Surdin lectures on astronomy. Discovery of new planets. The greenhouse effect and the planet's climate

The lecture was delivered 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 is the future without science. And since science is what our foundation is engaged in - public lectures, grants, scholarships for students, graduate students, for those people who are engaged in fundamental natural sciences; we also organize public lectures, publish books. It is surprisingly pleasant that at the stand of the Moscow store all non-fiction books that are on sale are practically 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 of three lectures, which - the first, now, today, the second will be tomorrow, and one more on Sunday, on 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. All the same, it was supposed to show pictures in an environment corresponding 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 open up before us?

We live on a planet, we have no other way of existence. Until now, the planets have been discovered very rarely, and all have been unsuitable for our life. The situation has changed dramatically in recent years. The planets began to open in tens and hundreds - both in the solar system and beyond the solar system. There is room for fantasies to unfold, at least to find a place for some expeditions, at least, and maybe for the expansion of our civilization - and for the salvation of our civilization if something happens. In general, we need to keep an eye on the place: these are future footholds for humanity, at least some of them. Well, I think so.

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 somewhat different area under the solar system, and the concept of "planet" has expanded. But let's see what we have on this score.

First, how did we represent it - well, in fact, the scheme of the solar system has not changed, right? Eight large ... (So, the laser pointer on this thing does not work, it will be a classic ...) Eight large planets and many small ones. In 2006, the nomenclature changed - you remember, there were 9 major planets, now there are only 8 of them. Why? Divided into two classes: classical large planets such as the Earth and giant planets remained under the name "planets" (although it is always necessary to stipulate - "classic planets", "more than a planet"), and a group of "dwarf planets" - 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 really special, and they did the right thing to be singled out. But now we only have 8 major planets left. There is a suspicion that there will be bodies near the Sun, there is confidence that there are a lot of bodies far from the Sun, and they are constantly found in the intervals between large planets, I will also talk about this. All this little thing is called "small objects of the solar system."

(Voice from the audience. Vladimir Georgievich, a microphone is better, you can take it: you can't hear it very well from behind.) It is unpleasant to listen when people speak through a microphone, but in general it is 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 earth-like, similar to the Earth. Here they are four. They are all different, they are not like Earth in any sense, only in terms of size. We will talk about them, well, and about some other bodies.

It turns out that not even all of these planets are still open. In what sense are they open? At least they are overlooked. We have already seen almost all the planets from all sides, the last one, closest to the Sun, remains - Mercury. We have not yet seen her from all sides. Do you know that there can be surprises. Let's say that the far side of the moon turned out to be not at all the same as the visible one. It is possible that some surprises will be on Mercury. They flew up to him, spacecraft flew past him three times, but they could not photograph him from all sides. There is still 25 or 30 percent of the surface that has not yet been seen. This will be done in the coming years, in 2011, the satellite will already start working there, but there is still a mysterious reverse side of Mercury. True, he 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 are absolutely not yet exhausted. Basically, they are clustered 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.

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

But on the surface of the Earth, many astronomical instruments have really 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 the largest astronomical instruments there are today.

The largest of them - 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 the telescope is the diameter of its mirror, since this is the area of ​​light collection; hence, the depth of gaze 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. This size is only a camera. The telescope itself weighs up to 1000 tons, the mirror weighs tens of tons, and cameras of this scale. They are being cooled; CCDs are the kind of sensitive plate that works in our cameras today. There is about the same type of CCD, but they are cooled to almost absolute zero, and therefore the sensitivity to light is very high.

Here's a modern CCD. This is a set of approximately the same ... Just like in a good consumer camera we have 10-12-megapixel plates, but here they are mosaic, and in total, a much larger light-collecting area is obtained. And, most importantly, at the moment of observation, you can immediately drop this data into a computer and compare, say, the pictures obtained now and an hour earlier or days earlier, and this is how we notice new objects.

The computer immediately identifies those luminous points that have moved against the background of fixed stars. If a point moves quickly, within tens of minutes or hours, then it is not far from the Earth, then it is a member of the Solar System. It is immediately compared with a data bank: if this is a new member of the solar system, then a discovery has been made. Over the entire 19th century, about 500 minor planets - asteroids - were discovered. For the entire - almost the entire - of the 20th century, 5000 asteroids were discovered. Today, about 500 new asteroids are discovered every day (more precisely, every night). That is, without a computer, we would not have had time to write them even to catalogs, discoveries are made with such frequency.

Look at the statistics. Well, the 19th century, of course, I didn’t draw ... (I don’t know, is the pointer visible against the background of this? Bad, of course, but visible.) So until 2000, the quantitative growth of small bodies in the solar system, asteroids ( well, they are not that small - tens, hundreds of kilometers in size). Since 2000, new projects, such as large telescopes, have dramatically accelerated their growth, and today we have about half a million asteroids discovered in the solar system. Well, the truth is, if you collect all of them in a heap and make one planet out of them, then it will turn out to be a little larger than our Moon. In general, the planet is small. But their number is gigantic, the variety of motions is huge, we can always find asteroids close to Earth, and, accordingly, explore.

Here is the situation around the Earth, look. This is the Earth's orbit, here is our planet itself, a dot, and asteroids scurrying past it. Well, this is not in real time, of course, this was the 2005 situation, but look how close they fly and how often they approach the Earth. When they talk about the asteroid hazard, it is sometimes exaggerated - in order to obtain funding or in some other interest, astronomers do it. But, in general, this danger is real, and it is necessary to think about it, at least to predict the movement of asteroids and to foresee the situation.

This is how telescopes see an asteroid moving against a background of stars. Sequential shots: firstly, during the exposure, the asteroid itself moves, it is obtained 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.

I am showing you this slide for a reason. This 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 will crash into the atmosphere (it is small, several meters in size, there was nothing terrible), crash into the Earth's atmosphere. Where exactly - here 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, here 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 noticed.

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

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

The situation with other small bodies, namely, with the satellites of the planets, is also changing very quickly. Here in 1980 is the number of satellites belonging to each of the planets. For the Earth, of course, their number has not changed, we still have one Moon, Mercury and Venus do not have satellites at all. Mars still has two of them - Phobos and Deimos, but the giant planets, and even small Pluto, have discovered a huge number of new satellites over the past two decades.

The last one near Jupiter was discovered in 2005, and today there are 63 satellites. All school textbooks no longer correspond to reality in any way.

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: here, 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 he became a satellite of Saturn, so he is considered not a planet, but a satellite.

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

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

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

But with the help of the Hubble telescope in 2005, it was possible to find two more near Pluto and Charon - so, if you will 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 such names from mythology associated with hell: Hydra and Nikta. There are still enough 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, there is still enough. At least enough for satellites.

Each planet is capable of keeping satellites next to itself, in a limited space. This is, for example, the Sun, the Earth, and this is the area that the Earth controls with its gravity - the Roche zone. The moon moves within this area, and therefore it is associated with the earth. If it was a little further than its border, it would walk like an independent planet. So, every planet, especially the giant ones - Jupiter and Saturn - these regions, which are controlled by its own gravity, are very large, and therefore there are many satellites, they have to be bled out. But their nature is different, this is a fact.

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

In general, the process of the formation of the solar system becomes 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. At first, large planets were formed, then matter attracted by gravity began to grow around them. From it satellites were formed, rings; all giant planets have both rings and satellites. This process was reminiscent of the formation of the solar system itself.

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

At the far reaches of the solar system for about 15 years - already more, about 20 years ago - an area inhabited by very special microplanets was discovered. We now call it the Kuiper Belt, because 50 years ago the American astronomer Kuiper predicted its existence. Behind the orbit of Neptune lies the orbit of Pluto, and now we understand that he is a member of a large team flying in the outer regions of the solar system. Today, several thousand objects have already been discovered there, the largest of them you see.

For the scale, the Earth and the Moon and Pluto - by the way, this is a real image of Pluto, we do not have anything better today, because it is far away and it is difficult to see the details, but the Hubble telescope was able to see something there. These are drawings; of course, we do not see the surface 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, he is probably a member of the large brotherhood of dwarf planets. They are independent and interesting.

These are all drawings. Next to a scaled image of the Earth, but these are all drawn pictures. How do we imagine the largest objects in the Kuiper belt? It is impossible to see their surface: firstly, they are far away, and secondly, they are very poorly illuminated by the Sun, since they are far away. But note: Pluto has three satellites, and Eris has at least one (already discovered), Haumea has two large satellites. 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 is cold there. And Pluto, which moves in an elongated orbit and sometimes flies up to the Sun - you can see it here: sometimes it moves away from the Sun, and there, of course, everything freezes, ice and snow lies on the surface. Sometimes, at this point of the orbit, it approaches the Sun, and then its atmosphere, more precisely, the ice on its surface, melts, evaporates, and the planet envelops its atmosphere for several decades, then again the atmosphere freezes out and in the form of snow falls on the planet's surface ...

This, by the way, is a variant of the future for the development of Earth civilization. Today the bodies are cold, but someday the situation will change. Let's see what astronomers predict for the Earth today. We imagine the modern Earth. In the past, the Earth's atmosphere was probably more gas-rich, and even the gas composition was different. At least it was denser and more massive, because gas is lost from the Earth's atmosphere. Every second, about 5 kg of gas is ejected from the earth's atmosphere. It seems to be 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 do not mean today, in general the weather changes frequently, and the brightness of the sun rises constantly. Every billion years, for about 8, 10%, the heat flux from the Sun increases. 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 leave with it, as the air pressure will decrease and the water will begin to evaporate faster. In general, the Earth will dry up. It's hard to say about the temperature; maybe the temperature will not change much, but if it dries up - that’s for sure, it will lose the gas shell. Therefore, one must look out for some kind of springboard for development, and distant cold planets today can become warm and favorable in billions of years.

