Chapter from the book. "Astronomy". Chapter from the book Lectures by Sourdin on astronomy September

Surdin Vladimir Georgievich (April 1, 1953, Miass, Chelyabinsk region) - Russian astronomer, candidate of physical and mathematical sciences, associate professor at Moscow State University, senior researcher at the State Astronomical Institute. Sternberg (SAI) Moscow State University.

Having graduated from the Faculty of Physics of Moscow State University, Vladimir Georgievich has been working at the State Inspectorate for the past three decades. His research interests range from the origin and dynamical evolution of stellar systems to the evolution of the interstellar medium and the formation of stars and star clusters.

Vladimir Georgievich gives several courses on astronomy and stellar dynamics at Moscow State University and popular lectures at the Polytechnic Museum.

Books (11)

Astrology and science

Is there a connection between astrology and science? Some argue that astrology itself is a science, while others believe that astrology is nothing more than star divination. The book explains how scientists view astrology, how they check astrological forecasts, and which of the great astronomers were astrologers and to what extent.

On the cover: The painting by the Dutch artist Jan Vermeer (1632-1675), now kept in the Louvre (Paris), depicts an astronomer. Or an astrologer?

Galaxies

The fourth book in the Astronomy and Astrophysics series contains an overview of modern ideas about giant star systems - galaxies. The history of the discovery of galaxies, their main types and classification systems are described. The basics of the dynamics of stellar systems are given. The galactic neighborhoods closest to us and work on the global study of the Galaxy are described in detail. Data are presented on various types of galaxy populations—stars, interstellar medium, and dark matter. The features of active galaxies and quasars are described, as well as the evolution of views on the origin of galaxies.

The book is aimed at junior students of natural science faculties of universities and specialists in related fields of science. The book is of particular interest to astronomy lovers.

Dynamics of stellar systems

The great astronomical discoveries of Nicolaus Copernicus, Tycho Brahe, Johannes Kepler, and Galileo Galilei marked the beginning of a new scientific era, stimulating the development of the exact sciences.

Astronomy had the great honor of laying the foundations of natural science: in particular, the creation of a model of the planetary system led to the emergence of mathematical analysis.

From this brochure the reader will learn about many fantastic achievements in astronomy that have been made in recent decades.

Stars

The book “Stars” from the “Astronomy and Astrophysics” series contains an overview of modern ideas about stars.

It tells about the names of constellations and the names of stars, about the possibility of observing them at night and during the day, about the main characteristics of stars and their classification. The main attention is paid to the nature of stars: their internal structure, energy sources, origin and evolution. The late stages of stellar evolution leading to the formation of planetary nebulae, white dwarfs, neutron stars, as well as novae and supernovae are discussed.

Mars. The Great Controversy

In the book “Mars. The Great Confrontation" talks about exploration of the surface of Mars in the past and present.

The history of observations of Martian canals and the discussion about the possibility of life on Mars, which took place during the period of its study by means of ground-based astronomy, are described in detail. The results of modern studies of the planet, its topographic maps and photographs of the surface obtained during the period of the great opposition of Mars in August 2003 are presented.

Elusive Planet

A fascinating story from a specialist about how they search for and find new planets in the Universe.

Sometimes everything is decided by a lucky chance, but more often - years of hard work, calculations and many hours of vigil at the telescope.

UFO. Notes of an astronomer

The UFO phenomenon is a multifaceted phenomenon. Journalists in search of sensations, scientists in search of new natural phenomena, military men who fear the machinations of the enemy, and simply inquisitive people who are confident that “there is no smoke without fire” are interested in it.

In this book, an astronomer—an expert on celestial phenomena—expresses his view on the UFO problem.

Travel to the Moon

The book talks about the Moon: about its observations using a telescope, about the study of its surface and interior by automatic devices, and about manned expeditions by astronauts under the Apollo program.

Historical and scientific data about the Moon, photographs and maps of its surface, descriptions of spacecraft and a detailed account of expeditions are provided. The possibilities of studying the Moon by scientific and amateur means and the prospects for its development are discussed.

The book is intended for those who are interested in space research, begin independent astronomical observations, or are passionate about the history of technology and interplanetary flights.

Exploration of distant planets

The problems are preceded by a brief historical introduction. The publication is intended to help in teaching astronomy in higher education institutions and schools. It contains original tasks related to the development of astronomy as a science.

Many problems are of an astrophysical nature, so the manual can also be used in physics classes.

solar system

The second book in the Astronomy and Astrophysics series provides an overview of the current state of the study of planets and small bodies in the Solar System.

The main results obtained in ground-based and space-based planetary astronomy are discussed. Modern data on the planets, their satellites, comets, asteroids and meteorites are presented. The presentation of the material is mainly aimed at junior students of natural science faculties of universities and specialists in related fields of science.

The book is of particular interest to astronomy lovers.

The inner region of the Solar System is inhabited by a variety of bodies: large planets, their satellites, as well as small bodies - asteroids and comets. Since 2006, a new subgroup has been introduced into the group of planets - dwarf planets ( dwarf planet), possessing the internal qualities of planets (spheroidal shape, geological activity), but due to their low mass, are not able to dominate in the vicinity of their orbit. Now the 8 most massive planets - from Mercury to Neptune - have been decided to be called simply planets ( planet), although in conversation astronomers, for the sake of clarity, often call them “major planets” to distinguish them from dwarf planets. The term "minor planet", which had been applied to asteroids for many years, is now deprecated to avoid confusion with dwarf planets.

In the region of large planets, we see a clear division into two groups of 4 planets each: the outer part of this region is occupied by giant planets, and the inner part is occupied by much less massive terrestrial planets. The group of giants is also usually divided in half: gas giants (Jupiter and Saturn) and ice giants (Uranus and Neptune). In the group of terrestrial planets, a division in half is also emerging: Venus and Earth are extremely similar to each other in many physical parameters, and Mercury and Mars are an order of magnitude inferior to them in mass and are almost devoid of an atmosphere (even Mars has an atmosphere hundreds of times smaller than Earth’s, and Mercury is practically absent).

It should be noted that among the two hundred satellites of the planets, at least 16 bodies can be distinguished that have the internal properties of full-fledged planets. They often exceed dwarf planets in size and mass, but at the same time they are controlled by the gravity of much more massive bodies. We are talking about the Moon, Titan, the Galilean satellites of Jupiter and the like. Therefore, it would be natural to introduce a new group into the nomenclature of the Solar System for such “subordinate” objects of the planetary type, calling them “satellite planets”. But this idea is currently under discussion.

Let's return to terrestrial planets. Compared to giants, they are attractive because they have a solid surface on which space probes can land. Since the 1970s. automatic stations and self-propelled vehicles of the USSR and the USA repeatedly landed and successfully worked on the surface of Venus and Mars. There have been no landings on Mercury yet, since flights to the vicinity of the Sun and landing on a massive atmosphereless body are technically very difficult.

While studying terrestrial planets, astronomers do not forget the Earth itself. Analysis of images from space has made it possible to understand a lot about the dynamics of the earth’s atmosphere, the structure of its upper layers (where airplanes and even balloons do not rise), and the processes occurring in its magnetosphere. By comparing the structure of the atmospheres of Earth-like planets, one can understand a lot about their history and more accurately predict their future. And since all higher plants and animals live on the surface of our (or not only our?) planet, the characteristics of the lower layers of the atmosphere are especially important for us. This lecture is devoted to terrestrial planets, mainly their appearance and conditions on the surface.

The brightness of the planet. Albedo

Looking at the planet from afar, we can easily distinguish between bodies with and without an atmosphere. The presence of an atmosphere, or rather the presence of clouds in it, makes the appearance of the planet changeable and significantly increases the brightness of its disk. This is clearly visible if we arrange the planets in a row from completely cloudless (without atmosphere) to completely covered by clouds: Mercury, Mars, Earth, Venus. Rocky, atmosphereless bodies are similar to each other to the point of almost complete indistinguishability: compare, for example, large-scale photographs of the Moon and Mercury. Even an experienced eye has difficulty distinguishing between the surfaces of these dark bodies, densely covered with meteorite craters. But the atmosphere gives any planet a unique appearance.

The presence or absence of an atmosphere on a planet is controlled by three factors: temperature, gravitational potential at the surface and the global magnetic field. Only the Earth has such a field, and it significantly protects our atmosphere from solar plasma flows. The Moon lost its atmosphere (if it had one at all) due to its low critical velocity at the surface, and Mercury lost its atmosphere due to high temperatures and powerful solar wind. Mars, with almost the same gravity as Mercury, was able to retain the remnants of the atmosphere, since due to its distance from the Sun it is cold and not so intensely blown by the solar wind.

In terms of their physical parameters, Venus and Earth are almost twins. They have very similar size, mass, and therefore average density. Their internal structure - crust, mantle, iron core - should also be similar, although there is no certainty about this yet, since seismic and other geological data on the bowels of Venus are missing. Of course, we did not penetrate deeply into the bowels of the Earth: in most places - 3-4 km, in some points - 7-9 km, and only in one - 12 km. This is less than 0.2% of the Earth's radius. But seismic, gravimetric and other measurements make it possible to judge the Earth’s interior in great detail, while for other planets there is almost no such data. Detailed gravitational field maps have been obtained only for the Moon; heat flows from the interior have been measured only on the Moon; Seismometers have so far only worked on the Moon and (not very sensitive) on Mars.

Geologists still judge the internal life of planets by the features of their solid surface. For example, the absence of signs of lithospheric plates on Venus significantly distinguishes it from the Earth, in the evolution of the surface of which tectonic processes (continental drift, spreading, subduction, etc.) play a decisive role. At the same time, some indirect evidence points to the possibility of plate tectonics on Mars in the past, as well as tectonics of ice fields on Europa, a satellite of Jupiter. Thus, the external similarity of the planets (Venus - Earth) does not guarantee the similarity of their internal structure and processes in their depths. And planets that are different from each other can exhibit similar geological phenomena.

Let's return to what is available to astronomers and other specialists for direct study, namely, the surface of the planets or their cloud layer. In principle, the opacity of the atmosphere in the optical range is not an insurmountable obstacle to studying the solid surface of the planet. Radar from the Earth and from space probes made it possible to study the surfaces of Venus and Titan through their atmospheres opaque to light. However, these works are sporadic, and systematic studies of planets are still carried out with optical instruments. And more importantly, optical radiation from the Sun serves as the main source of energy for most planets. Therefore, the ability of the atmosphere to reflect, scatter and absorb this radiation directly affects the climate at the surface of the planet.

The brightness of a planet's surface depends on its distance from the Sun and the presence and properties of its atmosphere. The cloudy atmosphere of Venus reflects light 2–3 times better than the partially cloudy atmosphere of the Earth, and the atmosphereless surface of the Moon is three times worse than the Earth's atmosphere. The brightest luminary in the night sky, not counting the Moon, is Venus. It is very bright not only because of its relative proximity to the Sun, but also because of the dense cloud layer of concentrated sulfuric acid droplets that perfectly reflects light. Our Earth is also not too dark, since 30–40% of the Earth's atmosphere is filled with water clouds, and they also scatter and reflect light well. Here is a photograph (Fig. 4.3), where the Earth and the Moon were simultaneously included in the frame. This photo was taken by the Galileo space probe as it flew past Earth on its way to Jupiter. Look how much darker the Moon is than the Earth and generally darker than any planet with an atmosphere. This is a general pattern: atmosphereless bodies are very dark. The fact is that under the influence of cosmic radiation, any solid substance gradually darkens.

The statement that the surface of the Moon is dark usually causes bewilderment: at first glance, the lunar disk looks very bright, and on a cloudless night it even blinds us. But this is only in contrast to the even darker night sky. To characterize the reflectivity of any body, a quantity called albedo. This is the degree of whiteness, that is, the coefficient of light reflection. Albedo equal to zero is absolute blackness, complete absorption of light. An albedo equal to one is total reflection. Physicists and astronomers have several different approaches to determining albedo. It is clear that the brightness of an illuminated surface depends not only on the type of material, but also on its structure and orientation relative to the light source and the observer. For example, fluffy, freshly fallen snow has one reflectance value, but snow that you step on with your boot has a completely different one. And the dependence on orientation can easily be demonstrated with a mirror, letting in sunbeams. The exact definition of albedo of various types is given in the chapter “Quick Reference” (p. 265). Familiar surfaces with different albedo are concrete and asphalt. Illuminated by the same fluxes of light, they exhibit different visual brightness: freshly washed asphalt has an albedo of about 10%, while clean concrete has an albedo of about 50%.

The entire range of possible albedo values ​​is covered by known space objects. Let's say the Earth reflects about 30% of the sun's rays, mainly due to clouds, and the continuous cloud cover of Venus reflects 77% of the light. Our Moon is one of the darkest bodies, reflecting on average about 11% of light, and its visible hemisphere, due to the presence of vast dark “seas,” reflects light even worse - less than 7%. But there are also even darker objects - for example, asteroid 253 Matilda with its albedo of 4%. On the other hand, there are surprisingly bright bodies: Saturn's moon Enceladus reflects 81% of visible light, and its geometric albedo is simply fantastic - 138%, i.e. it is brighter than a perfectly white disk of the same cross-section. It's even difficult to understand how he manages to do this. Pure snow on Earth reflects light even worse; What kind of snow lies on the surface of small and cute Enceladus?

Heat balance

The temperature of any body is determined by the balance between the influx of heat to it and its loss. There are three known mechanisms of heat exchange: radiation, conduction and convection. The last two processes require direct contact with the environment, therefore, in the vacuum of space, the first mechanism, radiation, becomes the most important and, in fact, the only one. This creates considerable problems for space technology designers. They have to take into account several heat sources: the Sun, the planet (especially in low orbits) and the internal components of the spacecraft itself. And there is only one way to release heat - radiation from the surface of the device. To maintain the balance of heat flows, space technology designers regulate the effective albedo of the device using screen-vacuum insulation and radiators. When such a system fails, conditions in the spacecraft can become very uncomfortable, as the story of the Apollo 13 expedition to the Moon reminds us.

But this problem was first encountered in the first third of the 20th century. creators of high-altitude balloons - the so-called stratospheric balloons. In those years, they did not yet know how to create complex thermal control systems for a sealed nacelle, so they limited themselves to simply selecting the albedo of its outer surface. How sensitive a body's temperature is to its albedo is revealed by the history of the first flights into the stratosphere. Swiss Auguste Piccard painted the nacelle of his FNRS-1 stratospheric balloon on one side white and on the other black. It was supposed to regulate the temperature in the gondola by turning the sphere one way or another towards the Sun: for this purpose, a propeller was installed outside. But the device did not work, the sun was shining from the “black” side, and the internal temperature on the first flight rose to +38°C. On the next flight, the entire capsule was simply coated with silver paint to reflect the sun's rays. It became minus 16°C inside.

