In connection with the current "Venusian" excitement, I decided to post a compilation of two chapters "The Mystery of the Clouds" and "Romantics of the XXth century from pragmatists of the XXI century" from his book "Venus. Indomitable planet ".
We learned a lot about Venus in the 20th century. It has finally become known what our space companion looks like: detailed maps of its surface have been built, panoramas of Venusian landscapes have been obtained. But, perhaps, the readers have questions: “Why was all this? Why did countries spend hundreds of millions of rubles or dollars? Just to get some photos from another planet? And this is the result of the whole program? "
To begin with, one should not forget that the main reason for the flights to Venus was still not so much pure science as the romance of the pioneers. Venus and Mars at the beginning of the 60s of the twentieth century were seen as new continents, where the discoverers had not yet sailed, and then it seemed that it was necessary to explore Venus and Mars just so that the pioneer colonizers of these planets would have as few problems as possible. And this opinion was prevalent both in the USSR and in the USA.
For example, you can look at the Soviet schedule (Fig. 180) of the exploration of Mars and Venus. Moreover, this schedule is not just someone's fantasy - no, it illustrates a real plan adopted by the USSR leadership in 1960. A manned flight to Venus seemed like a perfectly logical step after AMC. And in general, despite the problems with financing and the violation of the deadlines, work in this direction was carried out. Moreover: the manned flight was discussed in all seriousness at the official press conference dedicated to the results of the Venera-4 operation. Keldysh then recognized this development of events as quite real.
I would just like to remind you that this happened before the joint processing of information from Venus-4 and Mariner-5 showed the real picture on the Planet of Storms. So, perhaps this was the last official discussion of this issue.
Alas, very soon it became obvious that man would not be able to land on the surface of Venus. Temperatures under 500 ° C and a pressure of about 100 atm did not give the person a single chance. But the question immediately arose: why, in fact, land on the planet itself? Just because we are used to living on the surface of the Earth? What kind of superficial chauvinism? Let's say, at an altitude of 53 km from the surface of Venus, the temperature is 30 degrees, and the pressure is 0.6 atm (table 1). With such parameters, a person may well live. There will also be an atmosphere around from carbon dioxide, from which, with a certain desire, you can get oxygen. There is little water, but with the correct formulation of the problem, it is quite realistic for atmospheric colonists to manage even with such a concentration. The main thing is to let as much atmosphere as possible through the water absorber.
Moreover, the hypothesis about the possibility of life on Venus did not die at all, as one might think, even after the direct experiment on Venus and the death of the ionospheric theory. An example would be several articles published in 1968 and based on data from Venera 4 and Mariner 5. Moreover, they were not published in the yellow papers at all. No, these were serious and respected journals: Science News, Nature, information from which was presented in the journal of the USSR Academy of Sciences "Nature".
For example, Professor Harold Morowitz (one of NASA's leading biophysicists) suggested that life on Venus exists, but not on the surface, but in the atmosphere. The cloud layer has just the right temperature and pressure range that is comfortable for life. There is enough carbon dioxide, solar radiation and water - in other words, all the necessary components for photosynthesis, he stated.
Morowitz believed that organisms were shaped like a floating bubble filled with hydrogen. They could receive molecular hydrogen from water during photosynthesis - such organisms are known under terrestrial conditions. According to calculations, their size could be about 4 cm in diameter or more.
“Perhaps life on Venus,” Morowitz wrote, “originated on the surface when conditions were mild. When conditions changed, organisms had to look for suitable conditions in the clouds. "
In general, the harsh conditions on the surface slightly embarrassed the romantics, and in the late 60s, quite a few projects of Venusian atmospheric cities and settlements managed to appear. And there was something really unearthly in such atmospheric cities. Alas, it was soon possible to find out that sulfuric acid plays an important role in the atmosphere of Venus, and this discovery turned out to be much more unpleasant. In fact, it did not abolish the idea of floating settlements, but made them much more difficult to implement.