Here is a picture, 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 flux, simply because of its large size, and the Earth will come to an end. It is not even clear if the Earth will survive as an individual body. It is possible that the Sun will expand up to the Earth's orbit and absorb it, the Earth will dive into the Sun. But even if this does not happen, the end of the biosphere will come.

In general, the area in the solar system where life is possible - it moves. It is usually called the "zone of life", and now look: 4.5 billion years ago, the zone of life captured Venus, it was not very hot there, not like it is today, well, it also captured the Earth, of course, because 4 billion years ago on Earth there was already life. As the brightness of the Sun increases, the zone of life moves away from it, the Earth is today in the zone of life, and Mars falls into the zone of life. If Mars retained its atmosphere to this day, the temperature on it would be comfortable, the rivers would flow, and life could be. Unfortunately, in that period, until the zone of life reached it, Mars had already lost its atmosphere, it weakly attracts gases, they evaporate, and today, even with a favorable situation, it is so dry that it is unlikely ... there is no life on its surface, but under the surface, it is still possible, maybe.

Well, further on, the life zone will move faster and faster away 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 will talk about them now.

Jupiter has many moons. Basically, this is a trifle, but the four so-called "Galilean satellites", discovered just 400 years ago, in 1610, by Galileo - they 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.

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

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

Of course, it is cold on the surface of Io. You can see that the gases here have frozen and laid down as snow on the surface. But the closer you are to the volcano, the warmer. It's like a campfire, you know, in winter, a step to the side by a campfire is cold, a step to a campfire is hot, and you can always find an area where the temperature is comfortable next to the bonfire. An even more accurate analogy is the black smokers at the bottom of our oceans. You know: small volcanoes are, more precisely, geysers that work at the bottom of our oceans. The surrounding water has a temperature of about freezing, and leaving these black smokers is about 400 degrees Celsius. And on the border between boiling water and frost, life flourishes next to black smokers. It is possible that some form of life also exists in the area around the volcanoes of Io at a comfortable temperature. There was no way to check it yet, no one sat there. There were only orbital, not even orbital - such flyby studies are fast.

The second satellite, more distant from Jupiter, is Europa. It is, of course, cooler, volcanoes do not work there, and its entire surface resembles our Antarctica. This is a solid ice dome - not even a dome, but just an ice crust covering the satellite - but, judging by the calculations, at a depth of several tens of kilometers under this solid ice, the water is liquid. 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 of the bowels of the planet melts the water. The same is probably the case in Europe. I would very much 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 - they are most likely cracks. Here - these are, however, strongly contrasting colors, this is an unnatural color - here we look closely at them and see that fresh ice, it goes along the stripes. Most likely, there are times when the ice dome cracks and water rises from there. Unfortunately, we haven't seen the sources yet.

This is how the ice dome of Europe looks in real colors. There are hummocks, icebergs, it can be seen that some kind of movement occurs near the ice, shifts are visible, ruptures. But no one has yet managed to see a real crack so that one can look there, into the ocean.

In recent years, when this discovery was made, astronomers - more precisely, astronautics - 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 even 100, here the calculations are not very accurate. The crack has not yet been found. There are projects, mostly within the framework of NASA, well, we have some people in our space institutes who are engaged in this. They thought to make complex devices with a nuclear energy source that would melt the ice and break through there, in general, on the brink, and maybe beyond the technical capabilities.

But literally last year it turned out that this should not be done. A new discovery has been made, which promises us great prospects. The discovery is not in the Jupiter system, but in the satellite system of Saturn. Saturn also has many satellites, and now, pay attention: even in this picture, of course, not all are depicted, they did not pay attention to one of the satellites at all.

This is Titan, the largest, and here I separately found a photo next to Titan, where this small satellite under the name Enceladus passes. It is so small, 500 km in diameter, that ordinary people were considered uninteresting. Now near Saturn - in orbit around Saturn - a good NASOV spacecraft, Cassini, is operating, and it flew several times to Enceladus.

And what happened? A completely unexpected thing.

This is what Enceladus looks like from afar. Also an icy surface. But it immediately strikes the eye - geologists immediately draw attention to this - 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 been falling on it for millions of years and have broken it properly. This is a geologically old surface. But the southern part does not contain a single crater. What, meteorites didn't get there? It is unlikely that they do not fall aimingly. This means that some geological process is constantly renewing the southern ice, and this immediately attracted attention. What does “refresh ice” mean? This means pouring liquid water over it and destroying meteorite craters.

We began to look closely at the southern hemisphere of Enceladus. Indeed, we saw powerful cracks there, you see what a deep canyon in the icy surface.

(Well, I can't help but regret that this audience is not dark, but this audience is completely unsuitable for slideshows. It's all very beautiful in fact. Well, sometime next time we will gather in a dark environment, and then you will see more . But here, too, you can see something.)

And one area, literally at the south pole of Enceladus, turned out to be very interesting. Here are the longitudinal four stripes. In English, they began to be called "tiger stripes", these are stripes not in the sense of the stripes that are on the belly of the tiger or, wherever, on the back, but these are the ones that remain from the claws when the tiger strokes you. And indeed, it turned out to be those very claw marks. That is, breaks on the surface.

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

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

In artificial colors, strongly enhanced in brightness and contrast, it looks like such a super-fountain that hits directly into space, which flies into space from the surface of Enceladus. But this photo is the orbit of Enceladus around Saturn: here is Enceladus, along the orbit he scattered this snow, steam and ice. That is, one of the rings of Saturn, the outermost ring, is, in essence, the substance thrown out by Enceladus - water vapor and ice crystals thrown out by Enceladus recently.

Well, this, of course, is 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. An infrared device, a camera on board the Cassini, he photographed the stripes, and you see that they are warm, that is, liquid water underneath the ice. Here it comes right up to the surface of the ice and flies up through the cracks.

At the end of last year, the orbit of "Cassini" was changed so that it flew right through these fountains, literally passed at the surface of the satellite at an altitude of 20 km and scooped up this water. And he proved that it really H 2 O flies out of there. Unfortunately, there are no biological laboratories on board the Cassini, so he cannot analyze this water for the composition of microorganisms. No one imagined that such a find would happen at all. But now no one, almost no one, is interested in Europe, where the 100-kilometer-long shell is icy, it must be drilled and drilled for some unknown reason. Everyone re-aimed at Enceladus, from which water flies out by itself, and you just need to either fly over or land the device on the surface and analyze this substance for its biological composition.

It is very interesting, and now just a lot of projects are aimed at researching Enceladus.

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

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

Look, it looks like a sea sponge. The reason why such a structure has arisen in him is also unclear. As if the March snow melted by the sun's rays. You cannot keep track of everything, for each satellite there is still not enough scientific instruments and apparatus. We will only examine them from afar, but the time will come - they will sit down and look there.

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

This probe, the cost of the entire project $ 3 billion, is, in fact, at present times 10 times more than a traditional spacecraft. This thing was launched a long time ago, in 1997, it was moving along a very complex trajectory, because the apparatus was heavy, and it could not be immediately thrown to Saturn. He flew from Earth to Venus, that is, into the solar system, then back to Earth, then again flew up to Venus. And every time it flew past the planets, a little bit due to their attraction, it gained additional speed. Eventually, a third pass near Earth threw him towards Jupiter. Jupiter pushed it very strongly, and the device reached Saturn in 2004. And now it has entered orbit, this is the first satellite in the history of cosmonautics, an artificial satellite of Saturn, and it has been working there for four, almost 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 the Cassini got to it. It is covered with an atmosphere, the atmosphere is cold, opaque, all this is a haze, and no one knew what was on the surface.

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

This is a snapshot of the southern portion of Titan. Here frozen ice, obviously, lies, like our Antarctica. There were many interesting questions about the composition of the atmosphere and the surface.

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

Here is the Huygens lander, which was made by the Europeans, made very soundly. You will be surprised: the company "Mercedes-Benz" made it, and therefore it really reliably ... You know, not very reliably, in fact, it worked. I am not in the sense of cars, but this device - there were two duplicated radio channels, and so one radio channel still went out of order; it's good that they were duplicated. Half of the information was missing, but we got half.

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

Then he throws out parachutes - one parachute, the second - and gradually descends to the surface by parachute. He parachuted down for two hours until he touched the surface. And while these two hours he was descending by parachute, he photographed, of course. Not very high quality, well, it was very difficult.

You know, I want to tell you about everything, a lot of interesting things were 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 to see anything at all!

These are clouds. Now, from a height of 8 km, we see the surface of Titan. Now he has 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 crossed sections, mountainous, and meanders of some rivers are visible on them. What flows in these rivers, what kind of liquid - maybe the same methane, most likely, or flowed at one time. But look: obviously, the delta, further the seabed, the mountain system here - very much resembles the Earth in geography. And in terms of the atmosphere - generally a copy of the Earth. The atmosphere of Titan, unlike all other planets ...

Well, take Venus: the atmosphere there is pure CO 2, poison for us. On Mars: CO 2, carbon dioxide, poison. Take Titan: the atmosphere is composed of molecular nitrogen. And now we have here 2/3 of molecular nitrogen. In general, for us it is just a normal neutral environment. Oxygen is not 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 like in this room. The temperature, however, is chilly, but that's okay. Hot is deadly for experiments, cold is even favorable, because the apparatus does not need to be cooled, it will cool itself.