American stratospheric balloon designers Explorer They took Picard's experience into account and adopted a compromise option: they painted the upper part of the capsule white and the lower part black. The idea was that the upper half of the sphere would reflect solar radiation, while the lower half would absorb heat from the Earth. This option turned out to be good, but also not ideal: during the flights in the capsule it was +5°C.

Soviet stratonauts simply insulated the aluminum capsules with a layer of felt. As practice has shown, this decision was the most successful. Internal heat, mainly generated by the crew, was sufficient to maintain a stable temperature.

But if the planet does not have its own powerful heat sources, then the albedo value is very important for its climate. For example, our planet absorbs 70% of the sunlight falling on it, processing it into its own infrared radiation, supporting the water cycle in nature, storing it as a result of photosynthesis in biomass, oil, coal, and gas. The moon absorbs almost all of the sunlight, “mediocrely” turning it into high-entropy infrared radiation and thereby maintaining its rather high temperature. But Enceladus, with its perfectly white surface, proudly repels almost all sunlight, for which it pays with a monstrously low surface temperature: on average about −200°C, and in some places up to −240°C. However, this satellite - “all in white” - does not suffer much from the external cold, since it has an alternative source of energy - the tidal gravitational influence of its neighbor Saturn (Chapter 6), which maintains its subglacial ocean in a liquid state. But the terrestrial planets have very weak internal heat sources, so the temperature of their solid surface largely depends on the properties of the atmosphere - on its ability, on the one hand, to reflect part of the sun's rays back into space, and on the other, to retain the energy of radiation passing through atmosphere to the surface of the planet.

Greenhouse effect and planetary climate

Depending on how far the planet is from the Sun and what proportion of sunlight it absorbs, temperature conditions on the surface of the planet and its climate are formed. What does the spectrum of any self-luminous body, such as a star, look like? In most cases, the spectrum of a star is a “single-humped”, almost Planck curve, in which the position of the maximum depends on the temperature of the star’s surface. Unlike a star, the planet’s spectrum has two “humps”: it reflects part of the starlight in the optical range, and the other part absorbs and re-radiates in the infrared range. The relative area under these two humps is precisely determined by the degree of light reflection, that is, albedo.

Let's look at the two planets closest to us - Mercury and Venus. At first glance, the situation is paradoxical. Venus reflects almost 80% of sunlight and only absorbs about 20%, while Mercury reflects almost nothing and absorbs everything. In addition, Venus is further from the Sun than Mercury; 3.4 times less sunlight falls per unit of its cloud surface. Taking into account differences in albedo, each square meter of Mercury's solid surface receives almost 16 times more solar heat than the same area on Venus. And yet, on the entire solid surface of Venus there are hellish conditions - enormous temperatures (tin and lead melt!), and Mercury is cooler! At the poles there is Antarctic cold, and at the equator the average temperature is +67°C. Of course, during the day the surface of Mercury heats up to 430°C, and at night it cools down to −170°C. But already at a depth of 1.5–2 meters, daily fluctuations are smoothed out, and we can talk about an average surface temperature of +67°C. It’s hot, of course, but you can live. And in the middle latitudes of Mercury there is generally room temperature.

What's the matter? Why is Mercury, which is close to the Sun and readily absorbs its rays, heated to room temperature, while Venus, which is farther from the Sun and actively reflects its rays, is as hot as a furnace? How will physics explain this?

The Earth's atmosphere is almost transparent: it transmits 80% of incoming sunlight. The air cannot “escape” into space as a result of convection - the planet does not let it go. This means that it can only cool in the form of infrared radiation. And if infrared radiation remains locked, then it heats those layers of the atmosphere that do not release it. These layers themselves become a source of heat and partially direct it back to the surface. Some of the radiation goes into space, but the bulk of it returns to the surface of the Earth and heats it until thermodynamic equilibrium is established. How is it installed?

The temperature rises, and the maximum in the spectrum shifts (Wien’s law) until it finds a “transparency window” in the atmosphere, through which IR rays will escape into space. The balance of heat flows is established, but at a higher temperature than it would be in the absence of an atmosphere. This is the greenhouse effect.

In our lives, we quite often encounter the greenhouse effect. And not only in the form of a garden greenhouse or a thick fur coat, which is worn on a frosty day to keep warm (although the fur coat itself does not emit, but only retains heat). These examples do not demonstrate a pure greenhouse effect, since both radiative and convective heat removal are reduced in them. Much closer to the described effect is the example of a clear frosty night. When the air is dry and the sky is cloudless (for example, in a desert), after sunset the earth quickly cools, and moist air and clouds smooth out daily temperature fluctuations. Unfortunately, this effect is well known to astronomers: clear starry nights can be especially cold, which makes working at the telescope very uncomfortable. Returning to Fig. 4.8, we will see the reason: it is steam s water in the atmosphere serves as the main obstacle to heat-carrying infrared radiation.

The Moon has no atmosphere, which means there is no greenhouse effect. On its surface, thermodynamic equilibrium is established explicitly; there is no exchange of radiation between the atmosphere and the solid surface. Mars has a thin atmosphere, but its greenhouse effect still adds 8°C. And it adds almost 40°C to the Earth. If our planet did not have such a dense atmosphere, the Earth's temperature would be 40° lower. Today it averages +15°C around the globe, but it would be −25°C. All the oceans would freeze, the surface of the Earth would become white with snow, the albedo would increase and the temperature would drop even lower. In general - a terrible thing! It’s good that the greenhouse effect in our atmosphere works and warms us. And it works even more strongly on Venus - it raises the average Venusian temperature by more than 500°C.

Surface of planets

Until now, we have not begun a detailed study of other planets, mainly limiting ourselves to observing their surface. How important is information about the appearance of the planet for science? What valuable information can an image of its surface tell us? If it is a gas planet, like Saturn or Jupiter, or solid, but covered with a dense layer of clouds, like Venus, then we see only the upper cloud layer and, therefore, have almost no information about the planet itself. The cloudy atmosphere, as geologists say, is a super-young surface: today it is like this, but tomorrow it will be different (or not tomorrow, but in 1000 years, which is only a moment in the life of the planet).

The Great Red Spot on Jupiter or two planetary cyclones on Venus have been observed for 300 years, but tell us only about some general properties of the modern dynamics of their atmospheres. Our descendants, looking at these planets, will see a completely different picture, and we will never know what picture our ancestors could have seen. Thus, looking from the outside at planets with dense atmospheres, we cannot judge their past, since we see only a changeable cloud layer. A completely different matter is the Moon or Mercury, the surfaces of which retain traces of meteorite bombardments and geological processes that have occurred over the past billions of years.

And such bombardments of giant planets leave virtually no traces. One of these events occurred at the end of the twentieth century right before the eyes of astronomers. It's about a comet Shoemaker-Levi-9. In 1993, near Jupiter a strange chain of two dozen small comets was spotted. The calculation showed that these are fragments of one comet that flew near Jupiter in 1992 and was torn apart by the tidal effect of its powerful gravitational field. Astronomers did not see the actual episode of the comet’s disintegration, but only caught the moment when the chain of cometary fragments moved away from Jupiter like a “locomotive.” If the disintegration had not occurred, then the comet, having approached Jupiter along a hyperbolic trajectory, would have gone into the distance along the second branch of the hyperbola and, most likely, would never have approached Jupiter again. But the comet’s body could not withstand the tidal stress and collapsed, and the energy expended on deformation and rupture of the comet’s body reduced the kinetic energy of its orbital motion, transferring the fragments from a hyperbolic orbit to an elliptical one, closed around Jupiter. The orbital distance at the pericenter turned out to be less than the radius of Jupiter, and in 1994 the fragments crashed into the planet one after another.

The incident was huge. Each “shard” of the cometary nucleus is an ice block 1–1.5 km in size. They took turns flying into the atmosphere of the giant planet at a speed of 60 km/s (the second escape velocity for Jupiter), having a specific kinetic energy of (60/11) 2 = 30 times greater than if it were a collision with the Earth. Astronomers watched with great interest the cosmic catastrophe on Jupiter from the safety of Earth. Unfortunately, fragments of the comet hit Jupiter from the side that was not visible from Earth at that moment. Fortunately, just at that time the Galileo space probe was on its way to Jupiter; it saw these episodes and showed them to us. Due to the rapid daily rotation of Jupiter, the collision areas within a few hours became accessible to both ground-based telescopes and, what is especially valuable, near-Earth telescopes, such as the Hubble Space Telescope. This was very useful, since each block, crashing into the atmosphere of Jupiter, caused a colossal explosion, destroying the upper cloud layer and creating a window of visibility deep into the Jovian atmosphere for some time. So, thanks to the comet bombardment, we were able to look there for a short time. But two months passed - and no traces remained on the cloudy surface: the clouds covered all the windows, as if nothing had happened.

Another thing - Earth. On our planet, meteorite scars remain for a long time. Here is the most popular meteorite crater with a diameter of about 1 km and an age of about 50 thousand years (Fig. 4.15). It is still clearly visible. But craters formed more than 200 million years ago can only be found using subtle geological techniques. They are not visible from above.

By the way, there is a fairly reliable relationship between the size of a large meteorite that fell to Earth and the diameter of the crater it formed - 1:20. A kilometer-diameter crater in Arizona was formed by the impact of a small asteroid with a diameter of about 50 m. And in ancient times, larger “projectiles” - both kilometer-long and even ten-kilometer-long - hit the Earth. We know today about 200 large craters; they are called astroblemes(“heavenly wounds”) and several new ones are discovered every year. The largest, with a diameter of 300 km, was found in southern Africa, its age is about 2 billion years. The largest crater in Russia is Popigai in Yakutia, with a diameter of 100 km. Larger ones are also known, for example the South African Vredefort crater with a diameter of about 300 km or the yet unexplored crater of Wilkes Land under the Antarctic ice sheet, the diameter of which is estimated at 500 km. It was identified using radar and gravimetric measurements.

On a surface Moon, where there is no wind or rain, where there are no tectonic processes, meteorite craters persist for billions of years. Looking at the Moon through a telescope, we read the history of cosmic bombardment. On the reverse side there is a picture even more useful for science. It seems that, for some reason, no particularly large bodies ever fell there, or, when falling, they could not break through the lunar crust, which on the back side is twice as thick as on the visible side. Therefore, the flowing lava did not fill large craters and did not hide historical details. On any patch of the lunar surface there is a meteorite crater, large or small, and there are so many of them that younger ones destroy those that formed earlier. Saturation has occurred: the Moon can no longer become more cratenated than it is; there are craters everywhere. And this is a wonderful chronicle of the history of the Solar System: it identifies several episodes of active crater formation, including the era of heavy meteorite bombardment (4.1–3.8 billion years ago), which left traces on the surface of all terrestrial planets and many satellites. Why streams of meteorites fell on the planets in that era, we still have to understand. New data are needed on the structure of the lunar interior and the composition of matter at different depths, and not just on the surface from which samples have so far been collected.

Mercury outwardly similar to the Moon, because, like it, it is devoid of an atmosphere. Its rocky surface, not subject to gas and water erosion, retains traces of meteorite bombardment for a long time. Among the terrestrial planets, Mercury contains the oldest geological traces, dating back about 4 billion years. But on the surface of Mercury there are no large seas filled with dark solidified lava and similar to the lunar seas, although there are no fewer large impact craters there than on the Moon.

Mercury is about one and a half times the size of the Moon, but its mass is 4.5 times greater than the Moon. The fact is that the Moon is almost entirely a rocky body, while Mercury has a huge metallic core, apparently consisting mainly of iron and nickel. The radius of the core is about 75% of the radius of the planet (for the Earth it is only 55%), the volume is 45% of the volume of the planet (for the Earth it is 17%). Therefore, the average density of Mercury (5.4 g/cm 3 ) is almost equal to the average density of the Earth (5.5 g/cm 3 ) and significantly exceeds the average density of the Moon (3.3 g/cm 3 ). Having a large metallic core, Mercury could surpass the Earth in its average density if not for the low gravity on its surface. Having a mass of only 5.5% of the Earth's, it has almost three times less gravity, which is not able to compact its interior as much as the interior of the Earth has compacted, even the silicate mantle of which has a density of about 5 g/cm 3 .

Mercury is difficult to study because it moves close to the Sun. To launch an interplanetary apparatus from the Earth towards it, it must be strongly slowed down, that is, accelerated in the direction opposite to the orbital motion of the Earth: only then will it begin to “fall” towards the Sun. It is impossible to do this immediately using a rocket. Therefore, in the two flights to Mercury carried out so far, gravitational maneuvers in the field of the Earth, Venus and Mercury itself were used to decelerate the space probe and transfer it to Mercury's orbit.

Mariner 10 (NASA) first went to Mercury in 1973. It first approached Venus, slowed down in its gravitational field, and then passed close to Mercury three times in 1974–1975. Since all three encounters took place in the same region of the planet's orbit, and its daily rotation is synchronized with the orbital one, all three times the probe photographed the same hemisphere of Mercury, illuminated by the Sun.

There were no flights to Mercury for the next few decades. And only in 2004 was it possible to launch the second device - MESSENGER ( Mercury Surface, Space Environment, Geochemistry, and Ranging; NASA). Having carried out several gravitational maneuvers near the Earth, Venus (twice) and Mercury (three times), the probe entered orbit around Mercury in 2011 and conducted research of the planet for 4 years.

Working near Mercury is complicated by the fact that the planet is on average 2.6 times closer to the Sun than the Earth, so the flow of solar rays there is almost 7 times greater. Without a special “solar umbrella,” the probe’s electronics would overheat. The third expedition to Mercury, called BepiColombo, Europeans and Japanese take part in it. The launch is scheduled for autumn 2018. Two probes will fly at once, which will enter orbit around Mercury at the end of 2025 after a flyby near Earth, two flybys near Venus and six near Mercury. In addition to a detailed study of the surface of the planet and its gravitational field, a detailed study of the magnetosphere and magnetic field of Mercury, which poses a mystery to scientists, is planned. Although Mercury rotates very slowly, and its metallic core should have cooled and hardened long ago, the planet has a dipole magnetic field that is 100 times weaker than Earth's, but still maintains a magnetosphere around the planet. The modern theory of magnetic field generation in celestial bodies, the so-called theory of turbulent dynamo, requires the presence in the interior of the planet of a layer of liquid conductor of electricity (for the Earth this is the outer part of the iron core) and relatively rapid rotation. For what reason Mercury's core still remains liquid is not yet clear.

