almost all terrestrial life forms are destroyed at 100-120 ° C. In addition, the universal solvent - water - under such conditions turns into vapor in the Earth's atmosphere, and at temperatures below 0 ° C - into ice. Therefore, we can assume that the temperature range favorable for the occurrence is 0-100 ° C.