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

This is the only television frame transmitted to her. There is a horizon, this is right next to the apparatus, there are cobblestones - obviously, this is frozen water; at a temperature of minus 180, water is like a stone, solid, and so far we do not know anything more about it.

Why is it 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 exploring Titan, we can understand the first processes that preceded biological evolution on Earth. Therefore, a lot of attention is paid to it and it will still be investigated. This is the first satellite of the planet (except for the Moon), on which the automatic station has landed.

A question from the audience. What about Huygens?

V. G. Surdin. Huygens is over. The battery ran out, I worked for two hours, and that's it. But not only. Everything there was calculated so that he worked for two hours. Because he did not have enough transmitter power to communicate with the Earth, but he communicated through the orbiter, and that flew away, and that's it, the connection stopped. No, well, well, did his job.

Asteroids. Spacecraft have already flown up to asteroids, now we can already see what kind of bodies they are. There was no big surprise, we really imagined asteroids: debris, large or small, preplanetary bodies.

This is how the asteroids look like when spacecraft fly by, this is a series of frames, just for you to see. It is clear that they experience mutual collisions.

See what a huge crater has been discovered on the asteroid Stern. Sometimes the craters are so large that it is not clear how this body itself did not break on impact.

For the first time it was possible to fly up recently and almost land on the surface of an asteroid. Here is this asteroid. Who do you think did it, which country?

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

The Japanese apparatus, indeed the first interplanetary Japanese apparatus, flew up to this asteroid with the Japanese name Itokawa - but, roughly speaking, they specially opened it for this case and gave this name. A very small asteroid, only 600 meters in size along the long axis - well, from the Luzhniki stadium.

Such a small apparatus flew up to him, which - here in this photo you can see a shadow from it - he photographed his shadow falling on the surface of the asteroid Itokawa.

Gradually, he approached him (well, this, of course, you see a drawing), did not sit on its surface, but hovered above it at a distance of 5 or 7 meters. Unfortunately, he began to junk ... - here are the Japanese, but all the same it began to junk - electronics, and then we are not quite sure what happened to him. He had to drop a small robot on the surface - here he is drawn here - the size of ... this is the size of a 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 did not just hit the surface.

But a much more interesting experiment was made. 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 there, of course, does not work, there is an airless space. Therefore, he fired at the surface with small metal balls, the balls caused such micro-explosions, and part of the dust from this asteroid should have got into this tube. Then it was packed (had to be packed) in a special capsule, and the device moved towards the Earth. This experiment was specifically for the delivery of asteroid matter to Earth. For the first time in history. But the engines have gone bad, and instead of flying to the Earth for a long time, it is now slowly, slowly winding up revolutions around the Sun and nevertheless slowly approaching the Earth. Maybe in a year and a half, if he is still alive, he will reach Earth and for the first time bring soil samples from an asteroid.

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

It was to this nucleus of comet Wild-2 that the Stardust spacecraft flew up in 2006. It was arranged so that, without landing on the surface of a comet, take a sample of its substance.

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

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

See what a micrograph of a dust particle flying inside this substance looks like. Here it crashes with a cosmic speed, 5 km per second, pierces this airgel and gradually slows down in it, without evaporating. If it hit a hard surface, it would evaporate instantly, nothing would be 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 the capsule, and it returned to Earth. Flying past the Earth, the device dropped it by parachute.

They found it in the Arizona desert, this capsule was opened, and you see how the composition of this trap is being investigated. 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 look for this business using micrographs, 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 very high temperatures. And we thought that, on the contrary, the solar system and the matter of comets have always been at a low temperature. Now this problem hangs: 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 dashing trouble is the beginning.

By the way, they continued. To one of the comet nuclei - comet Tempel-1 - the American device "Deep Impact" also flew up and tried to click and see what was inside. A blank was dropped from it - in my opinion, about 300 kg of weight, copper - which, with the speed of the satellite's flight, crashed right here; this is the moment of the collision. It penetrated to a depth of several tens of meters, well, and there it slowed down, exploded, just from kinetic energy: it flew very quickly. And the substance ejected from the inside was spectrally analyzed. So, we can say, have already dug inside the nuclei of comets. This is very important, because the crust is cometary - it is processed by the sun's rays, the solar wind, but it was possible to capture matter from the depths for the first time. So comet nuclei are well researched. Today we already present them in such a variety.

This is the nucleus of Halley's comet, remember, in 1986 it - well, someone must remember - flew up to us, we saw it. And these are the nuclei of other comets, which have already been approached by spacecraft.

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

Why exactly there, near the Sun? Because it is difficult for astronomers to observe areas close to the Sun. The sun is blinding, and the telescope does not see anything there. The sun itself is visible, of course, but what is next to it? Even Mercury is very difficult to see through a telescope, we do not know what it looks like. And what's inside the orbit of Mercury is a complete mystery.

Recently, the opportunity to look at these areas has emerged. From orbiters, photographs of the vicinity of the Sun are now taken every day, covering the solar disk itself with a special shutter so that it does not blind the telescope. Here it is on a leg, this damper. And now we see: well, this is the solar corona and what may be next to the sun.

About once a week, small comets are now opening, which have approached the Sun at 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, which evaporate so weakly away from the Sun that you will not notice them. But when approaching the Sun, they begin to evaporate very actively, sometimes hitting the solar surface, perishing, sometimes flying by and almost completely evaporating, but now we know that there are a lot of them.

By the way. Well, since you came here, then you are interested in astronomy. You can discover comets without a telescope, but with only 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 flown up to the Sun. Astronomy lovers do that. I know at least two boys in Russia who live in the village, they do not 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, five even comets, which received his name and, in general, everything is fair. Just by having such perseverance and working in this direction every day. Well, many people abroad are also doing this. So it's now easier to discover the 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, it is possible that we will discover new small planets. They have even been given a preliminary name. Sometime in the 19th century, the existence of a planet was suspected there, they gave it the name Vulcan, but it was not there. Now these small bodies, which have not yet been discovered, but, perhaps, will be discovered in the near future, have been called "volcanoids".

And now an unexpected thing. Moon. It would seem, what's new on the moon? Already people wandered along it, 40 years as the Americans were there, a lot of all automatic equipment flew there. But not everything is so simple. With the Moon, there are still discoveries ahead. We have studied well (more or less) the visible hemisphere of the Moon facing the Earth. And we know very little about the reverse side of it. There was not a single automatic apparatus, not a person, not a single soil sample - in general, there was nothing there, only they looked at it a little from afar. What was the problem, why didn't you fly there? Because, being on the far side of the moon, you lose touch with the Earth. At least, without repeaters of some kind of radio relay lines, you cannot communicate with the Earth by radio. It was impossible to control the devices. Now such an opportunity has appeared.

Two years ago, all the same Japanese launched a heavy satellite around the Moon, very large, very good, weighing three tons - it was called Selene then, now they gave it the Japanese name, Kaguya. So this satellite itself brought a radio relay there. He threw out of himself two small satellites, which fly one a little ahead, the other a little with a lag 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 daily show the surface of the Moon directly on television - everyday, on ordinary high-quality home televisions. They say the quality is unmatched; I have not seen, they do not give us this signal. In general, they publish their data rather sparingly, but even from what is available, it is clear that the quality is excellent.

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

Here are Japanese photographs of how the Earth appears from the lunar horizon. And this, of course, significantly degraded the quality for slides, in fact, very high quality. Why is this needed? Well, for scientific purposes, of course, all this is interesting, but there is one purely “everyday” problem that has been worrying more and more people lately: were the Americans on the moon? Some idiotic books appear on this score. Well, none of the professionals doubt that there were. But the people demand: no, you show that they were there. Is that where the remnants of their expeditions, the landing craft, these rovers, mooncars are? Until now, it has not been possible to photograph them. Well, from the 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 will say now, in how many days - in three days ... is today the 12th? On the 17th, in five days, the American heavy satellite "Lunar Reconnaissance Orbiter" should go to the Moon, which will have a huge TV camera with such a lens, 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 even then - now, after all, the fortieth anniversary of the landing will be in a month - they promise to photograph all these places, footprints and so on, everything that they left forty years ago on the Moon. But this, of course, is more, I don’t know, a journalistic interest in this than a scientific one, but all the same.

Yes, everything will be forged again. Guys, learn how to make satellites like this, and you will take photos.

The Americans seriously conceived to master, to take the second step on the lunar surface. To do this, they, in general, have enough money and equipment. Now in the process ... I think orders have even been placed for a new system, similar to the old Apollo that took them to the moon. I've been talking about automatic research all the time, but still expeditions with people are also supposed.

The ship will be of the lunar type, of the Apollo type - the one that flew is 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 in the 60s, 70s - this is the current rocket, conceived now, of about the same caliber.

Well, now it's no longer von Braun, there are new engineers coming up with.

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

(I can't how much shouting there. Do you take in what I'm saying? Thank you, because I'm trying to hear what they are talking about.)

It is very possible that these expeditions will take place. Forty years ago, Apollo was definitely acquitted. What people did, no automaton would have done then. How justified it is today, I do not know. Today, automatic devices work much better, and for the money that several people fly to the moon again, I think it would be more interesting ... But prestige, politics there ... Apparently, there will be a man's flight again. For scientists, this is of little interest. Here again they will fly there along a well-known trajectory.

So. Excuse me for being in a hurry, but I understand: you are stuffy here, and you need to hurry. I have told you about research 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, here, "exoplanets" is a short term, apparently it will take root.