Mercury has an amazing feature that no other planet has. The movement of Mercury in its orbit around the Sun and its rotation around its axis are clearly synchronized with each other: during two orbital periods it makes three revolutions around its axis. Generally speaking, astronomers have been familiar with synchronous motion for a long time: our Moon synchronously rotates around its axis and revolves around the Earth, the periods of these two movements are the same, i.e. they are in a 1:1 ratio. And other planets have some satellites that exhibit the same feature. This is the result of the tidal effect.

To follow the movement of Mercury, we place an arrow on its surface (Fig. 4.20). It can be seen that in one revolution around the Sun, i.e. in one Mercury year, the planet rotated around its axis exactly one and a half times. During this time, day in the area of ​​the arrow turned into night, and half of the sunny day passed. Another annual revolution - and daylight begins again in the area of ​​the arrow, one solar day has expired. Thus, on Mercury, a solar day lasts two Mercury years.

We will talk in detail about tides in Chapter 6. It was as a result of tidal influence from the Earth that the Moon synchronized its two movements - axial rotation and orbital rotation. The Earth greatly influences the Moon: it stretches its figure and stabilizes its rotation. The Moon's orbit is close to circular, so the Moon moves along it at an almost constant speed at an almost constant distance from the Earth (we discussed the extent of this "almost" in Chapter 1). Therefore, the tidal effect varies slightly and controls the rotation of the Moon along its entire orbit, leading to a 1:1 resonance.

Unlike the Moon, Mercury moves around the Sun in a substantially elliptical orbit, sometimes approaching the luminary, sometimes moving away from it. When it is far away, near the aphelion of the orbit, the tidal influence of the Sun weakens, since it depends on distance as 1/ R 3. When Mercury approaches the Sun, the tides are much stronger, so only in the perihelion region does Mercury effectively synchronize its two movements - diurnal and orbital. Kepler's second law states that the angular velocity of orbital motion is maximum at the perihelion point. It is there that “tidal capture” and synchronization of the angular velocities of Mercury - daily and orbital - occur. At the perihelion point they are exactly equal to each other. Moving further, Mercury almost ceases to feel the tidal influence of the Sun and maintains its angular velocity of rotation, gradually reducing the angular velocity of orbital motion. Therefore, in one orbital period it manages to make one and a half daily revolutions and again falls into the clutches of the tidal effect. Very simple and beautiful physics.

The surface of Mercury is almost indistinguishable from the moon. Even professional astronomers, when the first detailed photographs of Mercury appeared, showed them to each other and asked: “Well, guess, is this the Moon or Mercury?” It’s really difficult to guess: both there and there are surfaces pockmarked by meteorites. But, of course, there are features. Although there are no large lava seas on Mercury, its surface is heterogeneous: there are older and younger areas (the basis for this is the count of meteorite craters). Mercury also differs from the Moon in the presence of characteristic ledges and folds on the surface, which arose as a result of the compression of the planet as its huge metal core cooled.

Temperature differences on the surface of Mercury are greater than on the Moon: during the daytime at the equator +430°C, and at night −173°C. But Mercury’s soil serves as a good heat insulator, so at a depth of about 1 m daily (or biannual?) temperature changes are no longer felt. So if you fly to Mercury, the first thing you need to do is dig a dugout. It will be about +70°C at the equator: a bit hot. But in the region of the geographic poles in the dugout it will be about −70°C. So you can easily find a geographic latitude at which you will be comfortable in the dugout.

The lowest temperatures are observed at the bottom of polar craters, where the sun's rays never reach. It was there that deposits of water ice were discovered, which had previously been “groped” by radars from the Earth, and then confirmed by the instruments of the MESSENGER space probe. The origin of this ice is still debated. Its sources can be both comets and steam emanating from the bowels of the planet. s water.

Mercury has color, although to the eye it looks dark gray. But if you increase the color contrast (as in Fig. 4.23), then the planet takes on a beautiful and mysterious appearance.

Mercury has one of the largest impact craters in the Solar System - Heat Planum ( Caloris Basin) with a diameter of 1550 km. This is the impact of an asteroid with a diameter of at least 100 km, which almost split the small planet. It happened around 3.8 billion years ago, during the period of the so-called “late heavy bombardment” ( Late Heavy Bombardment), when, for reasons that are not fully understood, the number of asteroids and comets in orbits intersecting the orbits of terrestrial planets increased.

When Mariner 10 photographed the Heat Plane in 1974, we did not yet know what happened on the opposite side of Mercury after this terrible impact. It is clear that if the ball is hit, sound and surface waves are excited, which propagate symmetrically, pass through the “equator” and gather at the antipodeal point, diametrically opposite to the point of impact. The disturbance there contracts to a point, and the amplitude of seismic vibrations rapidly increases. This is similar to the way cattle drivers crack their whip: the energy and momentum of the wave is essentially conserved, but the thickness of the whip tends to zero, so the vibration speed increases and becomes supersonic. It was expected that in the region of Mercury opposite the basin Caloris, there will be a picture of incredible destruction. In general, it almost turned out that way: there was a vast hilly area with a corrugated surface, although I expected there to be an antipodean crater. It seemed to me that when the seismic wave collapses, a phenomenon “mirror” to the fall of an asteroid will occur. We observe this when a drop falls on a calm surface of water: first it creates a small depression, and then the water rushes back and throws a small new drop upward. This did not happen on Mercury, and we now understand why: its interior turned out to be heterogeneous, and precise focusing of the waves did not occur.

In general, the relief of Mercury is smoother than that of the Moon. For example, the walls of Mercury's craters are not so high. The reason for this is probably Mercury's greater gravity and warmer, softer interior.

Venus- the second planet from the Sun and the most mysterious of the terrestrial planets. It is not clear what the origin of its very dense atmosphere, consisting almost entirely of carbon dioxide (96.5%) and nitrogen (3.5%) and providing a powerful greenhouse effect, is. It is not clear why Venus rotates so slowly around its axis - 244 times slower than the Earth, and also in the opposite direction. At the same time, the massive atmosphere of Venus, or rather its cloud layer, flies around the planet in four Earth days. This phenomenon is called superrotation atmosphere. At the same time, the atmosphere rubs against the surface of the planet and should have slowed down long ago, because it cannot move for a long time around a planet whose solid body practically stands still. But the atmosphere rotates, and even in the direction opposite to the rotation of the planet itself. It is clear that friction with the surface dissipates the energy of the atmosphere, and its angular momentum is transferred to the body of the planet. This means that there is an influx of energy (obviously solar), due to which the heat engine operates. Question: how is this machine implemented? How is the energy of the Sun transformed into the movement of the Venusian atmosphere?

Due to the slow rotation of Venus, the Coriolis forces on it are weaker than on Earth, so atmospheric cyclones there are less compact. In fact, there are only two of them: one in the northern hemisphere, the other in the southern hemisphere. Each of them “winds” from the equator to its own pole.

The upper layers of the Venusian atmosphere were studied in detail by flybys (in the process of a gravitational maneuver) and orbital probes - American, Soviet, European and Japanese. Soviet engineers launched Venera series devices there for several decades, and this was our most successful breakthrough in the field of planetary exploration. The main task was to land the descent module on the surface to see what was there under the clouds.

The designers of the first probes, like the authors of science fiction works of those years, were guided by the results of optical and radio astronomical observations, from which it followed that Venus is a warmer analogue of our planet. That is why in the middle of the 20th century. all science fiction writers - from Belyaev, Kazantsev and Strugatsky to Lem, Bradbury and Heinlein - presented Venus as an inhospitable (hot, swampy, with a poisonous atmosphere), but generally similar to the Earth world. For the same reason, the first landing vehicles of the Venus probes were not very durable, unable to withstand high pressure. And they died, descending into the atmosphere, one after another. Then their hulls began to be made stronger, with the expectation of a pressure of 20 atmospheres, but this turned out to be not enough. Then the designers, “biting the bit,” created a titanium probe that can withstand pressure of 180 atm. And he landed safely on the surface (“Venera-7”, 1970). Note that not every submarine can withstand such pressure, which prevails at a depth of about 2 km in the ocean. It turned out that the pressure on the surface of Venus does not drop below 92 atm (9.3 MPa, 93 bar), and the temperature is 464°C.

The dream of a hospitable Venus, similar to the Earth of the Carboniferous period, was finally ended precisely in 1970. For the first time, a device designed for such hellish conditions (“Venera-8”) successfully descended and worked on the surface in 1972. From this moment of landing going to the surface of Venus has become a routine operation, but it is not possible to work there for a long time: after 1–2 hours the inside of the device heats up and the electronics fail.

The first artificial satellites appeared near Venus in 1975 (“Venera-9 and -10”). In general, the work on the surface of Venus by the Venera-9...-14 descent vehicles (1975–1981) turned out to be extremely successful, studying both the atmosphere and the surface of the planet at the landing site, even managing to take soil samples and determine its chemical composition and mechanical properties. But the greatest effect among fans of astronomy and cosmonautics was caused by the photo panoramas of the landing sites they transmitted, first in black and white, and later in color. By the way, the Venusian sky is orange when viewed from the surface. Beautiful! Until now (2017), these images remain the only ones and are of great interest to planetary scientists. They continue to be processed and new parts are found on them from time to time.

American astronautics also made a significant contribution to the study of Venus in those years. The Mariner 5 and 10 flybys studied the upper layers of the atmosphere. Pioneer Venera 1 (1978) became the first American satellite of Venus and carried out radar measurements. And “Pioneer-Venera-2” (1978) sent 4 descent vehicles into the planet’s atmosphere: one large (315 kg) with a parachute to the equatorial region of the daytime hemisphere and three small (90 kg each) without parachutes - to mid-latitudes and at the north of the day hemisphere, as well as the night hemisphere. None of them were designed to work on the surface, but one of the small devices landed safely (without a parachute!) and worked on the surface for more than an hour. This case allows you to feel how high the density of the atmosphere is near the surface of Venus. The atmosphere of Venus is almost 100 times more massive than the Earth's, and its density at the surface is 67 kg/m 3, which is 55 times denser than Earth's air and only 15 times less dense than liquid water.

It was not easy to create durable scientific probes that could withstand the pressure of the Venusian atmosphere, the same as at a kilometer depth in the Earth's oceans. But it was even more difficult to make them withstand the ambient temperature (+464°C) in such dense air. The heat flow through the body is colossal, so even the most reliable devices worked for no more than two hours. In order to quickly descend to the surface and prolong the work there, the Venus dropped its parachute during landing and continued its descent, slowed down only by a small shield on its hull. The impact on the surface was softened by a special damping device - a landing support. The design turned out to be so successful that Venera 9 landed on a slope with an inclination of 35° without any problems and worked normally.

Such panoramas of Venus (Fig. 4.27) were published immediately after their receipt. Here you can notice a curious event. During descent, each chamber was protected by a polyurethane cover, which, after landing, was shot off and fell down. In the top photo, this white semi-circular cover is visible at the landing support. Where is she in the bottom photo? Lies to the left of center. It was into it that, straightening up, the device for measuring the mechanical properties of soil stuck its probe. After measuring its hardness, he confirmed that it was polyurethane. The device, so to speak, was tested in field conditions. The probability of this sad event was close to zero, but it happened!

Given Venus's high albedo and colossal density of its atmosphere, scientists doubted there would be enough sunlight near the surface to photograph. In addition, a dense fog could well be hanging at the bottom of the gas ocean of Venus, scattering sunlight and preventing a contrast image from being obtained. Therefore, the first landing vehicles were equipped with halogen mercury lamps to illuminate the soil and create light contrast. But it turned out that there is quite enough natural light there: it is as light on Venus as on a cloudy day on Earth. And the contrast in natural light is also quite acceptable.

In October 1975, the Venera-9 and -10 landing vehicles, through their orbital blocks, transmitted to Earth the first ever photographs of the surface of another planet (if we do not take into account the Moon). At first glance, the perspective in these panoramas looks strangely distorted: the reason is the rotation of the shooting direction. These images were taken by a telephotometer (optomechanical scanner), the “look” of which slowly moved from the horizon under the “legs” of the lander and then to the other horizon: a 180° scan was obtained. Two telephotometers on opposite sides of the device were supposed to provide a complete panorama. But the lens caps did not always open. For example, on “Venera-11 and -12” none of the four opened.

One of the most beautiful experiments in the study of Venus was carried out using the VeGa-1 and -2 probes (1985). Their name stands for “Venus - Halley”, because after the separation of the descent modules aimed at the surface of Venus, the flight parts of the probes went to explore the nucleus of Comet Halley and for the first time did so successfully. The landing vehicles were also not entirely ordinary: the main part of the device landed on the surface, and during descent, a balloon made by French engineers was separated from it, which flew for about two days in the atmosphere of Venus at an altitude of 53–55 km, transmitting data on temperature and pressure to Earth , illumination and visibility in clouds. Thanks to the powerful wind blowing at this altitude at a speed of 250 km/h, the balloons managed to fly around a significant part of the planet.

Photographs from the landing sites show only small areas of the Venusian surface. Is it possible to see all of Venus through the clouds? Can! The radar sees through the clouds. Two Soviet satellites with side-looking radars and one American flew to Venus. Based on their observations, radio maps of Venus were compiled with very high resolution. It is difficult to demonstrate on a general map, but on individual map fragments it is clearly visible. The colors on the radio maps show the levels: light blue and dark blue are lowlands; If Venus had water, it would be oceans. But liquid water cannot exist on Venus, and there is practically no gaseous water there. The greenish and yellowish areas are continents (let's call them that). Red and white are the highest points on Venus, this is the Venusian “Tibet” - the highest plateau. The highest peak on it - Mount Maxwell - rises 11 km.

Venus is volcanically active, more active than today's Earth. This is not entirely clear. A famous geologist, academician Nikolai Leontyevich Dobretsov works in Novosibirsk; he has an interesting theory about the evolution of the Earth and Venus (“Venus as a possible future of the Earth”, “First-hand Science” No. 3 (69), 2016).

There are no reliable facts about the interior of Venus, about its internal structure, since seismic research has not yet been carried out there. In addition, the slow rotation of the planet does not allow measuring its moment of inertia, which could tell us about the distribution of density with depth. So far, theoretical ideas are based on the similarity of Venus with the Earth, and the apparent absence of plate tectonics on Venus is explained by the absence of water on it, which on Earth serves as a “lubricant”, allowing the plates to slide and dive under each other. Coupled with the high surface temperature, this leads to a slowdown or even complete absence of convection in the body of Venus, reduces the cooling rate of its interior and may explain its lack of a magnetic field. All this looks logical, but requires experimental verification.

By the way, about Earth. I will not discuss the third planet from the Sun in detail, since I am not a geologist. In addition, each of us has a general idea of ​​the Earth, even based on school knowledge. But in connection with the study of other planets, I note that we do not fully understand the interior of our own planet. Almost every year there are major discoveries in geology, sometimes even new layers are discovered in the bowels of the Earth, but we still do not accurately know the temperature in the core of our planet. Look at the latest reviews: some authors believe that the temperature at the boundary of the inner core is about 5000 K, while others believe that it is more than 6300 K. These are the results of theoretical calculations, which include not entirely reliable parameters that describe the properties of matter at a temperature of thousands of kelvins and a pressure of millions bar. Until these properties are reliably studied in the laboratory, we will not receive accurate knowledge about the interior of the Earth.

The uniqueness of the Earth among similar planets lies in the presence of a magnetic field and liquid water on the surface, and the second, apparently, is a consequence of the first: the Earth’s magnetosphere protects our atmosphere and, indirectly, the hydrosphere from solar wind flows. To generate a magnetic field, as it now appears, in the interior of the planet there must be a liquid electrically conductive layer, covered by convective motion, and rapid daily rotation, providing the Coriolis force. Only under these conditions does the dynamo mechanism turn on, enhancing the magnetic field. Venus barely rotates, so it has no magnetic field. The iron core of little Mars has long cooled and hardened, so it also lacks a magnetic field. Mercury, it would seem, rotates very slowly and should have cooled down before Mars, but it has a quite noticeable dipole magnetic field with a strength 100 times weaker than the Earth’s. Paradox! The tidal influence of the Sun is now believed to be responsible for maintaining Mercury's iron core in a molten state. Billions of years will pass, the iron core of the Earth will cool and harden, depriving our planet of magnetic protection from the solar wind. And the only rocky planet with a magnetic field will remain, oddly enough, Mercury.

From the point of view of an earthly observer, at the moment of opposition, Mars appears on one side of the Earth, and the Sun on the other. It is clear that it is at these moments that the Earth and Mars approach the minimum distance, Mars is visible in the sky all night and is well illuminated by the Sun. Earth takes one year to orbit the Sun, and Mars takes 1.88 years, so the average time between oppositions is just over two years. The last opposition of Mars was observed in 2016, although it was not particularly close. Mars's orbit is noticeably elliptical, so Earth's closest approaches to Mars occur when Mars is near the perihelion of its orbit. On Earth (in our era) this is the end of August. Therefore, the August and September confrontations are called “great”; At these moments, which occur once every 15–17 years, our planets come closer to each other by less than 60 million km. This will happen in 2018. And a super close confrontation took place in 2003: then Mars was only 55.8 million km away. In this regard, a new term was born - “the greatest oppositions of Mars”: these are now considered approaches of less than 56 million km. They occur 1-2 times per century, but in the current century there will be even three of them - wait for 2050 and 2082.

But even during moments of great confrontation, little is visible on Mars through a telescope from Earth. Here (Fig. 4.37) is a drawing of an astronomer looking at Mars through a telescope. An untrained person will look and be disappointed - he will not see anything at all, just a small pink “drop,” but the experienced eye of an astronomer sees more through the same telescope. Astronomers noticed the polar cap a long time ago, centuries ago. And also dark and light areas. The dark ones were traditionally called seas, and the light ones - continents.

Increased interest in Mars arose during the era of the great opposition of 1877: by that time, good telescopes had already been built and astronomers had made several important discoveries. American astronomer Asaph Hall discovered the satellites of Mars Phobos and Deimos, and Italian astronomer Giovanni Schiaparelli sketched mysterious lines on the surface of the planet - Martian canals. Of course, Schiaparelli was not the first to see the canals: some of them had been noticed before him (for example, Angelo Secchi). But after Schiaparelli, this topic became dominant in the study of Mars for many years.

Observations of features on the surface of Mars, such as “channels” and “seas,” marked the beginning of a new stage in the study of this planet. Schiaparelli believed that the “seas” of Mars could indeed be bodies of water. Since the lines connecting them needed to be given a name, Schiaparelli called them "canals" ( canali), meaning sea straits, and not man-made structures. He believed that water actually flows through these channels in the polar regions during the melting of the polar caps. After the discovery of “channels” on Mars, some scientists suggested their artificial nature, which served as the basis for hypotheses about the existence of intelligent beings on Mars. But Schiaparelli himself did not consider this hypothesis scientifically substantiated, although he did not exclude the presence of life on Mars, perhaps even intelligent.

However, the idea of ​​an artificial irrigation canal system on Mars began to gain ground in other countries. This was partly due to the fact that the Italian canali was presented in English as channel(man-made waterway), and not like channel(natural sea strait). And in Russian the word “canal” means an artificial structure. The idea of ​​Martians captivated many then, and not only writers (remember H.G. Wells with his “War of the Worlds,” 1897), but also researchers. The most famous of them was Percival Lovell. This American received an excellent education at Harvard, equally mastering mathematics, astronomy and humanities. But, as the scion of a noble family, he would rather become a diplomat, writer or traveler than an astronomer. However, after reading Schiaparelli's works on canals, he became fascinated by Mars and believed in the existence of life and civilization on it. In general, he abandoned all other matters and began studying the Red Planet.

With money from his wealthy family, Lovell built an observatory and began drawing canals. Note that photography was then in its infancy, and the eye of an experienced observer is able to notice the smallest details in conditions of atmospheric turbulence, distorting images of distant objects. The maps of Martian canals created at the Lovell Observatory were the most detailed. In addition, being a good writer, Lovell wrote several interesting books - Mars and its channels (1906), Mars as the abode of life(1908), etc. Only one of them was translated into Russian even before the revolution: “Mars and life on it” (Odessa: Matezis, 1912). These books captivated an entire generation with the hope of meeting Martians. Winter - the polar cap is huge, but the canals are not visible. Summer - the cap melted, the water flowed, channels appeared. They became visible from afar, as plants grew green along the banks of the canals. Earnestly?

It should be admitted that the story of the Martian canals has never received a comprehensive explanation. There are old drawings with channels and modern photographs without them (Fig. 4.44). Where are the channels?

What was it? Astronomers' conspiracy? Mass insanity? Self-hypnosis? It is difficult to blame scientists who have given their lives to science for this. Perhaps the answer to this story lies ahead.

And today we study Mars, as a rule, not through a telescope, but with the help of interplanetary probes (although telescopes are still used for this and sometimes bring important results). The flight of probes to Mars is carried out along the most energetically favorable semi-elliptical trajectory (see Fig. 3.7 on p. 63). Using Kepler's third law, it is easy to calculate the duration of such a flight. Due to the high eccentricity of the Martian orbit, the flight time depends on the launch season. On average, a flight from Earth to Mars lasts 8–9 months.

Is it possible to send a manned expedition to Mars? This is a big and interesting topic. It would seem that all that is needed for this is a powerful launch vehicle and a convenient spaceship. No one yet has sufficiently powerful carriers, but American, Russian and Chinese engineers are working on them. There is no doubt that such a rocket will be created in the coming years by state-owned enterprises (for example, our new Angara rocket in its most powerful version) or private companies (Elon Musk - why not).

Is there a ship in which astronauts will spend many months on their way to Mars? There is no such thing yet. All existing ones (“Union”, “Shenzhou”) and even those undergoing testing ( Dragon V2, CST-100 , Orion) - very cramped and suitable only for a flight to the Moon, where it is only three days away. True, there is an idea to inflate additional rooms after takeoff. In the fall of 2016, the inflatable module was tested on the ISS and performed well.

Thus, the technical possibility of flying to Mars will soon appear. So what's the problem? In a person! In Fig. 4.45 indicates the annual dose of human exposure to background radiation in different places - at sea level, in the stratosphere, in low-Earth orbit and in outer space. The unit of measurement is the rem (biological equivalent of an x-ray). We are constantly exposed to natural radioactivity of the earth's rocks, streams of cosmic particles or artificially created radioactivity. At the Earth's surface, the background is weak: we are protected by covering the lower hemisphere, the magnetosphere and atmosphere of the planet, as well as its body. In low Earth orbit, where ISS cosmonauts work, the atmosphere no longer helps, so the background radiation increases hundreds of times. In outer space it is even several times higher. This significantly limits the duration of a person’s safe stay in space. Let us note that nuclear industry workers are prohibited from receiving more than 5 rem per year - this is almost safe for health. Cosmonauts are allowed to receive up to 10 rem per year (an acceptable level of danger), which limits the duration of their work on the ISS to one year. And a flight to Mars with a return to Earth, in the best case (if there are no powerful flares on the Sun), will lead to a dose of 80 rem, which will lead to a high probability of cancer. This is precisely the main obstacle to human flight to Mars.

Is it possible to protect astronauts from radiation? Theoretically, it is possible. On Earth, we are protected by an atmosphere whose thickness per 1 cm 2 is equivalent to a 10-meter layer of water. Light atoms better dissipate the energy of cosmic particles, so the protective layer of a spacecraft can be 5 meters thick. But even in a cramped ship, the mass of this protection will be measured in hundreds of tons. Sending such a ship to Mars is beyond the power of a modern or even promising rocket.

Well, let’s say there were volunteers willing to risk their health and go to Mars one way without radiation protection. Will they be able to work there after landing? Can they be counted on to complete the task? Remember how astronauts, after spending six months on the ISS, feel immediately after landing on the ground: they are carried out in their arms, placed on a stretcher, and for two to three weeks they are rehabilitated, restoring bone strength and muscle strength. But on Mars no one can carry them in their arms. There you will need to go out on your own and work in heavy void suits, like on the Moon: after all, the atmospheric pressure on Mars is practically zero. The suit is very heavy. On the Moon, it was relatively easy to move in it, since the gravity there is 1/6 of the Earth's, and during the three days of flight to the Moon the muscles do not have time to weaken. Astronauts will arrive on Mars after spending many months in conditions of weightlessness and radiation, and the gravity on Mars is two and a half times greater than the lunar one. In addition, on the surface of Mars itself, the radiation is almost the same as in outer space: Mars has no magnetic field, and its atmosphere is too rarefied to serve as protection. So the movie “The Martian” is fantasy, very beautiful, but unreal.

Some options for protection against radiation during interplanetary flight

How did we imagine a Martian base before? We arrived, set up laboratory modules on the surface, live and work in them. And now here’s how: we arrived, dug in, built shelters at a depth of at least 2–3 meters (this is quite reliable protection from radiation) and try to go to the surface less often and for a short time. We basically sit under the ground and control the work of the Mars rovers. Well, after all, they can be controlled from Earth, even more efficiently, cheaper and without risk to health. This is what has been done for several decades.

What robots learned about Mars is in the next lecture.

The lecture was given on June 12, 2009 at the Moscow International Open Book Festival (with the support of the Dynasty Foundation).

Anna Piotrovskaya. Good afternoon. Thank you very much for coming. My name is Anya Piotrovskaya, I am the director of the Dynasty Foundation. Since the theme of this year's festival is about the future, we thought what would the future be without science. And since science is what our foundation does - public lectures, grants, scholarships for students, graduate students, for those people who are engaged in fundamental natural sciences; We also organize public lectures and publish books. It is surprisingly pleasant that at the stand of the Moscow store all the non-fiction books that are sold are almost all books published with our support. We do public lectures, as I said, science festivals, and so on and so forth. Come to our events.

And today we are starting a cycle consisting of three lectures, the first of which is today, the second will be tomorrow, and one more on Sunday, the last day of the festival, and I am pleased to introduce Vladimir Georgievich Surdin, astronomer, candidate of physical and mathematical sciences , which will tell us about the discoveries of new planets.

Vladimir Georgievich Surdin. Thanks, yes. First of all, I apologize for the inadequate environment. It was supposed to still show the pictures in a setting appropriate to this process. The sun is bothering us, the screen is not very bright, well... Sorry.

So, since the theme of the festival is the future, I will tell you not about the future in the sense of time, but about the future in the sense of space. What spaces are opening up to us?

We live on the planet; we have no other way of existence. Until now, planets have been discovered very rarely, and all of them were unsuitable for our life. In recent years the situation has changed dramatically. Planets began to be discovered in dozens and hundreds - both in the Solar System and outside the Solar System. There is room for imagination to unfold, at least to find a place for some expeditions, at a minimum, and maybe for the expansion of our civilization - and for saving our civilization if something happens. In general, we need to keep an eye on the place: these are future springboards for humanity, at least some of them. Well, it seems so to me.

The first part of the story will, of course, be about the inner part of the Solar System, although its boundaries are expanding, and you will see that we already understand a slightly different area by the Solar System, and the concept of “planet” has expanded. But let's see what we have in this regard.

Firstly, how we imagined it - well, actually, the diagram of the solar system has not changed, right? Eight big ones... (So, the laser pointer doesn't work on this thing, it'll have to be a classic...) Eight big planets and a lot of small ones. In 2006, the nomenclature changed - you remember, there were 9 large planets, now there are only 8 of them. Why? They were divided into two classes: classical large planets like the Earth and giant planets remained under the name “planets” (although it is always necessary to specify “classical planets”, “larger than a planet”), and a group of “dwarf planets” emerged - dwarf planets, planets dwarfs, the prototype of which was the former 9th planet, Pluto, well, and several small ones were added to it, I will show them later. They are truly special, and they were right to be highlighted. But now we only have 8 large planets left. There is a suspicion that there will be bodies near the Sun, there is confidence that there will be a lot of bodies far from the Sun, and they are constantly discovered in the gaps between large planets, I will also tell you about this. All this little stuff is called “small solar system objects.”

(Voice from the hall. Vladimir Georgievich, it’s better to take a microphone: you can’t hear very well from behind.) It’s unpleasant to listen to people talking through a microphone, but in general it’s difficult, of course, to overcome this background. OK then.

Here are the big planets. They are different, and you and I live on those that belong to the group of terrestrials, similar to the Earth. Here they are four. They are all different, they are not similar to the Earth in any sense, only in the sense of size. We will talk about them, well, and about some other bodies.

It turns out that not even all of these planets have been discovered yet. Open in what sense? At least take a look. We have already seen almost all the planets from all sides; the last one remaining, closest to the Sun, is Mercury. We haven't seen it from all sides yet. And you know that there can be surprises. Let's say the far side of the Moon turned out to be completely different from the visible one. It is possible that there will be some surprises on Mercury. Spacecraft have approached it and have already flown past it three times, but they have not been able to photograph it from all sides. There remains 25 or 30 percent of the surface that has never been seen before. This will be done in the coming years, in 2011, where the satellite will already begin to operate, but for now there is still a mysterious other side of Mercury. True, it is so similar to the Moon that it makes no sense to expect any supernatural surprises.