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

Pay attention to these pictures if you can see anything there. Something is visible. One piece of sky is shot here with four different exposures. Here is a bright star. At low exposure, it is visible as a dot, but nothing weak at all turns out. As we increase the exposure, faint objects appear, and in principle, our modern telescopes could detect planets like Jupiter, Saturn in nearby stars. 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 don't see anything. It's like trying to see a mosquito next to a street lamp. So we might have seen against the background of the black sky, but next to the lantern we cannot distinguish it. This is exactly the problem.

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

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

Can you see it? From the nearest star it would be possible, but at the limit of possibilities. We tried to make such observations in 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 us to us. That is, by approaching and removing it regularly from us. This is easier, because under the influence of the planet, the star turns around the center of mass, now approaching us, then moving away from us.

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

For the first time, such an experiment began to be carried out by two very good American astrophysicists, Butler and Marcy. In the middle, even in the early 1990s, they conceived a large program, created very good equipment, fine spectrographs, and immediately began to observe several hundred stars. The hope was this: we are looking for a large planet like Jupiter. Jupiter orbits the Sun in about 10 years, in 12 years. This means that it is necessary to conduct observations for 10, 20 years to notice the wobbling of the star.

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

A few years after the start of their work, a small group of Swiss ... in fact, two people did the same. These still had a lot of employees - Marcy and Butler - had. Two people: the very famous Swiss spectra specialist Michel Mayor and his then graduate student, Quelots. They began observing and a few days later discovered the first planet of a nearby star. Lucky! They had neither heavy equipment, nor much time - they guessed which star to look at. Here is the 51st star in the constellation Pegasus. In 1995, she was seen wiggling. This is the position of the lines in the spectrum - it changes systematically, and with a period of only four days. It takes four days for the planet to orbit around 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 - well, not that much, okay - almost so close a planet can fly next to a star. This causes, of course, a 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, somehow affects it; very interesting.

And this cannot go on for long. Moving close to the star, the planet should fall to the surface rather quickly. It would be very interesting to see this. Then we would learn something new about the star and about the planet. Well, so far, unfortunately, there have not been such events.

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

Here is the first one. This is our solar system, so drawn to scale. The first planetary system of the 51st Pegasus star was like this, right next to the star planet. A few years later, they discovered a more distant planet in the constellation Virgo. A few years later - even more distant, and today planetary systems of the nearest stars, almost exact copies of our Solar, are already being discovered. 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, it looks like 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 just went into this directory last night.

To date, 355 planets have been discovered in about 300 planetary systems. That is, in some systems, 3-4 are open, there is even one star, in which we found five ... We - this is too strong: the Americans basically discovered, and we only look at their catalog, we do not have such technology yet ... By the way, Butler and Marcy nevertheless took the lead, now they are the leading discoverers of extrasolar planets. But not the first, here, but the first still turned out to be the Swiss.

You see what a luxury: three and a half hundred planets that no one knew 15 years ago; did not even know about the existence of other planetary systems. How similar are they to the sun? Well, here you are, please, the star of the 55th Cancer. There one giant planet is open, 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 the Earth, there, Mars and Venus, and in this system, too, giant planets such as Jupiter and Saturn.

Not very likely, I agree. I would like to discover planets like Earth, but it's difficult. They are light and do not affect the star so much, but we still look at the star, discover planetary systems by its oscillations.

But in the planetary system closest to us, the star epsilon Eridani - who is older, probably remembers Vysotsky's song about tau Ceti, and who is a little older, remembers that in the early 60s the search for extraterrestrial civilizations began at two stars - Tau Ceti and Epsilon Eridani. It turned out that it was not in vain that they looked at her, she has a planetary system. If you look in general, it is similar: here is Solar, here is Epsilon Eridani, it is similar in structure. If you take a closer look, we do not see small planets near Epsilon Eridani where there should be terrestrial planets. Why can't we see? Because it's hard 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 looking at the Sun now - then sometimes against the background of the surface of the star we see how the planet passes. This is our Venus. We sometimes see against the background of the Sun how Venus and Mercury pass. Passing against the background of the star, the planet covers part of the surface of the stellar disk, and, therefore, the flow 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 follow its brightness, then at the moment the planet passes against the background of the star's disk, we should see how the brightness will slightly decrease, then it will be restored again. This method, the method of covering a star with planets, turned out to be very useful for detecting small, terrestrial planets.

This was the first time the Poles discovered such a situation. They observed - they have a Polish observatory in South America - observed a star, and suddenly the brightness went down, just a little bit went down (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 might and main, and no longer from the Earth, but mainly from space. The accuracy of the observations is higher, the atmosphere does not interfere.

The French for the first time two years ago - a year and a half ago - launched a relatively small space telescope "Korot" (COROT). 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 the star and wait for the planet to pass against its background; in order not to be mistaken, 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 planet's atmosphere, 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 they have already approached this, well, in fact, they have not approached, but have learned how to do it. How?

Came up with systems for improving image quality in telescopes. This is called adaptive optics. Take a look: 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, passing through the atmosphere layer, the light is blurred, and the images become very low-contrast, indistinct. But if we bend the mirror so that it restores the quality of the image, then from the blot we get a more contrasting, clearer, sharper pattern. The same as from space you might see, but on Earth. So to speak, let's fix what the atmosphere spoiled.

And with the help of this method, at the end of last year, in November 2008, next to the image of a 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 know. We didn't just find out that they are near the star, but saw them.

And then, about, in my opinion, also at the end of November, this very American "Hubble", which flies in orbit, next to the star Fomalhaut, closing it with a shutter, discovered a dust disk and, looking closely, here I saw a giant planet too. For two different years, the shooting was carried out, 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 spectral composition and see what gases it has in the atmosphere.

And this is what biologists are offering us - what four biomarkers should be looked for in the planet's atmosphere in order to understand whether there is life there or not.

First, the presence of oxygen, best of all in the form of O 3 - ozone (it leaves good spectral lines). Secondly, in the infrared spectrum, you can find 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 testifies to the existence of life. These four spectral markers seem to be the easiest to find near planets. Well, someday, maybe, we will fly up to them and see what they consist of, what kind of nature is there, and so on.

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

The first two have already come out, and just in them, especially in the second, there is much more than I told you today, about the planets of the solar system, about the very latest discoveries it says.

And now a detailed book about the Moon has been handed over to the printing house (it will be out in two weeks), because on the Moon, in fact, a lot has been done and very little has been told. The moon is an extremely interesting planet both for ground research and in the sense of expeditions. If you are interested, you can continue to study this topic.

Thanks. Questions now, if any ... Please.

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

V. G. Surdin. USA.

Question. But for the USA?

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

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

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

Question. Tell me, these fountains of Enceladus - when is the study planned?

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

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

V. G. Surdin. And it 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 should fly from planet to planet, and if a small one, and it has a completely definite goal, then it will probably immediately and so for four years, yes, about four.

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

V. G. Surdin. Maybe yes.

Question. Vladimir Georgievich, you have such interesting books. So I read the book "Stars" with great interest, now I am also reading "The Solar System" with equal 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 RFBR supported this project, and now it has been republished. And in the same series "Stars" came out, and we already have its second edition ... You know, the circulation today - it makes no sense to think about it at all. How many people buy, so many print.

Question. Vladimir Georgievich, tell me, please, how do you determine the dimensions - which you showed - of the Kuiper belt bodies very far from the Earth?

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

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

V. G. Surdin. The energy to erupt volcanoes and to keep the seas under the ice in a molten state is taken 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. In the same way as the Moon causes sea tides on Earth, not only sea tides, but also in the earth's solid body there are tides. But we have them small, only half a meter the ocean rises here and there. 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 just warmed it up, these permanent deformations.

Question. Please tell me, what is our government doing to finance the development of science more?

V. G. Surdin. Oh I do not know. Well, for God's sake, I can't answer that 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 if there is information that an expedition to Mars is still being prepared.

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

Pay attention to the name of these missiles. Where are they with us, 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 the Greek synonym for Mars, so rockets are, generally speaking, made with an idea - made with an idea - and Martian expeditions. 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: why there, give money - we will fly to Mars by 2024. And now, even at the Institute of Medical and Biological Problems, such a ground flight to Mars is under way, the guys sit for 500 days in the bank, there are many, in general, nuances, it does not even look like a space flight. Well, okay, they sit and what they need, they will sit.

But - the question is: should man fly to Mars? A manned expedition with people costs at least 100 times more expensive than a good robust automatic vehicle. 100 times. On Mars - I had no opportunity today to tell about Mars at all - a lot of interesting and unexpected things were discovered. In my opinion, the most interesting thing: wells with a diameter of 100 to 200 m were found on Mars, no one knows what depth, the bottom is not visible. These are the most promising places for the search for life on Mars. Because it is warmer under the surface, there is more air pressure and, most importantly, humidity is higher. And if there is no Martian 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, the money of one manned expedition can launch a hundred automatic ones. And balloons, and all kinds of helicopters, and light gliders, and rovers, which the Americans have been running there for the sixth year, two rovers, two months later the heavy one flies there. It seems to me that sending an expedition with people is irrational.

Another argument against man's flight to Mars: we do not yet know what kind of life is on Mars, but we will already bring our own there. Until now, all the devices that landed on Mars have been sterilized, so that God forbid not to infect Mars with our microbes, otherwise you will not even figure out where which ones are. And you can't sterilize people. If they are there ... the spacesuit is not a closed system, it breathes, it throws it out ... in general, a man's flight to Mars is to infect Mars with our microbes. So what? Who needs it?