And, of course, the small bodies of the Solar System have not yet been completely exhausted. Basically, they cluster in the space between Jupiter and Mars - the orbit of Jupiter and the orbit of Mars. This is the so-called Main Asteroid Belt. Until recently, there were thousands, and today there are hundreds of thousands of objects.

Why is this done? First of all, of course, big tools. The most royal telescope, Hubble, which operates in orbit, is the most vigilant so far, it’s good that it was fixed. There was an expedition recently, it will work for another 5 years, then it will come to an end, but it will be replaced by new space instruments. True, it is rarely used to study the Solar System: its operating time is expensive, and it, as a rule, works on very distant objects - galaxies, quasars and beyond. But, when necessary, it is deployed to the solar system.

But on the surface of the Earth, many astronomical instruments actually appeared, already completely aimed at studying the Solar System. Here is the largest observatory in the world on Mount Mauna Kea - this is an extinct volcano on the island of Hawaii, very high, more than four kilometers. It is difficult to work there, but it contains the largest astronomical instruments today.

The largest of them are these two, two brother telescopes with the diameters of the main mirrors - and this is the leading parameter... (So, this pointer is not visible.) The leading parameter of a telescope is the diameter of its mirror, since this is the light collection area; This means that the depth of the view into the Universe is determined by this parameter. These two telescopes are like two eyes, not in the sense of stereoscopy, but in the sense of image clarity, like a binocular telescope they work very well, and with their help many interesting objects have already been discovered, including in the Solar System.

See what a modern telescope is. This is the camera of a modern telescope. Only a camera of this size. The telescope itself weighs up to 1000 tons, the mirror weighs tens of tons, and the cameras are of this scale. They cool down; CCD matrices are the sensitive plate that works in our cameras today. They have approximately the same type of CCD matrix, but they are cooled to almost absolute zero, and therefore the sensitivity to light is very high.

Here is a modern CCD matrix. This is a set of approximately the same... Just like in a good household camera we have 10-12 megapixel plates, but here they form a mosaic, and in total we get a much larger light-gathering area. And, most importantly, at the moment of observation, you can immediately dump this data into a computer and compare, say, pictures received now and an hour earlier or a day earlier, and this is how we notice new objects.

The computer immediately highlights those luminous points that have moved against the background of fixed stars. If a point moves quickly, over tens of minutes or hours, it means it is not far from the Earth, and it means it is a member of the solar system. It is immediately compared with the data bank: if this is a new member of the solar system, then a discovery has been made. Over the entire 19th century, approximately 500 small planets - asteroids - were discovered. Over the entire - almost entire - 20th century, 5,000 asteroids were discovered. Today, approximately 500 new asteroids are discovered every day (or rather, every night). That is, without a computer we wouldn’t even have time to write them down in catalogues, discoveries are being made with such frequency.

Look at the statistics. Well, of course, I didn’t draw the 19th century... (I don’t know, is the pointer visible against this background? It’s bad, of course, but it’s visible.) This is how, until 2000, there was a slow quantitative growth of small bodies in the Solar System, asteroids ( well, they are not so small - tens, hundreds of kilometers in size). Since 2000, new projects, such as large telescopes, have sharply accelerated the growth, and today we have about half a million asteroids discovered in the solar system. Well, the truth is, if you put them all together and make one planet out of them, it will turn out to be slightly larger than our Moon. In general, the planet is small. But their number is gigantic, the variety of movements is enormous, we can always find asteroids close to the Earth and, accordingly, explore them.

Here is the situation near the Earth, look. This is the Earth’s orbit, here is our planet itself, a dot, and asteroids darting past it. Well, this is not in real time, of course, this situation was calculated for 2005, but look how close they fly and how often they approach the Earth. When they talk about the asteroid danger, sometimes it is exaggerated - astronomers do this in order to receive funding or for some other benefit of their own. But, in general, this danger is real, and we need to think about it, at least predict the movement of asteroids and anticipate the situation.

This is how telescopes see an asteroid moving against a background of stars. Consecutive images: firstly, during the exposure the asteroid itself moves, it appears in the form of such a line, and secondly, it clearly moves from one exposure to another. 3-4 pictures, and you can (the computer can) calculate the orbit and predict the further flight of the asteroid.

It’s not for nothing that I’m showing you this slide. Last year, for the first time in the history of science, it was possible to notice an asteroid approaching the Earth, calculate its orbit, understand that it would crash into the atmosphere (it was small, a few meters in size, there was nothing terrible), it would crash into the Earth’s atmosphere. Where exactly - on this map... actually, this is not a map, this is a picture taken from a satellite. Here we have Egypt, and here is Sudan, this is the border between them. And exactly in the place where the asteroid was expected to fall, its entry into the atmosphere, combustion and flight was observed.

This was also observed from Earth: it collapsed in the atmosphere, it was partially photographed, and they even approximately guessed the place where it would fall, and after two weeks of searching they actually found a bunch of debris, fragments, and meteorites there. For the first time, we were able to notice the approach of an asteroid and accurately guess the place where it would fall.

Now such work is done systematically; well, it’s true that there hasn’t been a second such case yet, but there will be, I’m sure. Now you can collect meteorites not by randomly wandering around the Earth and looking for where a meteorite could lie, but simply quite consciously follow the flight of an asteroid and go to that... well, it’s better to wait until it falls, and then go to that place , where the meteorite will fall out. It is very important to find fresh meteorites that are not contaminated with biological material from the Earth to see what he had there in space.

The situation with other small bodies, namely with the satellites of planets, is also changing very quickly. Here, for 1980, is the number of satellites belonging to each of the planets. On Earth, of course, their number has not changed; we still have one Moon; Mercury and Venus have no satellites at all. Mars still has two of them - Phobos and Deimos, but the giant planets, and even small Pluto, have discovered a colossal number of new satellites over the past two decades.

Jupiter's last one was discovered in 2005, and today there are 63 moons. All school textbooks no longer correspond to reality.

Saturn has 60 satellites discovered today. Of course, most of them are small, ranging in size from 5 to 100 km. But there are also very large ones: for example, Titan, this orange satellite - it is larger than the planet Mercury, that is, generally speaking, it is an independent planet, I will tell you about it today. But fate decreed that it became a satellite of Saturn, so it is considered not a planet, but a satellite.

Uranus today has 27 known satellites, Neptune has 13, and the largest of them are very interesting.

Here I posted a photo of Triton, this is Neptune’s largest satellite, and look: it has its own Antarctica, this ice cap at its south pole. Here the scale is not maintained, of course, so that you can see the details, I slightly, four times, increased the size of Triton; compared to Neptune, it is not so large. But it is the size of our Moon - in general, it is also a quite large body, and since it is far from the Sun, it holds (far from the Sun - which means cold) both ice on its surface and even a rarefied atmosphere near its surface. That is, in all respects it is a small but interesting independent planet, but it is accompanied by Neptune in its flight, there is nothing wrong with that.

And even Pluto, which today turned out to be a dwarf planet, also had its own system of satellites. In 1978, the first one was discovered in him - this one, Charon. It is almost the same size as Pluto itself, which is why today we call this pair a double planet. Their size difference is only about 4 times. Such a micro-double planet.

But with the help of the Hubble telescope in 2005, it was possible to discover two more near Pluto and Charon - if you notice, there are bright dots here - two small objects. It turned out that Pluto has not one, but three - at least three satellites.

They were given names from mythology associated with hell: Hydra and Nyx. There are still plenty of mythological names. With difficulty, really; sometimes you have to invent something, but, in general, mythology - Greek, Roman - is so vast that no matter how much you open it, there is still enough. At least enough for satellites.

Each planet is capable of keeping satellites close to it, in a limited space. For example, this is the Sun, the Earth, and this is the area that the Earth controls with its gravity - the Roche zone. The Moon moves within this region and is therefore connected to the Earth. If it were a little further from its border, it would walk like an independent planet. So, for each planet, especially the giant ones - Jupiter and Saturn - these areas, which are controlled by its own gravity, are very large, and therefore there are many satellites there, they have to be scooped out. But their nature is different, that’s a fact.

Here's a look at how Saturn's satellite system works. We took out a picture from the center; next to Saturn, all the satellites move in the same direction, in the same plane, approximately the same as the planets in the Solar System. That is, this is a small model of the solar system. It is obvious that they were all born along with the planet itself and were formed at the same time - 4.5 billion years ago. And the rest, external satellites, move chaotically, their orbits are inclined at different angles, they move along orbits in one or the other (we say forward or reverse) direction. And it is clear that these are acquired satellites, that is, they were captured from the asteroids of the Solar system. They can be captured today, lost tomorrow; This is such a changing circumplanetary population. And these, of course, are eternal, they were formed long ago and will never disappear anywhere.

In general, the process of formation of the Solar system is becoming clear gradually. This, of course, is a picture, but this is how we imagine the first hundreds of millions of years of the life of the Sun and circumsolar matter. First, large planets formed, then matter began to grow around them, attracted by gravity. Satellites and rings were formed from it; All giant planets have both rings and satellites. This process was reminiscent of the formation of the solar system itself.

That is, an area was organized inside the Solar System - the planet and its environment - which, on a small scale, followed approximately the same path in its development.

On the far reaches of the Solar System, approximately 15 years ago - already more, about 20 years ago - an area populated by very special microplanets was discovered. We now call it the Kuiper belt because 50 years ago the American astronomer Kuiper predicted its existence. Beyond the orbit of Neptune lies the orbit of Pluto, and we now understand that it is a member of a large group flying in the outer regions of the solar system. Today, several thousand objects have already been discovered there, the largest of which you can see.

Here, for the scale of the Earth and the Moon, and Pluto - by the way, this is a real image of Pluto, we don’t have anything better today, because it is far away and it’s difficult to see details, but the Hubble telescope was able to see something there. These are drawings; Of course, we do not see the surfaces of distant bodies. But look: bodies larger than Pluto have already been discovered in the Kuiper belt. For this reason, a group of dwarf planets was identified. Because Pluto is not special at all, it is a member of, probably, a large brotherhood of dwarf planets. They are independent and interesting.

These are all the drawings. Next to a scale image of the Earth, but these are all drawn pictures. How do we imagine the largest Kuiper Belt objects? It is impossible to see their surface: firstly, they are far away, and secondly, they are very poorly illuminated by the Sun, because they are far away. But note: Pluto has three moons, and Eris has at least one (already discovered), Haumea has two large moons. That is, the bodies are quite independent, complex, have systems of satellites... Apparently, they also have an atmosphere, only these atmospheres are frozen, frozen, it’s cold there. And for Pluto, which moves in an elongated orbit and sometimes approaches the Sun, you can see it here: sometimes it moves away from the Sun, and, of course, everything freezes there, ice and snow lie on the surface. Sometimes, at this point in the orbit, it approaches the Sun, and then its atmosphere, more precisely, the ice on its surface, melts, evaporates, and the planet is enveloped in its atmosphere for several decades, then again the atmosphere freezes and falls in the form of snow on the surface of the planet .

This, by the way, is a future option for the development of Earth civilization. Today bodies are cold, but someday the situation will change. Let's see what astronomers are predicting for the Earth today. We imagine modern Earth. In the past, the Earth's atmosphere was probably more saturated with gases, and even the gas composition was different. At least it was denser and more massive because gas is being lost from the Earth's atmosphere. Every second, approximately 5 kg of gas flies out of the earth's atmosphere. It seems like nonsense, but over billions of years this is quite a lot, and in three billion years we expect to see the Earth almost devoid of an atmosphere, partly also because the Sun warms the Earth more and more - well, I don’t mean today, at all The weather changes frequently, and the brightness of the Sun increases constantly. Every billion years, the heat flow from the Sun increases by approximately 8 to 10%. This is how our star evolves. In three billion years, the Sun will shine 30% brighter, and this will be fatal for the atmosphere. It will begin to evaporate very quickly, and the oceans will go with it, as air pressure will drop and the water will begin to evaporate faster. In general, the Earth will dry out. It's hard to say about temperature; Maybe the temperature won’t change much, but once it dries out, that’s for sure, it will lose its gas shell. Therefore, we need to look for some springboards for development, and distant cold planets today can become warm and favorable in billions of years.

Here is a drawing, approximately how we see the evolution of the Sun in 4.5–5 billion years. It will swell and finally destroy the Earth; it will enter the final stage of evolution. The red giant will be in the place of the Sun - a star of huge size, low temperature, but high heat flow, simply due to its large size, and the Earth will end. It is not even clear whether the Earth will survive as an individual body. It is possible that the Sun will expand up to the orbit of the Earth and absorb it, the Earth will dive into the Sun. But even if this does not happen, the biosphere will come to an end.

In general, the region in the solar system where life is possible is moving. It is usually called the “life zone,” and look: 4.5 billion years ago the life zone captured Venus, it was not very hot there, not like today, and it also captured the Earth, of course, because 4 billion years ago on Earth there was already life. As the Sun's brightness increases, the life zone moves away from it, the Earth is in the life zone today, and Mars falls into the life zone. If Mars had retained its atmosphere to this day, the temperature on it would have been comfortable, rivers would have flowed, and life could have existed. Unfortunately, at that time, until the life zone reached it, Mars had already lost its atmosphere, it weakly attracts gases, they evaporate, and today, even in a favorable situation, it is so dry that it is unlikely... That is, on there is no life on its surface, but under the surface, it is not yet excluded, perhaps.

Well, then the zone of life will move faster and faster from the Sun and will cover the giant planet. On the giant planets themselves, of course, life is unlikely, but on their satellites, as you will now see, it is very possible. We'll talk about them now.

Jupiter has many satellites. This is mostly a small thing, but the four so-called “Galilean satellites”, discovered just 400 years ago, in 1610, by Galileo, have been attracting attention for a long time. These are large independent bodies.

For example, Io is the closest large satellite to Jupiter. There are volcanoes on it.

Firstly, it is a natural color. Please note: an absolutely amazing combination of colors, rare for space. This orange, yellowish one - well, these are frozen gases, of course. But this is all a surface covered with sulfur compounds. Why is there so much of it? And here are active volcanoes. For example, a black stream of molten sulfur flows from the crater of a volcano. This is what the volcano scattered around itself. You can still find a lot: here there is an active volcano, here... about 50 active volcanoes can be seen from afar, from space. I can imagine how many of them will be found when some automatic station starts working on the surface of Io. It looks simply terrifying.

This is what the eruption of the largest volcano on Io, Mount Pele, looks like. The picture is greatly enlarged, here is the edge of the satellite, its horizon, and there, beyond the horizon, there is a volcano. You see, what he throws out of himself flies up to a height of about 300-350 km, and some of it even flies into space.

Of course, Io's surface is cold. You see that the gases here froze and lay on the surface in the form of snow. But the closer you are to the volcano, the warmer it gets. It’s like at a fire, you know, in winter, a step to the side near a fire is cold, a step towards the fire is hot, and you can always find an area where the temperature next to the fire is comfortable. An even more accurate analogy is the black smokers at the bottom of our oceans. You know: these are small volcanoes, or rather geysers, that work at the bottom of our oceans. The surrounding water is around freezing, and the water coming out of these black smokers is approximately 400 degrees Celsius. And here, on the border between boiling water and frost, life blossoms next to black smokers. It is possible that in the area around the volcanoes of Io, some form of life exists at a comfortable temperature. There was no opportunity to check it yet; no one sat there. There were only orbital ones, not even orbital ones - such fly-by research, fast ones.

The second satellite, more distant from Jupiter, is Europa. It is, of course, cooler, there are no volcanoes, and its entire surface resembles our Antarctica. This is a solid ice dome - not even a dome, but just an icy crust covering the satellite - but, judging by calculations, at a depth of several tens of kilometers under this solid ice there is liquid water. Well, we have the same situation in Antarctica: our Antarctic southern dome is icy, but at a depth of three kilometers there are lakes of liquid water; There, the heat that comes out from the bowels of the planet melts the water. The same is probably true for Europa. I would really like to dive into this ocean and see what is happening there. Where there is liquid water, there is usually life.

How to dive? These stripes that divide the ice sheet are most likely cracks. Here - these are, admittedly, highly contrasting colors, this is an unnatural color - here we look closely at them and see that there is fresh ice, it runs along the stripes. Most likely, there are times when the ice dome cracks and water rises from there. Unfortunately, we have not seen the sources yet.

This is what the ice dome of Europe looks like in real colors. There are hummocks and icebergs there, it is clear that some movements are taking place near the ice, shifts and ruptures are visible. But no one has yet been able to see a real crack so that they can look into the ocean.

In recent years, when this discovery was made, astronomers - more precisely, space specialists - began to think about how to dive there, launch a robot that might look for life forms there. The ice is thick, at least 30 kilometers, and maybe 100, the calculations here are not very accurate. The crack has not yet been found. There are projects, mostly within the framework of NASA, and we also have some people in our space institutes who are working on this. They thought about making complex devices with a nuclear energy source that would melt the ice and break through, in general, on the verge of, and perhaps beyond, technical capabilities.

But just last year it turned out that this was not necessary. A new discovery has been made that promises us great prospects. The discovery is not in the Jupiter system, but in the Saturn satellite system. Saturn also has many satellites, and pay attention: even in this picture, of course, not all are depicted; one of the satellites was not paid attention to at all.

This is Titan, the largest, and here I separately found a photograph next to Titan, where this small satellite named Enceladus is passing. It is so small, 500 km in diameter, that it was considered uninteresting by ordinary people. Now near Saturn - in orbit around Saturn - there is a good NASA spacecraft, Cassini, and it has flown up to Enceladus several times.

And what happened? A completely unexpected thing.

This is what Enceladus looks like from afar. Also an icy surface. But what immediately catches your eye - geologists immediately pay attention to this - is that it seems to consist of two halves. The northern part is covered with meteorite craters, which means that the ice is old, that meteorites have fallen on it for millions of years and have beaten it thoroughly. This is a geologically old surface. But the southern part does not contain a single crater. What, meteorites didn't fall there? It’s unlikely, they don’t fall with precision. This means that some geological process is constantly renewing the southern ice, and this immediately attracted attention. What does “renew the ice” mean? This means pouring liquid water over it and destroying the meteorite craters.

They began to look closely at the southern hemisphere of Enceladus. Indeed, we saw powerful cracks there, and you see how deep the canyon is in the ice surface.

(Well, I can’t help but regret that this audience is not dark, but completely unsuited for showing slides. It’s all very beautiful in fact. Well, okay, next time we’ll gather in a dark environment, and then you’ll see more But something is visible here too.)

And one area, literally at the south pole of Enceladus, turned out to be very interesting. There are four longitudinal stripes here. In English they began to be called “tiger stripes”, these stripes do not mean the stripes that are on the tiger’s belly or, wherever, on the back, but these are the ones that remain from the claws when the tiger pets you. And indeed, these turned out to be those same claw marks. That is, breaks on the surface.

Flying behind the satellite from the side opposite to the Sun, in backlighting, Cassini, the Cassini apparatus, saw fountains of water gushing from precisely these fractures in the ice. The most natural fountains. Of course, this is not liquid water. Liquid breaks through the cracks, through the cracks, it immediately evaporates and freezes in the form of ice crystals, because it flies out into the vacuum, and, in essence, these are streams of snow already flying, but below these are outflows of water, of course. An absolutely amazing thing.

This means that we get the material directly from the ice ocean, from the ocean of liquid water that exists under the surface of this satellite.

In artificial colors, greatly enhanced in brightness and contrast, it looks like this super-fountain that shoots straight into space, which flies into space from the surface of Enceladus. But this photograph is the orbit of Enceladus around Saturn: here is Enceladus, along its orbit it scattered its snow, steam and ice. That is, one of the rings of Saturn, the outermost ring, is essentially the material ejected by Enceladus - water vapor and ice crystals ejected by Enceladus recently.

Well, this is, of course, a fantastic drawing; astronauts are unlikely to find themselves on the surface of this satellite soon, but this is a real infrared photograph. These same four stripes are warm. The infrared instrument, the camera on board Cassini, photographed the stripes, and you see that they are warm, that is, there is liquid water underneath the ice. Here it comes straight to the surface of the ice and flies up through the cracks.

At the end of last year, Cassini’s orbit was changed so that it flew straight through these fountains, literally passing near the surface of the satellite at an altitude of 20 km and scooping up this water. And he proved that it really is H 2 O that flies out from there. Unfortunately, there are no biological laboratories on board Cassini, so he cannot analyze this water for the composition of microorganisms. No one imagined that such a discovery would occur at all. But now no one, almost no one, is interested in Europe, where the 100-kilometer ice shell needs to be drilled and drilled with who knows what. Everyone has refocused on Enceladus, from which water flies out on its own, and you just need to either fly by or land a device on the surface and analyze this substance for its biological composition.

It’s very interesting, and now there are just a lot of projects aimed at exploring Enceladus.

This is how we imagine the origin of these fountains: the subglacial ocean is watery, and water seeps through gaps in the ice and pours out into the vacuum, flies out and follows the satellite in orbit.

Of course, many planets have other interesting satellites. For example, I really like Hyperion, one of the small satellites of Saturn.

Look, it looks like a sea sponge. It is also unclear why exactly such a structure arose for him. It’s like March snow melted by the sun’s rays. You can’t keep track of everything; there aren’t enough scientific instruments and apparatus for each satellite yet. We are only examining them from afar, but the time will come - they will sit there and look.

Everything that has been discovered in recent years has been done by this wonderful device. This is the most expensive automatic interplanetary spacecraft in the history of astronautics, Cassini-Huygens. The Americans made it, but Europe also contributed... Sorry, the Americans made the main apparatus, Cassini, and they gave it a launch vehicle, Titan, but this additional apparatus, Huygens, was made by the Europeans.

This probe, the cost of the entire project is 3 billion dollars, is, indeed, at present times 10 times more than a traditional spacecraft. This thing was launched a long time ago, in 1997, and moved along a very complex trajectory, because it was a heavy apparatus and could not be immediately thrown towards Saturn. It flew from the Earth to Venus, that is, inside the solar system, then again to the Earth, then flew up to Venus again. And each time, flying past the planets, he gained a little extra speed due to their attraction. Eventually, a third flyby of Earth sent it toward Jupiter. Jupiter pushed it very hard, and the device reached Saturn in 2004. And now it has entered orbit, this is the first satellite in the history of astronautics, an artificial satellite of Saturn, and it has already been working there for almost four, five years, and very effectively.

One of the main goals of this flight was to explore Titan. Titan is, of course, an amazing satellite. I have already said: this is an independent planet.

This is how we saw Titan before Cassini got to it. It is covered with an atmosphere, the atmosphere is cold, opaque, everything is a haze, and no one knew what was there on the surface.

This is how we saw it through the atmosphere using the Huygens instruments. He has special instruments, cameras - television cameras, more precisely - which have the ability to still see the surface of the planet through a thin spectral window, where the atmosphere absorbs little. Here is Titan's Antarctica... Yes, pay attention: the atmosphere is visible, and how thick it is! It is somewhere around 500 km thick, because the planet is small - well, like small, larger than Mercury - but still the force of gravity there is small, b therefore the atmosphere stretches very far, it is not pressed to the surface of the planet.

This is a shot of the southern part of Titan. This is where frozen ice obviously lies, like our Antarctica. There were many interesting questions about both the composition of the atmosphere and the surface.

This is how we see the surface of Titan today near the South Pole. It turned out that there are lakes there - well, it’s hard to call them seas, but lakes of liquid CH 4 - methane. The temperature is low, about minus 200, so these gases are in a liquid state. But the main thing, of course, was to sit on its surface.

Here is the Huygens lander, which the Europeans made, and they made it very well. You will be surprised: it was made at Mercedes-Benz, and therefore it really worked reliably... You know, not very reliably, in fact, it worked. I don’t mean cars, but this device - there were two duplicated radio channels, but one radio channel still failed; good thing they were dubbed. Half of the information was missing, but we received half.

This is a heat shield, because at first the device goes without any braking, just at the second cosmic speed, crashes into the satellite’s atmosphere, and it is very thick and extended.

Then he throws out parachutes - one parachute, the second - and gradually lowers to the surface by parachute. He spent two hours parachuting down until he touched the surface. And while he was descending by parachute during these two hours, he took photographs, of course. Not very high quality, well, it was very difficult.

You know, I want to talk about everything, there were a lot of interesting things in this experiment, in these travels, but there is no time. Read it sometime. How many technical problems were solved literally at the last moment in order to see anything at all!

These are clouds. Now from a height of 8 km we can see the surface of Titan. Now he has already passed through the clouds; Well, here two more clouds are visible, but basically we already see a solid surface. And immediately a surprise. The solid surface has flat areas that resemble the seabed. And there are rugged areas, mountainous, and the meanders of clearly some rivers are visible on them. What flows in these rivers, what kind of liquid - maybe the same methane, most likely, or once flowed. But look: obviously, the delta, then the seabed, here is a mountain system - very similar in geography to the Earth. And in terms of atmosphere, it’s generally a copy of the Earth. The atmosphere of Titan, unlike all other planets...

Well, let's take Venus: the atmosphere there is pure CO 2, poison for us. On Mars: CO 2, carbon dioxide, poison. Let's take Titan: the atmosphere consists of molecular nitrogen. And now we have 2/3 of molecular nitrogen here. In general, for us it’s just a normal neutral environment. There is no oxygen there, of course, but the nitrogen environment is still very good. The pressure at the surface is one and a half Earth atmospheres, that is, almost the same as in this room. The temperature is a bit chilly, but that's okay. Hot is deadly for experiments, cold is even favorable, because there is no need to cool the apparatus, it will cool itself.

And so he sat down on the surface. (This is a drawing, this is not a photograph.) This little machine sat down and transmitted data about Titan to us for two hours.

This is the only television frame transmitted to her. There is the horizon, right next to the apparatus, there are cobblestones - obviously this is frozen water; at a temperature of minus 180, water is like stone, hard, and so far we know nothing more about it.

Why is he interesting? Because its gas composition and surface temperature, as biologists think, are very close to what we had on Earth four billion years ago. Perhaps by studying Titan we will be able to understand the first processes that preceded biological evolution on Earth. Therefore, it receives a lot of attention and will continue to be explored. This is the first satellite of the planet (except the Moon) on which an automatic station was landed.

Question from the audience. What about Huygens?

V. G. Surdin."Huygens" is over. The battery ran out, it worked for two hours, and that’s it. But not only. Everything there was designed so that he would work for two hours. Because he did not have enough transmitter power to communicate with the Earth, and he communicated through an orbital vehicle, but it flew away, and that’s it, the connection stopped. No, okay, I did my job.

Asteroids. Spacecraft have already approached the asteroids, and now we can already see what kind of bodies they are. There was no big surprise; this is really how we imagined asteroids: fragments, large or small, of pre-planetary bodies.

This is what asteroids look like as spacecraft fly past them, this is a series of frames, just so you can see. It is clear that they are experiencing mutual collisions.

Look at the huge crater discovered on the Stern asteroid. Sometimes the craters are so large that it is unclear how the body itself did not break upon impact.

For the first time, we recently managed to fly up and almost land on the surface of an asteroid. This asteroid here. Who do you think did this, what country?

V. G. Surdin. Well, you know... But it was completely unexpected that the Japanese did it. The Japanese somehow speak very modestly about their space research. Or rather, they don’t say.

The Japanese spacecraft, really the first interplanetary Japanese spacecraft, flew up to this asteroid with the Japanese name Itokawa - but, roughly speaking, they specially opened it for this purpose and gave it this name. A very small asteroid, measuring only 600 meters along its long axis - well, the size of the Luzhniki stadium.

This small device flew up to him and - you can see its shadow in this photograph - he photographed its shadow falling on the surface of the Itokawa asteroid.

Gradually he got closer to it (well, this is, naturally, the picture you see), did not sit on its surface, but hovered above it at about a distance of 5 or 7 meters. Unfortunately, his electronics began to malfunction... - here are the Japanese, but still his electronics began to malfunction, and then we are not entirely sure what happened to him. He was supposed to drop a small robot onto the surface - here it is drawn here - the size of... this is the size of the robot, but since the gravity on the asteroid is almost zero, this robot, pushing off with small antennae like this, had to jump on the surface. No signal was received from him - apparently, he simply did not hit the surface.

But a much more interesting experiment was done. With the help of such a vacuum cleaner - here the pipe sticks out - a soil sample was taken from the surface of this asteroid. Well, the vacuum cleaner, of course, doesn’t work there, there’s an airless space there. Therefore, he fired small metal balls at the surface, the balls caused such micro-explosions, and some of the dust from this asteroid was supposed to fall into this pipe. Then she was packed (should have been packed) into a special capsule, and the device set off towards the Earth. This experiment was specifically designed to deliver asteroid material to Earth. For the first time in history. But the engines malfunctioned, and instead of flying to the Earth a long time ago, it is now slowly, slowly rewinding revolutions around the Sun and is still gradually approaching the Earth. Maybe in a year or a year and a half, if he is still alive, he will reach Earth and bring back soil samples from the asteroid for the first time.

But soil from comets has already been obtained. Comets are remarkable because they have been frozen for billions of years. And there is hope that this is the same substance from which the Solar system was formed. Everyone dreamed of getting his samples.