One more argument. The radiation hazard when flying to Mars is about 100 times higher than when flying to the Moon. Just calculations show that a person flies from Mars, even if without landing, just back and forth, without stopping, strongly ... with radiation sickness, in general, with leukemia. This ... is it necessary too? I remember our cosmonauts said: give us a one-way ticket. But who cares? In general, heroes are needed where they are needed. And for science, it seems to me, it is necessary to explore Mars by automatic means, this is going very well now, and we are now preparing the Mars-Phobos project for a flight to the Mars satellite. Maybe in the end it will be realized. It seems to me that this is a promising path.

And remember, in the 50-60s, all deep-sea research in our country was carried out by a man in a bathyscaphe, right? In the last 20 years, all oceanological science deeper than 1 km has been made by automatic machines. Nobody will send people there anymore, because it is difficult to ensure human life, the apparatus must be massive and expensive. Vending machines do it all easily and for less money. It seems to me that the situation is the same in astronautics: man's flights to orbit are now not really needed, and to the planets at all ... Well, PR, in general. But this is just my point of view. There are people who are "for" with both hands.

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

V. G. Surdin. To be honest, no traces of civilization have yet been found, although they are not excluded. If we wanted to somehow our own civilization, at least the memory of it or its achievements to preserve, well, in case, I don’t know, in the event of a nuclear war or, there, an asteroid falls to Earth, then the main thing that would be to do is to put our databases somewhere far away. To the moon, to the satellites of the planets, in general, farther from the Earth. And I think others would have done the same. But so far nothing has been found.

Question. These are these explicit rectangular objects ...

V. G. Surdin. Well, there were photographs of a sphinx-like face on the surface of Mars. Remember the "Sphinx on Mars"? Photographed - now "Mars reconnaissance orbiter" is flying around Mars, this is an American device with a sharpness of images up to 30 cm on the surface of Mars - photographed: the mountain turned out to be ordinary. There was a complex of pyramids like the pyramids in Giza, these are the same Cheops, these are also on Mars. They photographed: the mountains turned out to be, such old mountain remnants. Now we know Mars much better than the surface of the Earth, because we have 2/3 covered by the ocean, more forests, etc. Mars is clean, everything has been photographed to such details. When a rover walks on Mars, it is being watched and seen from Mars orbit. It's just that you can see the track from it and the rover itself, where it will climb. So there is no trace.

But these caves haunt me and other people. They were discovered recently, we tried to look into them. It's just a vertical well, the size of Luzhniki. It goes to an incomprehensible depth. This is where you need to look. It could be anything. 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 he will start working, but a lot of money has been spent, so he’s again ... The point is another thing. They don't want to launch it in winter. He eats up the energy of this whole district around Lake Geneva and in the summer it still suffices, and in the winter he will simply plant all of their substations. They will, of course. Probably in the fall, it will work great. The device is very interesting.

A remark from the audience. No, it's just that a lot of fears are catching up about him ...

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

Thanks. If there are no more questions, thanks, until next time.

This encyclopedia will be useful to everyone who is interested in the structure of the Universe and space physics, who by the nature of their activities is associated with space exploration. It provides detailed interpretations 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 sky maps and the latest data on the largest telescopes, planets and their satellites, 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 astronomers and even professional astronomers and physicists, since most of the data is for mid-2012.

Outstanding amateur astronomers.
In the XVII-XVIII centuries. the small staff of state observatories was mainly engaged in 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 XIX century. professional astronomers began to pay more attention to stellar astronomical and astrophysical research, but in these areas, science lovers were often in the forefront.

At the turn of the 18th and 19th centuries. the greatest amateur astronomer worked - the musician, conductor and composer William Herschel, whose faithful assistant and successor was his sister Carolina. From the point of view of amateur astronomy, the main merit of V. Herschel is 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 production of large telescopes-reflectors. This is what determined the main direction of amateur telescope construction for several centuries ahead.

Free download an e-book in a convenient format, watch and read:
Download the book Great Encyclopedia of Astronomy, Surdin V.G., 2012 - fileskachat.com, fast and free download.

• Encyclopedia for children, astronomy, Aksyonova M., Volodin V., Durlevich R., 2013
• Big Illustrated Encyclopedia, Planets and Constellations, Radelov S.Yu., 2014

The following tutorials and books.

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

After graduating from the Faculty of Physics of Moscow State University, Vladimir Georgievich has been working at the SAI for three decades. Research interests range from the origin and dynamic evolution of stellar systems to the evolution of the interstellar medium and the formation of stars and star clusters.

Vladimir Georgievich reads 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 is itself a science, while others are convinced that astrology is nothing more than a fortune-telling by the stars. The book tells how scientists relate to astrology, how they check astrological predictions and who of the great astronomers and to what extent was an astrologer.

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

Galaxies

The fourth book in the series "Astronomy and Astrophysics" contains an overview of modern concepts of giant stellar systems - galaxies. The history of the discovery of galaxies, their main types and classification systems are discussed. The fundamentals of the dynamics of stellar systems are given. The nearest galactic neighborhoods and works on the global study of the Galaxy are described in detail. Data on various types of populations of galaxies - stars, interstellar medium and dark matter - are presented. The features of active galaxies and quasars, as well as the evolution of views on the origin of galaxies, are described.

The book is aimed at undergraduate 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, Galileo Galilei marked the beginning of a new scientific era, stimulating the development of the exact sciences.

Astronomy was honored to lay 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 of the fantastic achievements of astronomy made in recent decades.

Stars

The book "Stars" from the series "Astronomy and Astrophysics" contains an overview of modern concepts of stars.

It tells about the names of the constellations and the names of the stars, about the possibility of observing them at night and during the day, about the main characteristics of the 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 outbreaks of novae and supernovae, are discussed.

Mars. Great confrontation

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

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

Elusive planet

A fascinating story of a specialist about how they seek and find new planets in the Universe.

Sometimes a happy accident decides everything, but more often - years of hard work, calculations and many hours of vigil at the telescope.

UFO. Astronomer's Notes

The UFO phenomenon is a multifaceted phenomenon. Journalists in search of sensations, and scientists in search of new natural phenomena, and the military, fearing the intrigues of the enemy, and simply inquisitive people, who are sure that "there is no smoke without fire", are interested in him.

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

Travel to the Moon

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

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

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

Exploration of distant planets

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

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

solar system

The second book of the series "Astronomy and Astrophysics" contains an overview of the current state of the study of planets and small bodies of the solar system.

The main results obtained in terrestrial and space planetary astronomy are discussed. The present-day data on the planets, their satellites, comets, asteroids and meteorites are presented. The presentation of the material is mainly focused on 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 various bodies: large planets, their satellites, as well as small bodies - asteroids and comets. Since 2006, a new subgroup has been introduced in the group of planets - dwarf planets ( dwarf planet), possessing the intrinsic qualities of planets (spheroidal shape, geological activity), but due to their low mass, they are not able to dominate in the vicinity of their orbit. Now the 8 most massive planets - from Mercury to Neptune - have been called simply planets ( planet), although in conversation astronomers often call them "large planets" for unambiguity to distinguish them from dwarf planets. The term "minor planet", which has been applied to asteroids for many years, is now deprecated in order to avoid confusion with dwarf planets.

In the area of ​​large planets, we see a clear division into two groups of 4 planets in each: the outer part of this area 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 outlined: Venus and Earth are extremely similar to each other in many physical parameters, and Mercury and Mars are inferior to them in mass by an order of magnitude and are almost devoid of an atmosphere (even Mars has it 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. Often they exceed in size and mass the dwarf planets, but at the same time they are under the control of gravity of much more massive bodies. We are talking about the Moon, Titan, the Galilean moons of Jupiter and the like. Therefore, it would be natural to introduce into the nomenclature of the solar system a new group for such "subordinate" objects of the planetary type, calling them "satellite planets". But this idea is still under discussion.

Let's go back to the terrestrial planets. Compared to giants, they are attractive in that they have a hard surface on which space probes can land. Since the 1970s. automatic stations and self-propelled vehicles of the USSR and the USA have repeatedly landed and successfully worked on the surfaces of Venus and Mars. Landings on Mercury have not yet taken place, since flights in the vicinity of the Sun and landing on a massive atmospheric body are technically very difficult.

Studying the terrestrial planets, astronomers do not forget the Earth itself. The analysis of images from space made it possible to understand a lot in the dynamics of the earth's atmosphere, in the structure of its upper layers (where planes and even balloons do not rise), in the processes taking place in its magnetosphere. Comparing the structure of the atmospheres of earth-like planets, one can understand a lot in 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 focuses on terrestrial planets, mainly their appearance and surface conditions.

The brightness of the planet. Albedo

Looking at the planet from afar, we can easily distinguish bodies with and without an atmosphere. The presence of the 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 seen if you arrange the planets in a row from completely cloudless (atmosphereless) to completely covered by clouds: Mercury, Mars, Earth, Venus. Stony atmosphereless bodies are similar to each other to almost complete indistinguishability: compare, for example, large-scale images of the Moon and Mercury. Even an experienced eye can hardly distinguish between the surfaces of these dark bodies, densely covered with meteorite craters. But the atmosphere gives any planet a unique look.

The presence or absence of an atmosphere on a planet is governed 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 streams. The moon lost its atmosphere (if at all) due to the low critical speed at the surface, and Mercury due to the high temperature and powerful solar wind. Mars, with almost the same gravity as Mercury, was able to preserve 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 are very similar in size, mass, and hence the average density. Their internal structure - crust, mantle, iron core - should also be similar, although there is no certainty about this yet, since there is no seismic and other geological data on the interior of Venus. Of course, we did not penetrate deeply into the bowels of the Earth: in most places - by 3-4 km, at some points - by 7-9 km, and only in one - by 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 are almost no such data. Detailed maps of the gravitational field are obtained only for the Moon; heat fluxes from the interior have been measured only on the Moon; seismometers so far also worked only on the Moon and (not very sensitive) on Mars.