The Stardust spacecraft flew up to this nucleus of comet Wild-2 in 2006. It was designed in such a way that, without landing on the surface of the comet, it was possible to take a sample of its substance.

This apparatus was attached to the tail of the comet, from the capsule, which then returned to Earth, a special trap was deployed, it is approximately the size of a tennis racket, in the form of a waffle design, and the cells between the ribs are filled with a viscous substance of a very special property - it is called “aerogel” . This is foamed glass, very finely foamed glass with argon, and its spongy, half-solid, half-gas consistency allows dust particles to get stuck in it without being destroyed.

And here, in fact, is this very matrix. And so each cell is filled with the lightest artificial substance in the world - airgel.

See what a micrograph of a speck of dust flying inside this substance looks like. Here it crashes at cosmic speed, 5 km per second, pierces this airgel and gradually slows down in it without evaporating. If she hit a hard surface, she would evaporate instantly, there would be nothing left. And when it gets stuck, it remains there in the form of a solid particle.

Then, after flying past the comet, this trap was again hidden in a capsule, and it returned to Earth. Flying past the Earth, the device dropped it by parachute.

Here in the Arizona desert they found it, this capsule, opened it, and you see how they study the composition of this trap. Microparticles were found in it. By the way, it was very difficult to find them, there was an Internet project, many people helped - volunteers, enthusiasts - helped to search for this case using microphotographs, this is a separate conversation. Found.

And immediately an unexpected discovery was made: it turned out that the solid particles that were stuck there - geologists say so - were formed at a very high temperature. But we thought that, on the contrary, the solar system and the matter of comets were always at a low temperature. Right now there is this problem: why do comets contain refractory solid particles, where did they come from? Unfortunately, it was not possible to analyze them: they are very small. Well, there will be more flights to comets, the trouble is just beginning.

By the way, they continued. The American device “Deep Impact” also flew up to one of the comet nuclei - comet Tempel-1 - and tried to click and see what was inside. A blank was dropped from it - in my opinion, about 300 kg in weight, copper - which crashed here at the speed of a satellite; This is the moment of impact. It penetrated to a depth of several tens of meters, and there it slowed down and exploded, simply from kinetic energy: it flew very quickly. And the substance ejected from inside was spectrally analyzed. So, one might say, we have already dug inside the comet nuclei. This is very important, because the crust of a comet is processed by solar rays and solar wind, but this is the first time that matter has been captured from the depths. So comet nuclei have been well studied. Today we already present them in such variety.

This is the nucleus of Comet Halley, remember, in 1986 it - well, someone should remember - flew up to us, we saw it. And these are the nuclei of other comets that spacecraft have already approached.

I said that recently... - actually, for a long time now - suspicions arose that we were missing something in the solar system. See, there's a little question mark here.

Why exactly there, near the Sun? Because astronomers find it difficult to observe areas near the Sun. The sun is blinding, and the telescope sees nothing there. The Sun itself is visible, of course, but what’s next to it? Even Mercury is very difficult to see through a telescope; we don’t know what it looks like. And what’s inside Mercury’s orbit is a complete mystery.

Recently the opportunity to look at these areas has arisen. Orbiters now take daily photographs of the surroundings of the Sun, covering the solar disk itself with a special shutter so that it does not blind the telescope. Here it is on a leg, this flap. And now we see: well, this is the solar corona and what may appear next to the Sun.

About once a week, small comets are now discovered that have approached the Sun to a distance of one or two of its own sizes. Previously, we could not discover such small comets. These are bodies 30–50 meters in size that evaporate so weakly away from the Sun that you won’t notice them. But approaching the Sun, they begin to evaporate very actively, sometimes they hit the solar surface, die, sometimes they fly past and almost completely evaporate, but now we know that there are a lot of them.

By the way. Well, since you came here, it means you are interested in astronomy. You can discover comets without a telescope, but only with a computer, which everyone has. These images are uploaded to the Internet every day, you can take them from there and see if a comet has approached the Sun. Astronomy enthusiasts do this. I know at least two boys in Russia who live in a village, they don’t have... - for some reason they have a computer with the Internet there. There is no telescope. So, they have already discovered one, in my opinion, even five comets that received his name and, in general, everything is fair. Just having this kind of persistence and working in this direction every day. Well, many people do this abroad too. So it has now become easier to discover a comet even without a telescope.

Near the Sun, between the orbits of Mercury and the surface of the Sun, there is an area where it is very possible that we will discover new small planets. They have even been given a preliminary name. Once in the 19th century, they suspected the existence of a planet there and gave it the name Vulcan, but it was not there. Now these small bodies, which have also not yet been discovered, but may be discovered in the near future, are called “volcanoids.”

And now an unexpected thing. Moon. It would seem, what's new on the Moon? People were already wandering around it, the Americans had been there for 40 years, a lot of all kinds of automatic equipment were flying there. But it's not so simple. There are still discoveries to come with the Moon, too. We have a good (more or less) study of the visible hemisphere of the Moon facing the Earth. And we know very little about its other side. There was not a single automatic device, not a person, not a single soil sample - in general, there was nothing there, they only looked at it a little from afar. What was the problem, why didn’t they fly there? Because, being on the far side of the Moon, you lose contact with the Earth. At the very least, without some kind of repeaters or radio relay lines, you cannot communicate with the Earth by radio. It was impossible to control the devices. Now such an opportunity has arisen.

Two years ago, the same Japanese launched a heavy satellite around the Moon, very large, very good, weighing three tons - “Selene” (Selene) it was called then, now they gave it a Japanese name, “Kaguya”. So this satellite itself brought a radio repeater there. He threw out two small satellites, which fly one a little ahead, the other a little behind in orbit, and when the main apparatus is there, behind the Moon, and explores its far side, these relay its signals to Earth.

Today, the Japanese show the surface of the Moon directly on television - household television, on ordinary high-quality home TVs - every day. They say the quality is incomparable; I didn’t see it, they don’t give us this signal. In general, they publish their data rather sparingly, but even from what they have, it is clear that the quality is excellent.

These pictures are much better than what the Americans or we supplied 40 years ago.

Here are Japanese photographs - how the Earth appears from behind the lunar horizon. And this, of course, significantly degrades the quality for slides that are actually very high quality. Why is this necessary? Well, for scientific purposes, of course, all this is interesting, but there is one purely “everyday” problem that worries people more and more lately: were the Americans on the Moon? Some idiotic books appear on this subject. Well, none of the professionals doubt that they were. But the people demand: no, you show that they were there. Where are the remains of their expeditions, the landing vehicles, these rovers, lunar vehicles? Until now it was not possible to photograph them. Well, from Earth - none at all, we don’t see such small details. And even the Japanese, this wonderful satellite, still does not see them.

And literally in - I’ll tell you now, in how many days - in three days... today is the 12th? On the 17th, in five days, the American heavy satellite “Lunar Reconnaissance Orbiter” is supposed to go to the Moon, which will have a huge television camera with a lens like this, and it will see everything on the surface of the Moon that is larger than half a meter. They will be able to achieve a resolution of 50, and maybe even 30 cm. And then - now, after all, the fortieth anniversary of the landing will be in a month - they promise to photograph all these places, traces and so on, everything that they left forty years ago on the Moon. But this, of course, is more likely a, I don’t know, journalistic interest in this than a scientific one, but still.

Yes, everything will be faked again. Guys, learn how to make such satellites, and you will take photographs.

The Americans are seriously planning to explore and take the second step on the surface of the Moon. To do this, they generally have enough money and equipment. Now in the process... I think orders have even been placed for the production of a new system, similar to the old Apollo that took them to the Moon. I kept talking about automatic research, but still expeditions with people are also planned.

The ship will be a lunar type, an Apollo type - the one that flew, a little heavier.

A rocket of a new type, but, in general, not very different from the old Saturn - this is what the Americans flew on in the 60s, 70s - here is the current rocket, conceived now, of approximately the same caliber.

Well, now it’s not von Braun anymore, new engineers are coming up with new ones.

But, in general, this is the second incarnation of the Apollo project, a little more modern. The capsule is the same, the crew will probably be a little larger.

(I can't how much screaming there is. Are you taking in what I'm saying? Thanks, because I'm trying to hear what they're saying.)

It is very possible that these expeditions will take place. Forty years ago, Apollo was certainly justified. What people did, no machine gun could have done then. How justified this is today, I don’t know. Today, automatic devices work much better, and for the money that here again several people fly to the Moon, it seems to me that it would be more interesting... But the prestige, the politics there... Apparently, there will be a human flight again. For scientists this is of little interest. Here again they will fly there along a known trajectory.

So. Sorry that I'm in a hurry, but I understand: it's stuffy here and you need to hurry. I told you about explorations inside the solar system. Now for another 20 minutes I want to talk about research beyond the solar system. Maybe someone is already tired of this story? No? Then let's talk about the planets that have begun to be discovered outside the solar system. Their name has not yet been established; they are called “extrasolar planets” or “exoplanets”. Well, “exoplanets” is a short term, apparently it will catch on.

Where are they looking for them? There are many stars around us; there are more than one hundred billion stars in our Galaxy. This is how you photograph a small piece of the sky - your eyes widen. It is not clear which star to look for a planet, and most importantly, how to look.

Pay attention to these pictures if you can see anything there. Something is visible. Here one piece of the sky was shot with four different exposures. Here is a bright star. At low exposure it is visible as a dot, but nothing weak is produced at all. When we increase the exposure, faint objects appear, and in principle, our modern telescopes could notice planets like Jupiter and Saturn around neighboring stars. They could, their brightness is enough for this. But next to these planets the star itself shines very brightly, and it floods with its light all the surroundings, its entire planetary system. And the telescope goes blind, and we see nothing. It's like trying to spot a mosquito next to a street lamp. So, against the backdrop of the black sky, we might have been able to see it, but next to the lantern we cannot distinguish it. This is exactly the problem.

How are they trying to solve it now... actually, not trying, but solving it? They solve it in the following way: let's follow not the planet, which we may not see, but the star itself, which is bright, in general, easily distinguishable. If a planet moves around in an orbit, then the star itself, relative to the center of mass of this system, also moves a little. A little bit at all, but you can try to notice it. Firstly, you can simply notice the regular swaying of the star against the sky. We tried to do this.

If you look at our solar system from afar, then under the influence of Jupiter the sun writes out such a wave-like sinusoidal trajectory, flies like this, swaying a little.

Can this be noticed? From the nearest star it would be possible, but at the limit of possibilities. They tried to make such observations with other stars. Sometimes it seemed that they noticed, there were even publications, then it was all closed, and today it does not work.

Then they realized that it was possible to follow not the swaying of the star along the plane of the sky, but its swaying from and to us. That is, its regular approach and removal from us. This is simpler, because under the influence of the planet the star rotates around the center of mass, sometimes approaching us, sometimes moving away from us.

This causes changes in its spectrum: due to the Doppler effect, the lines in the spectrum of the star should move a little to the right and left - to longer, to shorter wavelengths - move. And this is relatively easy to notice... also difficult, but possible.

For the first time such an experiment was carried out by two very good American astrophysicists, Butler and Marcy. They conceived a large program in the middle, even in the early 90s, created very good equipment, thin spectrographs, and immediately began to observe several hundred stars. The hope was this: we are looking for a large planet like Jupiter. Jupiter revolves around the Sun in about 10 years, 12 years. This means that observations must be carried out for 10, 20 years to notice the swaying of the star.

And so they launched a huge program - they spent a lot of money on it.

A few years after the start of their work, a small group of Swiss... actually, two people did the same. These still had a lot of employees - Marcy and Butler - had them. Two people: a very famous Swiss specialist on spectra, Michel Mayor, and his then graduate student, Kvelots. They began observing and within a few days they discovered the first planet around a nearby star. Lucky! They had neither heavy equipment nor much time - they guessed which star they should look at. Here is the 51st star in the constellation Pegasus. In 1995, she was noticed to be swaying. This is the position of the lines in the spectrum - it changes systematically, with a period of only four days. It takes the planet four days to orbit its star. That is, a year on this planet lasts only four of our earthly days. This suggests that the planet is very close to its star.

Well, this is a picture. But maybe similar to the truth. This is how close - well, not so close, okay - almost how close a planet can fly next to a star. This causes, of course, colossal heating of the planet. This massive planet is open, larger than Jupiter, and the temperature on its surface - it is close to the star - is about 1.5 thousand degrees, so we call them “hot Jupiters”. But on the star itself, such a planet also causes huge tides and somehow affects it; very interesting.

And this cannot continue for long. Moving close to the star, the planet should fall to the surface fairly quickly. This would be very interesting to see. Then we would learn something new about both the star and the planet. Well, so far, unfortunately, there have been no such events.

Life on such planets close to their stars, of course, cannot exist, but life interests everyone. But year after year, these studies yield more and more Earth-like planets.

Here's the first one. This is our solar system, drawn to scale. The first planetary system near the star 51st Pegasus was like this, a planet right next to the star. A few years later, a more distant planet was discovered in the constellation Virgo. In a few more years - even more distant, and today planetary systems of nearby stars are already being discovered, almost exact copies of our Solar one. Almost indistinguishable.

If - well, of course, these are drawings, we have not yet seen these planets and do not know what they look like. Most likely, something like this, similar to our giant planets. If you go online today, you will see a catalog of extrasolar planets. Any search in any Yandex will give it to you.

Today we know a lot about hundreds of planetary systems. So I literally went into this directory last night.

To date, 355 planets have been discovered in approximately 300 planetary systems. That is, in some systems 3-4 have been discovered, there is even one star in which we have discovered five... We - this is too strong a word: the Americans have mainly discovered, and we are only looking at their catalog, we do not yet have such equipment . By the way, Butler and Marcy still took the lead; now they are the leading discoverers of extrasolar planets. But not the first, but the Swiss were the first.

You see, what a luxury: three and a half hundred planets, which no one knew 15 years ago; did not know at all about the existence of other planetary systems. How similar are they to solar ones? Well, here you go, star 55 Cancer. One giant planet has been discovered there, and so in scale it corresponds directly to our Jupiter. This is the solar system. And several giant planets near the star. Here we have Earth, there Mars and Venus, and in this system there are also giant planets like Jupiter and Saturn.

Not very similar, I agree. I would like to discover planets like Earth, but it is difficult. They are light and do not influence the star so much, but we still look at the star and discover planetary systems based on its vibrations.

But in the planetary system closest to us, near the star Epsilon Eridani - those who are older probably remember Vysotsky’s song about Tau Ceti, and those who are a little older remember that in the early 60s the search for extraterrestrial civilizations began near two stars - Tau Ceti and Epsilon Eridani. It turned out that they were not looking at it in vain; it has a planetary system. If you look at it in general, it is similar: here is Solnechnaya, here is Epsilon Eridani, it is similar in structure. If we look closer, we do not see small planets near Epsilon Eridani where there should be terrestrial planets. Why don't we see? Yes, because it is difficult to see them. Maybe they are there, but it is difficult to notice them.