Geologists still judge the inner life of planets by the features of their solid surface. For example, the absence of signs of lithospheric plates near 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 indicates the possibility of plate tectonics on Mars in the past, as well as tectonics of ice fields on Europa, the moon 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 not similar to each other can demonstrate similar geological phenomena.

Let's return to what is available to astronomers and other specialists for direct study, namely, to the surface of 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 Earth and from space probes has made it possible to study the surfaces of Venus and Titan through their light-opaque atmospheres. However, these works are of an episodic nature, and systematic studies of planets are still carried out with optical instruments. And more importantly, optical radiation from the Sun is 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 planet's surface.

The brightness of a planet's surface depends on its distance from the Sun, as well as on 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 star 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 a 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 in the frame at the same time. This image was taken by the Galileo space probe as it flew past Earth on its way to Jupiter. See how much the Moon is darker than Earth and in general darker than any planet with an atmosphere. This is a general rule: non-atmospheric bodies are very dark. The fact is that under the influence of cosmic radiation, any solid matter gradually darkens.

The statement that the surface of the moon is dark usually causes confusion: at first glance, the lunar disk looks very bright, cloudless at 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 reflectance of light. Albedo equal to zero is absolute blackness, complete absorption of light. Albedo equal to one is total reflection. Physicists and astronomers have several different approaches to determining albedo. It is clear that the brightness of the 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 stepped on with your boot has a completely different value. And the dependence on orientation is easy to demonstrate with a mirror, letting in sunbeams. The exact definition of the albedo of various types is given in the chapter “Quick Reference Guide” (p. 265). Familiar surfaces with different albedos are concrete and asphalt. Illuminated with the same streams of light, they demonstrate different visual brightness: freshly washed asphalt has an albedo of about 10%, while clean concrete has 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 solid cloud cover of Venus reflects 77% of the light. Our Moon is one of the darkest bodies, reflecting on average about 11% of the 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 light bodies: Saturn's moon Enceladus reflects 81% of visible light, and its geometric albedo is simply fantastic - 138%, that is, it is brighter than a perfectly white disk of the same cross section. It’s even difficult to understand how he succeeds. Pure snow on Earth reflects light even worse; what kind of snow lies on the surface of a 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 losses. There are three known heat exchange mechanisms: radiation, heat conduction and convection. The last two processes require direct contact with the environment, therefore, in the cosmic vacuum, the first mechanism, radiation, becomes the most important and, in fact, the only one. For designers of space technology, this creates considerable problems. They have to take into account several sources of heat: the sun, the planet (especially in low orbits) and the internal assemblies of the spacecraft itself. And there is only one way to release heat - radiation from the surface of the apparatus. To maintain the balance of heat fluxes, space technology designers regulate the effective albedo of the spacecraft 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 of.

But for the first time this problem was encountered in the first third of the XX century. the creators of high-altitude balloons - the so-called stratospheric balloons. In those years, they still did not know how to create complex systems for thermoregulation of a sealed gondola, therefore, they were limited to a simple selection of the albedo of its outer surface. The history of the first flights into the stratosphere tells how sensitive the body temperature is to its albedo. The Swiss Auguste Piccard painted the gondola 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 with one side 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 in 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. Inside it became minus 16 ° C.

American designers of stratospheric balloon Explorer took into account the experience of Picard and adopted a compromise option: they painted the upper part of the capsule white, and the lower one black. The idea was that the upper half of the sphere would reflect solar radiation and 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 aluminum capsules with a layer of felt. As practice has shown, this solution 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, converting it into its own infrared radiation, thereby supporting the water cycle in nature, storing it as a result of photosynthesis in biomass, oil, coal, gas. The moon absorbs almost all sunlight, "ineptly" converting it into high-entropy infrared radiation and thereby maintaining its fairly high temperature. But Enceladus, with its perfectly white surface, proudly repels almost all sunlight from itself, for which it pays with a monstrously low surface temperature: an average of about −200 ° C, and in some places up to −240 ° C. However, this moon - "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 keeps 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 hand, to keep the energy of radiation that has passed through atmosphere to the surface of the planet.

The greenhouse effect and the planet's climate

Depending on how far from the Sun the planet is and what proportion of sunlight it absorbs, temperature conditions are formed on the planet's surface, its climate. 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 "one-humped", almost Planckian curve, in which the position of the maximum depends on the temperature of the star's surface. Unlike a star, the spectrum of the planet has two "humps": it reflects part of the starlight in the optical range, and absorbs and re-radiates the other part in the infrared range. The relative area under these two humps is precisely determined by the degree of light reflection, that is, the 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 the sunlight and absorbs only about 20%, and Mercury reflects almost nothing, but absorbs everything. Moreover, Venus is farther from the Sun than Mercury; per unit of its cloudy surface, 3.4 times less sunlight falls. Taking into account the difference in albedo, each square meter of the solid surface of Mercury receives almost 16 times more solar heat than the same area on Venus. And nevertheless, on the entire solid surface of Venus, hellish conditions - a huge temperature (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, close to the Sun and willingly absorbing its rays, heated to room temperature, while Venus, farther from the Sun and actively reflecting its rays, is hot as a furnace? How will physics explain this?

The Earth's atmosphere is almost transparent: it allows 80% of the incoming sunlight to pass through. As a result of convection, air cannot "escape" into space - the planet does not let it go. This means that it can be cooled only in the form of infrared radiation. And if the infrared radiation remains blocked, then it heats up those layers of the atmosphere that do not release it. These layers themselves become a source of heat and partly direct it back to the surface. Some part of the radiation goes into space, but most of it returns to the Earth's surface 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 the infrared rays will escape into space. The balance of heat fluxes is established, but at a higher temperature than it could be in the absence of the atmosphere. This is the greenhouse effect.

In our life, we are often faced with 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 radiant and convective heat removal is reduced in them. An example of a clear frosty night is much closer to the described effect. With dry air and cloudless skies (for example, in the desert), the earth cools down quickly after sunset, and humid air and clouds smooth out daily temperature fluctuations. Unfortunately, this effect is well known to astronomers: clear starry nights are especially cold, which makes working at the telescope very uncomfortable. Returning to fig. 4.8, we will see the reason: it is steam NS Water in the atmosphere is the main obstacle to heat-carrying infrared radiation.

The moon has no atmosphere, which means there is no greenhouse effect either. On its surface, thermodynamic equilibrium is established in an explicit form, there is no exchange of radiation between the atmosphere and a solid surface. Mars has a thin atmosphere, but still its greenhouse effect adds its 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 across the globe, but it would be −25 ° C. All oceans would freeze, the surface of the Earth would turn white from snow, the albedo would rise, and the temperature would drop even lower. In general - a terrible thing! It's good that the greenhouse effect in our atmosphere works and keeps us warm. 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 embarked on a detailed study of other planets, mainly limiting ourselves to observing their surfaces. How important is information about the appearance of the planet for science? What value can the image of its surface tell us? If it is a gaseous 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, we have almost no information about the planet itself. The cloudy atmosphere, as geologists say, is a super-young surface: today it is like this, and 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 they 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 what picture our ancestors could have seen, we will never know. Thus, looking from the outside at planets with a dense atmosphere, we cannot judge their past, since we see only a changeable cloud layer. A completely different matter is the Moon or Mercury, whose surfaces keep traces of meteorite bombardments and geological processes that have taken place over the past billions of years.

And such bombing of giant planets practically leaves no traces. One of these events took place at the end of the twentieth century right in front of astronomers. It's about a comet Shoemakers-Levy-9... In 1993, not far from Jupiter a strange chain of two dozen small comets was seen. 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. The astronomers did not see the episode of the comet's disintegration itself, but only caught the moment when the chain of cometary debris was moving away from Jupiter like a "train". If the disintegration had not occurred, then the comet, having flown up to 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 expenditure 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 periapsis 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 tremendous. Each "fragment" of the cometary nucleus is a block of ice 1–1.5 km in size. They in turn flew into the atmosphere of a giant planet at a speed of 60 km / s (the second cosmic speed for Jupiter), having a specific kinetic energy (60/11) 2 = 30 times greater than if it was a collision with the Earth. Astronomers with great interest, while safe on Earth, observed the cosmic catastrophe on Jupiter. Unfortunately, fragments of the comet hit Jupiter from the side that was not visible from Earth at that moment. Fortunately, just at this time on the way to Jupiter there was a space probe "Galileo", he saw these episodes and showed them to us. Due to the fast daily rotation of Jupiter, the collision areas in a few hours became accessible to ground-based telescopes, and, which is especially valuable, to near-Earth telescopes, such as the Hubble Space Telescope. This was very useful, since each block, crashing into Jupiter's atmosphere, caused a colossal explosion, destroying the upper cloud layer and creating for a while a window of sight deep into the Jupiter atmosphere. So, thanks to the cometary 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.

It's a different matter - Earth... Meteorite scars remain on our planet for a long time. Before you 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 fine geological methods. They are not visible from above.