How can they be noticed? But there is a method.

If we look at the star itself - we are now looking at the Sun - then sometimes against the background of the surface of the star we see a planet passing. This is our Venus. We sometimes see Venus and Mercury passing against the background of the Sun. When passing against the background of a star, the planet covers part of the surface of the stellar disk, and, therefore, the flux of light that we receive decreases slightly.

We cannot see the surface of distant stars in the same detail; we perceive them simply as a bright point in the sky. But if you monitor its brightness, then at the moment the planet passes against the background of the star’s disk, we should see how the brightness decreases a little, then recovers again. This method, the method of covering a star with planets, turned out to be very useful for detecting small, terrestrial-type planets.

For the first time, the Poles discovered such a situation. They observed - they have a Polish observatory in South America - they observed the star, and suddenly the brightness decreased, decreased just a little (and this is a theoretical curve). It turned out that a hitherto unknown planet passed against the background of the star. Now this method is being exploited with all its might, and no longer from Earth, but mainly from space. The accuracy of observations is higher, the atmosphere does not interfere.

The French launched the relatively small Corot space telescope (COROT) for the first time two years ago - a year and a half ago. Well, there, the French are with the Europeans, in cooperation with other Europeans. And a month ago - three weeks ago - the Americans launched the large Kepler telescope, which is also engaged in such observations. They look at a star and wait for a planet to pass in front of it; to avoid mistakes, they look at millions of stars at once. And the likelihood of catching such an event, of course, increases.

Moreover, when a planet passes against the background of a star, starlight passes through the atmosphere of the planet, and we can, generally speaking, even study the spectrum of the atmosphere; at least we can determine its gas composition. It would be nice to get an image of the planet in general. And now we have already come close to this, well, actually, we have not come close, but we have learned to do it. How?

We came up with systems for improving image quality in telescopes. This is called "adaptive optics". Look here: this is a diagram of the telescope, this is its main mirror, which focuses the light. I’m simplifying a little, but the fact is that when passing through the layer of atmosphere, the light is blurred, and the images become very low-contrast and unclear. But if we bend the mirror so that it restores the quality of the image, then from the blot we will get a more contrasting, clearer, sharper pattern. The same as you could see from space, but on Earth. So to speak, let's fix what the atmosphere has ruined.

And using this method, at the end of last year, in November 2008, next to the image of the star - it is like this for technical reasons, it has nothing to do with the star itself, just a glare from it - three planets were found. They saw it, you understand. They didn’t just find out that they were near the star, but saw them.

And then, around the same time, in my opinion, also at the end of November, this American Hubble, which flies in orbit next to the star Fomalhaut, closed it with a shutter, discovered a dust disk and, looking closely, saw a giant planet here too. The filming was carried out two different years, it moved in orbit, it is absolutely obvious that this is a planet.

What is the joy of this discovery? Now we have an image of the planet, we can analyze it for its spectral composition and see what gases are in its atmosphere.

And this is what biologists offer us - what four biomarkers should we look for in the planet’s atmosphere in order to understand whether there is life there or not.

Firstly, the presence of oxygen, best in the form of O 3 - ozone (it leaves good spectral lines). Secondly, in the infrared spectrum you can detect lines of CO 2 - carbon dioxide - which is also somehow connected with life; thirdly, water vapor, and fourthly, CH 4 - methane. It is on Earth, at least in the Earth's atmosphere, methane is a waste product of cattle, they say. It also somehow indicates the presence of life. These four spectral markers seem to be the easiest to detect on the planets. Well, someday, maybe we’ll fly up to them and see what they are made of, what the nature is like there, and so on.

Finishing this whole story, I want to remember that this is, after all, a book festival and to tell those who are generally interested in this topic that we have started publishing a series of books.

The first two have already been published, and in them, especially in the second, much more than I told you today about the planets of the solar system, about the very, very latest discoveries is written there.

And a detailed book about the Moon has now been submitted to the printing house (will be published in two weeks), because in fact a lot has been done on the Moon and very little has been said. The Moon is an extremely interesting planet both for ground-based research and for expeditions. If you are interested, you can continue to study this topic.

Thank you. Questions now, if you have any... Please.

Question. The question is: which country is the most advanced in space exploration?

V. G. Surdin. USA.

Question. Well, what about the USA?

V. G. Surdin. No, if possible. Today, either the Americans or we can fly into space, so to speak, every day on request; there are no other options. China is getting closer to us, in terms of launching into space. They also begin to carry other people's satellites and so on. But I am still interested in the scientific study of outer space, and in this sense we are probably now one of the six or seven leading countries.

The Moon, right now, has today's situation. Japanese, Chinese and Indian satellites are now flying around the Moon. In 2-3 days there will be an American one - well, Americans often fly there, and in past years they flew there, and people were there. For 40 years - almost 40 years - nothing has flown to the Moon. We generally stopped launching anything to planets a long time ago. Americans - you saw how much I showed you. That is, in a scientific sense, the Americans, of course, have virtually no competition. And in technical matters we still stick to the old ones...

V. G. Surdin. I don’t know who decided what, but this is the answer to the question.

Question. Tell me, when are these fountains of Enceladus planned?

V. G. Surdin. It is planned in four years, but will there be money or not...

Question. And when will the data... that is, observations be available?

V. G. Surdin. And this depends on what kind of rocket you can buy for the flight. Most likely, the device will be light and will fly right away. A heavy apparatus must fly from planet to planet, but if it is small, and its goal is completely definite, then it will probably fly for about four years, yes, about four.

Question. In 10 years, perhaps we will know that...

V. G. Surdin. Maybe yes.

Question. Vladimir Georgievich, your books are so interesting. I read the book “Stars” with great interest, and now I’m also reading “The Solar System” with no less interest, which you showed. It's a pity, the circulation is only 100 copies.

V. G. Surdin. No, no, there was a circulation of 400 copies because the Russian Foundation for Basic Research supported this project, and now it has been republished. And in the same series, “Stars” came out, and we are already in its second edition... You know, the circulation is today - it makes no sense to think about it at all. They print as much as they buy.

Question. Vladimir Georgievich, please tell me, how are the sizes determined—the ones you showed—of Kuiper Belt bodies very distant from the Earth?

V. G. Surdin. Dimensions are determined only by the brightness of the object. By its spectral characteristics and color, you can understand how well it reflects light. And based on the total amount of reflected light, calculate the surface area, and, of course, the size of the body. That is, we have not yet distinguished any of them in such a way as to present a picture, only by brightness.

Question. Vladimir Georgievich, please tell me where the energy for the volcanic eruptions on Io comes from?

V. G. Surdin. The energy to erupt volcanoes and keep the seas molten beneath the ice comes from the planet itself.

Question. From radioactive decay?

V. G. Surdin. No, not from radioactive decay. Basically, from the gravitational interaction of the satellite with its planet. Just as the Moon causes sea tides on Earth, there are tides not only in the sea, but also in the solid body of the Earth. But ours are small, the ocean rises only half a meter back and forth. The Earth on the Moon causes tides already several meters high, and Jupiter on Io causes tides with an amplitude of 30 km, and this is what warmed it up, these constant deformations.

Question. Tell me, please, what is our government doing to fund the development of science more?

V. G. Surdin. Oh I do not know. Well, for God's sake, I cannot answer such a question.

Question. No, well, you're still close...

V. G. Surdin. Far. Where is the government, and where... Let's be more specific.

Question. Please tell me there is information that an expedition to Mars is being prepared.

V. G. Surdin. The question is whether an expedition to Mars is being prepared. I have a very personal and perhaps unconventional view here. First of all, they cook.

Now pay attention to the name of these missiles. Where do we have them, these same American missiles? Which they are supposedly preparing - well, not supposedly, but in fact - for flights to the Moon, and the launch vehicle is called Ares-5. Ares is a Greek synonym for Mars, so rockets, generally speaking, are made with intent - made with intent - and Mars missions. It is argued that if, there, without much comfort, then 2-3 people with the help of such carriers can fly to Mars. The Americans seem to be formally preparing for expeditions to Mars somewhere around 2030. Our people, as always, say: what’s wrong, give us money - we’ll reach Mars by 2024. And now even at the Institute of Medical and Biological Problems there is such a ground flight to Mars, the guys sit in the bank for 500 days, there are many, in general, nuances, it doesn’t even look like a space flight at all. Well, okay, they sit and whatever they need, they will sit.

But the question is: should a person fly to Mars? A manned expedition with people costs at least 100 times more than a good, high-quality automatic device. 100 times. On Mars - I didn’t have the opportunity to talk about Mars at all today - a lot of interesting and unexpected things were discovered. In my opinion, the most interesting thing: on Mars they found wells with a diameter of 100 to 200 m, no one knows how deep, the bottom is not visible. These are the most promising places to search for life on Mars. Because under the surface it is warmer there, there is more air pressure and, most importantly, higher humidity. And if there is no Martian material in these wells... but not a single astronaut will ever go down there in his life, this is beyond technical capabilities. At the same time, with the money of one manned expedition, you can launch a hundred automatic ones. And balloons, and all sorts of helicopters, and light gliders, and Mars rovers, which the Americans have been running there for six years now, two Mars rovers, in two months another heavy one is flying there. It seems to me that sending an expedition with people is irrational.

Another argument against human flight to Mars: we don’t yet know what life is like on Mars, but we’ll already bring our own there. Until now, all devices landing on Mars have been sterilized, so that God forbid we do not infect Mars with our microbes, otherwise you won’t even be able to figure out which ones are which. But you can't sterilize people. If they are there... the spacesuit is not a closed system, it breathes, it throws out... in general, a human flight to Mars means infecting Mars with our microbes. And what? Who needs this?

One more argument. The radiation hazard on a flight to Mars is approximately 100 times higher than on a flight to the Moon. Calculations simply show that a person flies from Mars, even if without landing, just back and forth, without stopping, severely... with radiation sickness, in general, with leukemia. Is this... is this necessary too? I remember our cosmonauts said: give us a one-way ticket. But who needs it? Heroes, in general, are needed where they are needed. But for science, it seems to me that it is necessary to explore Mars using automatic means, this is going very well now, and we are now preparing the Mars-Phobos project for a flight to the satellite of Mars. Maybe it will come true in the end. I think this is a promising path.

Remember, in the 50-60s all deep-sea research was carried out by humans in a bathyscaphe, right? In the last 20 years, all oceanological science deeper than 1 km has been done automatically. Nobody sends people there anymore, because it’s hard to ensure a person’s life; the apparatus must be massive and expensive. Automatic machines do all this easily and for less money. It seems to me that the situation is the same in astronautics: human flights into orbit are no longer really needed, and to the planets absolutely... Well, PR, in general. But that's just my point of view. There are people who are “for” two hands.

Question. Pop question. Are there any scientifically inexplicable objects in the solar system, anything strange, but similar to traces of an alien civilization?

V. G. Surdin. To be honest, traces of civilization have not yet been discovered, although they are not excluded. If we wanted to somehow preserve our own civilization, at least the memory of it or its achievements, well, in case, I don’t know, in case of a nuclear war or, perhaps, an asteroid falling on Earth, then the main thing would be What to do is to place our databases somewhere further away. To the Moon, to the satellites of the planets, in general, away from the Earth. And I think others would do the same. But so far nothing has been found.

Question. These are these obvious rectangular objects...

V. G. Surdin. Well, there were photographs of a sphinx-shaped face on the surface of Mars. Remember the "Sphinx on Mars"? I took a photograph - the Mars reconnaissance orbiter is now flying around Mars, this is an American device with image clarity up to 30 cm on the surface of Mars - I took a photograph: it turned out to be an ordinary mountain. There was a complex of pyramids like the pyramids in Giza, these same Cheops ones, also on Mars. We took a picture: the mountains turned out to be old mountain remnants. Now we know Mars much better than the surface of the Earth, because 2/3 of us are covered with ocean, also with forests, etc. Mars is clean, all of it has been photographed down to such details. As the rover walks on Mars, it is tracked and visible from Mars orbit. You can just see the track from it and the rover itself, where it will go. So there are no traces there.

But these caves haunt me and other people. They were recently discovered and we tried to look into them. Just a vertical well the size of Luzhniki. He goes to an unknown depth. This is where you need to look. There could be anything there. I don’t know, the city is unlikely, but life is very possible.

Question. Please tell me a few words about the collider: what happened to it?

V. G. Surdin. Well, I’m not a physicist, I don’t know when it will start working, but a lot of money has been spent, which means it’s back again... Here’s another thing. They don't want to run it in winter. He eats up the energy of this entire district around Lake Geneva and in the summer there is still enough of it, but in the winter he will simply shut down all these substations. They will launch it, of course. It will probably work great in the fall. The device is very interesting.

Reply from the hall. No, they just create a lot of fears about him...

V. G. Surdin. Come on. Well, let them catch up. Fear sells well.

Thank you. If there are no more questions, thank you, see you next time.

This encyclopedia will be useful to everyone who is interested in the structure of the Universe and space physics, and who, by the nature of their activities, is associated with space exploration. It provides detailed explanations of more than 2,500 terms from a wide range of space sciences - from astrobiology to nuclear astrophysics, from the study of black holes to the search for dark matter and dark energy. Apps with star maps and the latest data on major telescopes, planets and their moons, solar eclipses, meteor showers, stars and galaxies make it a handy reference.
The book is mainly intended for schoolchildren, students, teachers, journalists and translators. However, many of her articles will attract the attention of advanced amateur astronomers and even professional astronomers and physicists, since most of the data is presented for mid-2012.

Outstanding amateur astronomers.
In the XVII-XVIII centuries. the small staff of state observatories was mainly occupied with applied research aimed at improving the time service and methods for determining geographic longitude. Therefore, the search for comets and asteroids, the study of variable stars and phenomena on the surface of the Sun, Moon and planets were mainly carried out by amateur astronomers. In the 19th century Professional astronomers began to pay more attention to stellar astronomical and astrophysical research, but even in these areas, science lovers were often in the forefront.

At the turn of the 18th and 19th centuries. worked as the greatest of amateur astronomers - musician, conductor and composer William Herschel, whose faithful assistant and successor was his sister Caroline. From the point of view of amateur astronomy, V. Herschel’s main merit lies not in the discovery of the planet Uranus or the compilation of catalogs of thousands of nebulae and star clusters, but in demonstrating the possibility of handicraft manufacturing of large reflecting telescopes. This is what determined the main direction of amateur telescope construction for several centuries to come.

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