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

On a surface The 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 space bombing. On the reverse side is an even more useful picture for science. It seems that for some reason, especially large bodies never fell there, or, falling, they could not break through the lunar crust, which on the back side is twice as thick as on the visible one. 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 the younger ones destroy those that formed earlier. Saturation has taken place: the Moon can no longer become more multiplied than it is; craters everywhere. And this is a wonderful chronicle of the history of the solar system: several episodes of active crater formation have been identified, 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 hit the planets during this 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 only on the surface from which samples have been collected so far.

Mercury outwardly similar to the moon, because, like it, it has no 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 holds 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 than on the Moon.

Mercury is about one and a half times the size of the Moon, but its mass is 4.5 times larger 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 (at the Earth - only 55%), the volume - 45% of the volume of the planet (at the Earth - 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 metal core, Mercury could surpass the Earth in its average density, if not for the small force of 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 bowels as much as the bowels of the Earth have compacted, in which even the silicate mantle has a density of about 5 g / cm 3.

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

For the first time to Mercury went in 1973 "Mariner 10" (NASA). He first approached Venus, slowed down in its gravitational field and then passed near Mercury three times in 1974-1975. Since all three meetings took place in the same region of the planet's orbit, and its diurnal rotation is synchronized with the orbital, all three times the probe photographed the same hemisphere of Mercury illuminated by the Sun.

For the next several decades, there were no flights to Mercury. And only in 2004 was it possible to launch the second apparatus - MESSENGER ( Mercury Surface, Space Environment, Geochemistry, and Ranging; NASA). After performing several gravitational maneuvers near the Earth, Venus (twice) and Mercury (three times), the probe entered orbit around Mercury in 2011 and conducted research on 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 flux of sunlight there is almost 7 times greater. Without a special "sun umbrella", the electronic filling of the probe would overheat. Now the third expedition to Mercury is being prepared under the name 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 flyby near Venus and six near Mercury. In addition to a detailed study of the planet's surface and its gravitational field, a detailed study of the magnetosphere and the magnetic field of Mercury, which is a mystery to scientists, is planned. Although Mercury rotates very slowly, and its metal core should have cooled and solidified a long time ago, the planet has a dipole magnetic field, which is 100 times inferior in strength to that of the Earth, but still supports the magnetosphere around the planet. The modern theory of magnetic field generation in celestial bodies, the so-called theory of a turbulent dynamo, requires a layer of a liquid conductor of electricity in the bowels of the planet (this is the outer part of the iron core of the Earth) and relatively fast rotation. For what reason the core of Mercury is still 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 the axis. Generally speaking, astronomers have been familiar with synchronous motion for a long time: our Moon rotates synchronously around its axis and revolves around the Earth, the periods of these two motions are the same, that is, they are in a 1: 1 ratio. And on other planets, some satellites show the same feature. This is the result of the tidal effect.

To trace the movement of Mercury, put an arrow on its surface (Fig. 4.20). It can be seen that in one revolution around the Sun, that is, in one Mercurian year, the planet turned around its axis exactly one and a half times. During this time, the day in the area of ​​the arrow changed to night, half a sunny day passed. One more annual turnover - and in the area of ​​the arrow the day comes again, one solar day has expired. Thus, on Mercury, a solar day lasts two Mercury years.

We will talk in detail about the tides in Chapter 6. It was as a result of the tidal influence from the Earth that the Moon synchronized its two motions - axial rotation and orbital rotation. The Earth has a very strong influence on the Moon: it stretched its shape, stabilized 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 (the extent of this "almost" we discussed in Chapter 1). Therefore, the tidal effect changes little 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, then approaching the star, then moving away from it. When it is far away, in the region of the aphelion of the orbit, the tidal influence of the Sun weakens, since it depends on the distance as 1 / R 3. When Mercury approaches the Sun, the tides act much stronger, therefore, only in the perihelion region does Mercury effectively synchronize its two movements - diurnal and orbital. Kepler's second law says that the angular velocity of orbital motion is maximum at the point of perihelion. It is there that the "tidal capture" and synchronization of the angular velocities of Mercury - diurnal and orbital - take place. At the point of perihelion, 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 decreasing the angular velocity of its 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 pictures of Mercury appeared, showed them to each other and asked: "Come on, guess, is it the Moon or Mercury?" It is really difficult to guess: both there and there is a surface beaten by meteorites. But, of course, there are some peculiarities. Although there are no large lava seas on Mercury, its surface is heterogeneous: there are areas that are older and younger (the basis for this is the count of meteorite craters). Mercury differs from the Moon by the presence of characteristic ledges and folds on the surface, which have arisen as a result of the compression of the planet during the cooling of its huge metal core.

Temperature drops on the surface of Mercury are greater than on the Moon: in the daytime at the equator + 430 ° C, and at night -173 ° C. But the soil of Mercury serves as a good heat insulator, therefore, at a depth of about 1 m, daily (or two-year?) Temperature drops are no longer felt. So if you fly to Mercury, the first thing to do is to dig a dugout. It will be about + 70 ° C at the equator: it is hot. But in the region of the geographic poles, the dugout will be about -70 ° C. So you can easily find the geographical latitude at which it 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 the deposits of water ice were discovered, which were previously "groped" by radars from the Earth, and then confirmed by the instruments of the MESSENGER space probe. The origin of this ice is still under discussion. Its sources can be both comets and steam escaping from the bowels of the planet. NS water.

Mercury has a color, although it looks dark gray to the eye. 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 - the Plain of Heat ( Caloris basin) with a diameter of 1550 km. This is a trail from the impact of an asteroid with a diameter of at least 100 km, which almost split the small planet. It happened about 3.8 billion years ago, during the so-called "late heavy bombardment" ( Late Heavy Bombardment), when the number of asteroids and comets in orbits crossing the orbits of the terrestrial planets increased for not completely clear reasons.

When Mariner 10 photographed the Plain of Heat in 1974, we did not yet know what happened on the opposite side of Mercury after this terrible blow. It is clear that if the ball is hit, then sound and surface waves are excited, which propagate symmetrically, pass through the "equator" and collect at an antipode point, diametrically opposite to the point of impact. The perturbation there contracts to a point, and the amplitude of seismic vibrations increases rapidly. This is similar to how the cattle drivers snap their whip: the energy and momentum of the wave is practically conserved, and the thickness of the whip tends to zero, so the oscillation 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 to be: there was a vast hilly area with a grooved surface, although I expected that there would be an antipode crater. It seemed to me that when a seismic wave collapsed, a phenomenon would occur, "mirroring" the fall of the asteroid. 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 up. This did not happen on Mercury, and we now understand why: its bowels turned out to be inhomogeneous, and precise focusing of the waves did not happen.

In general, the relief of Mercury is smoother than that of the Moon. For example, the walls of Mercury craters are not that high. The reason for this is likely due to the greater force of gravity and the warmer and softer bowels of Mercury.

Venus- the second planet from the Sun and the most mysterious of the terrestrial planets. It is not clear what is the origin of its very dense atmosphere, almost entirely composed of carbon dioxide (96.5%) and nitrogen (3.5%) and providing a powerful greenhouse effect. It is not clear why Venus rotates so slowly around its axis - 244 times slower than 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 super rotation 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 the 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 against 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 works. The question is: 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 are less compact there. In fact, there are only two of them: one in the northern hemisphere, the other in the southern. Each of them "winds" from the equator to its own pole.

The upper layers of the Venusian atmosphere were studied in detail by flyby (in the process of gravitational maneuver) and orbital probes - American, Soviet, European and Japanese. The devices of the Venera series were launched there by Soviet engineers for several decades, and this was our most successful breakthrough in the field of planetary exploration. The main task was to land the descent vehicle on the surface to see what was 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 XX 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 Earth-like world. For the same reason, the first landing craft of Venusian probes were made not very strong, unable to withstand high pressure. And they died, descending in the atmosphere, one by one. Then their hulls began to be made stronger, with the expectation of a pressure of 20 atmospheres, but this was not enough. Then the designers, "biting the bit", created a titanium probe that can withstand a pressure of 180 atm. And he safely sat down on the surface ("Venera-7", 1970). Note that not every submarine can withstand such pressure, which reigns at a depth of about 2 km in the ocean. It turned out that at the surface of Venus, the pressure does not drop below 92 atm (9.3 MPa, 93 bar), and the temperature is 464 ° C.

It was in 1970 that the dream of a hospitable Venus, similar to the Earth of the Carboniferous period, was finally finished. on the surface of Venus have become a routine operation, however, it is not possible to work there for a long time: after 1–2 hours, the interior of the apparatus heats up and the electronics fail.

The first artificial satellites appeared near Venus in 1975 ("Venera-9 and -10"). On the whole, the work on the surface of Venus of the Venera-9 ... -14 descent vehicles (1975-1981) turned out to be extremely successful, which studied both the atmosphere and the surface of the planet at the landing site, who even managed 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 photographic panoramas of the landing sites transmitted by them, at 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 arouse great interest among planetary scientists. They continue to be processed and from time to time new parts are found on them.

American astronautics also made a significant contribution to the study of Venus in those years. Flying vehicles "Mariner-5 and -10" studied the upper atmosphere. Pioneer Venera 1 (1978) became the first American satellite of Venus and carried out radar measurements. And "Pioneer-Venus-2" (1978) sent 4 descent vehicles into the planet's atmosphere: one large (315 kg) with a parachute to the equatorial region of the day hemisphere and three small (90 kg each) without parachutes - to middle latitudes and north of the daytime hemisphere as well as the nighttime hemisphere. None of them was designed to work on the surface, but one of the small devices landed safely (without a parachute!) And worked on the surface for over an hour. This case allows you to feel how high the density of the atmosphere at the surface of Venus. The atmosphere of Venus is almost 100 times more massive than 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 than the density of liquid water.

It was not easy to create durable scientific probes that can 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 get them to withstand the ambient temperature (+ 464 ° C) in such dense air. The heat flow through the case is colossal, so even the most reliable devices worked for no more than two hours. In order to descend to the surface as soon as possible and prolong the work there, the Venera dropped a parachute during landing and continued descent, braking only with a small shield on their hull. The impact on the surface was softened by a special damping device - a landing support. The design was so successful that Venera-9 landed on a 35 ° slope without any problems and worked normally.

Such panoramas of Venus (Fig. 4.27) were published immediately after they were received. A curious event can be noticed here. During the descent, each camera was protected by a polyurethane cover, which, after landing, shot back and fell down. In the top picture, this white semi-circular cover is visible at the landing post. Where is she in the bottom picture? Lies to the left of the center. It was into it, straightening, that the device for measuring the mechanical properties of the soil stuck his probe. By measuring its hardness, he confirmed that it was polyurethane. The device, so to speak, was tested in the field. The probability of this sad event was close to zero, but it happened!

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

In October 1975, the Venera-9 and -10 lander through their orbital blocks transmitted to the 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 oddly distorted due to the rotation of the shooting direction. These images were obtained with a telephotometer (optical-mechanical scanner), whose “gaze” slowly moved from the horizon to the “feet” of the lander and then to another horizon: a 180 ° sweep was obtained. Two telephotometers on opposite sides of the device were supposed to give a full panorama. But the lens caps did not always open. For example, none of the four opened on Venera-11 and -12.

One of the most beautiful experiments in the exploration of Venus was carried out with the probes "VeGa-1 and -2" (1985). Their name is deciphered as "Venus - Halley", because after the separation of the descent vehicles directed to the surface of Venus, the flight parts of the probes left to investigate the nucleus of Halley's comet and for the first time successfully did it. The landing craft were also not quite ordinary: the main part of the apparatus landed on the surface, and when descending, a balloon made by French engineers 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 the Earth , illumination and visibility in the 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.

Photos from the landing sites show only small patches of the Venusian surface. Is it possible to see all of Venus through the clouds? Can! The radar sees through the clouds. To Venus flew two Soviet satellites with side-looking radars and one American. Based on their observations, radio maps of Venus were compiled with a very high resolution. It is difficult to demonstrate it on a general map, but it is clearly visible on separate map fragments. The color on the radio maps shows the levels: cyan and blue are the 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 well-known geologist, academician Nikolai Leontievich 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”, “Science First Hand” No. 3 (69), 2016).

There are no reliable facts about the interior of Venus, about its internal structure, since seismic studies have 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 about the distribution of density with depth. So far, theoretical concepts are based on the similarity of Venus with 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. Together 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 can explain the absence of a magnetic field in it. All this looks logical, but requires experimental verification.

By the way, oh 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 on the basis of school knowledge. But in connection with the study of other planets, I will note that the bowels of our planet are not fully understood by us. Almost every year, major discoveries in geology take place, sometimes even new layers are found in the bowels of the Earth, but we still do not know the exact 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 - that it is more than 6300 K. These are the results of theoretical calculations, which include not entirely reliable parameters describing the properties of matter at a temperature of thousands of Kelvin and a pressure of millions of bar. Until these properties are reliably studied in the laboratory, we will not get exact knowledge about the interior of the Earth.

The uniqueness of the Earth among planets like it 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, it seems now, in the bowels of the planet there must be a liquid electrically conductive layer engulfed in convective motion, and a fast diurnal rotation, providing the Coriolis force. Only under these conditions is the dynamo mechanism activated, which amplifies the magnetic field. Venus practically does not rotate, so it has no magnetic field. The iron core of small Mars has long cooled and hardened, so it is also devoid of a magnetic field. Mercury, it would seem, rotates very slowly and should have cooled down before Mars, but it has a quite tangible dipole magnetic field with an intensity of 100 times weaker than Earth's. Paradox! The tidal influence of the Sun is now believed to be responsible for keeping the iron core of Mercury in a molten state. Billions of years will pass, the iron core of the Earth will cool and solidify, depriving our planet of magnetic protection from the solar wind. And the only solid planet with a magnetic field will remain, oddly enough, Mercury.

From the point of view of the terrestrial observer, at the moment of opposition, Mars is on one side of the Earth, and the Sun is 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. The Earth makes its revolution around the Sun in a year, and Mars in 1.88 years, so the average time between oppositions takes a little more than two years. The last opposition of Mars was observed in 2016, however, it was not particularly close. The orbit of Mars is noticeably elliptical, so the closest approach of the Earth to it occurs when Mars is in the region of 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, occurring every 15-17 years, our planets approach each other by less than 60 million km. This will be in 2018. And the super-violent confrontation took place in 2003: then there was only 55.8 million km to Mars. In this regard, a new term was born - "the greatest oppositions of Mars": such approaches are now considered to be less than 56 million km. They occur 1-2 times a century, but in this century there will be even three of them - wait for 2050 and 2082.

But even in moments of great confrontation, little is visible from Earth on Mars through a telescope. 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, only a small pink "drop", but the experienced eye of an astronomer sees more through the same telescope. Astronomers noticed the polar cap long ago, centuries ago. And also - dark and light areas. The dark ones are traditionally called seas, and the light ones are called continents.

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

Observations of details of 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 had to be given a name, Schiaparelli called them "channels" ( canali), meaning by this sea straits, and by no means man-made structures. He believed that water actually flows through these channels in the circumpolar 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 rule out the presence of life on Mars, possibly even intelligent.

However, the idea of ​​an artificial system of irrigation canals on Mars began to gain ground in other countries. This was partly due to the fact that the Italian canali was introduced in English as canal(man-made waterway), not how channel(natural sea strait). And in Russian, the word "channel" means an artificial structure. The idea of ​​the Martians then captivated many, and not only writers (remember HG Wells with his War of the Worlds, 1897), but also researchers. The most famous of these was Percival Lovell. The American received an excellent education at Harvard, mastering mathematics, astronomy, and the humanities in equal measure. But as a 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 interested in Mars and believed in the existence of life and civilization on it. In general, he abandoned all other affairs and began to study the Red Planet.

With money from his wealthy family, Lovell built an observatory and began painting 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 Lovell Observatory maps of the Martian canals were the most detailed. In addition, being a good writer, Lovell wrote some of the most entertaining books - Mars and its canals (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 the Martians. Winter - the polar cap is huge, and the channels are not visible. Summer - the cap melted, the water started flowing, the channels appeared. They became visible from afar, as plants turned green along the banks of the canals. Earnestly?

It should be admitted that the story with the Martian channels has not received an exhaustive explanation. There are old drawings with channels and modern photographs - without them (Fig. 4.44). Where are the channels?

What was it? A conspiracy of astronomers? Mass insanity? Self-hypnosis? It is difficult to blame the scientists who gave their lives to science for this. Perhaps the answer to this story lies ahead.

And today we study Mars, as a rule, not with 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). Kepler's third law makes it easy to calculate the duration of such a flight. Due to the large 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 this requires only a powerful launch vehicle and a comfortable spacecraft. No one has yet powerful enough carriers, but American, Russian and Chinese engineers are working on them. There is no doubt that such a rocket in the coming years will be created by state enterprises (for example, our new Angara rocket in its most powerful version) or by private companies (Elon Musk - why not).

Is there a ship in which astronauts will spend many months en route to Mars? There is no such thing yet. All existing ("Union", "Shenzhou") and even undergoing tests ( Dragon v2, CST-100, Orion) - very cramped and suitable only for a flight to the moon, where it is only three days' journey. 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 a flight to Mars will soon appear. So what's the problem? In a man! In fig. 4.45 shows the annual dose of human exposure to background radiation in different places - at sea level, in the stratosphere, in near-earth orbit and in open space. The unit of measurement is rem (biological equivalent of an X-ray). We are constantly exposed to the natural radioactivity of the earth, streams of cosmic particles or artificially created radioactivity. At the surface of the Earth, the background is weak: we are protected by covering the lower hemisphere, the magnetosphere and the atmosphere of the planet, as well as its body. In low-earth orbit, where the ISS cosmonauts work, the atmosphere no longer helps, so the background radiation increases hundreds of times. In open space, it is several times higher. This significantly limits the duration of a person's safe stay in space. Note that workers in the nuclear industry are prohibited from receiving more than 5 rem per year - this is almost safe for health. Astronauts 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 at best (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 man's flight to Mars.

Can astronauts be protected from radiation? Theoretically, you can. On Earth, we are protected by the atmosphere, the thickness of which, in terms of the amount of matter 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 and even promising rocket.

Well, let's say there are volunteers who are ready to risk their health and go to Mars in one direction without radiation protection. Will they be able to work there after landing? Can they be expected to complete the task? Remember how cosmonauts, after spending six months on the ISS, feel right after landing on earth: they are carried in their arms, put on a stretcher, and for two or three weeks they rehabilitate, restoring bone strength and muscle strength. And on Mars, no one can carry them in their arms. There it will be necessary to independently go out and work in heavy void spacesuits, as 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 force of gravity there is 1/6 of the earth, and after three days of flight to the Moon, the muscles do not have time to weaken. On Mars, the astronauts will arrive after spending many months in zero gravity and radiation, and the force of gravity on Mars is two and a half times greater than the moon. In addition, on the very surface of Mars, 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 a fantasy, very beautiful, but unreal.

Some options for radiation protection in interplanetary flight

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

What the robots have learned about Mars will be in the next lecture.