However, human thought does not stand still. Almost immediately another idea appeared: if it is difficult for humanity to adapt to the conditions on Venus, Venus needs to be adapted for humans. It was even more difficult, but it opened up amazing possibilities. If you look into the future and start fantasizing, then Venus is seen as a very effective semi-finished product for creating a planet similar to the Earth. There is even a special word for such a process - terraforming. In this matter, the Morning Star is much better than Mars, since the latter, even with the most optimistic plans, will not be able to hold for a long time a dense atmosphere, similar to the earth, in which a person could do without a spacesuit: Mars has too little mass for this.
Venus looks preferable for these purposes. It contains all the elements from which you can create the earth's atmosphere and hydrosphere. There is no reason to believe that the current Venusian parameters are the only ones possible. The very fact of a higher temperature on the surface of Venus than on Mercury, which is much closer to the Sun, hints that, theoretically, completely different characteristics of conditions can exist with the same solar constant. It is quite possible not only to increase, but also to lower the temperature - this is evidenced, for example, by earthly calculations of the consequences of a nuclear winter. According to these models, the soot from city fires entering the stratosphere should lead to a decrease in the temperature of the Earth's surface by tens of degrees.
So bringing the conditions on Venus to the usual terrestrial conditions should not be considered a too loose assumption.
How can this be done? So far, only one path can be named. Back in the 60s, Carl Sagan proposed to throw microorganisms on Venus to recycle its atmosphere (Figure below). True, he did not know about sulfuric acid then, but its presence cannot be an obstacle. Even on Earth there are so-called sulfate-reducing bacteria that feel good in sulfuric acid and use it in their life cycle.
Of course, such microorganisms for the possible restructuring of the atmosphere of Venus will need to be created, and there is no experience in the implementation of projects of this kind on Earth. It is also obvious that this will be a very large-scale project that does not have even the slightest analogue in the history of mankind. But if it is ever realized, then humanity, in fact, will create with its own hands another planet suitable for life.
From a safety point of view, only the issue of radiation protection in the absence of a magnetic field is not clear. And terraforming engineers may well be thoroughly tormented by solving this problem.
But this is in the distant future. Only our great-great-great-grandchildren will probably be able to see the blue sky and white Venusian clouds.
What is the point of studying the Planet of Storms now? Or is it safe to say that our heavenly companion no longer has white spots?
In fact, there are many more of them than it seems at first glance. We do not know anything about the characteristics of the planet's core, we only have preliminary models. There are many facts that Venus is now active in a geological sense. One of the images of the Magellan is supposed to show active volcanoes. Cyclical changes in sulfur compounds were found among the data from Pioneer-Venus, which are possibly associated with volcanic activity, and the Venera-13 seismometer recorded two small shocks. And more recently, "Venus-Express" transmitted a heat map of the Venus region, which shows an active volcano (Fig. 168). But based on these data, it is impossible to build a detailed diagram of the interior of the planet.
To deal with this issue, an engine level station is desirable. And best of all - a veneer rover at its base.
There are also questions about the atmosphere of Venus. Yes, of course, one of the main elements of the cloud layer is sulfuric acid, this fact is beyond doubt. But with all this, it is guaranteed to be fixed only in a small range of heights. The exact concentration depending on the altitude, and most importantly, what else is in the atmosphere, besides it, is not yet known. And the chemistry of the atmosphere of Venus is clearly much more complicated than that of the earth. In addition to sulfur compounds, there are compounds of chlorine, phosphorus, and possibly also mercury.
In a sense, delivering a sample of Venus' atmosphere is somewhat more interesting than delivering its soil. And also easier. And a long-term balloon probe, similar to that developed in the early Vega version or for the BVS project, would be very interesting. Alas, no one is planning such missions yet.
Also, one cannot fail to mention the version that life still exists on our neighbor. In 2012, the scientific world was stirred up by the article "Possible detection of life on the planet Venus." Its author is the famous planetary scientist Leonid Ksanfomality, and it was published in the "Reports of the Academy of Sciences". In an article on the analysis of Venus panoramas, the author concludes that some details of the images may be evidence of the presence and activity of living beings. Moreover, in his opinion, Venera-9 was the cause of the first earthly aggression: during landing, it crushed a Venusian creature, and it, crawling away from the station, left a “bloody” trail.
The article is really interesting to read, but, according to the author of the book, the examples given are still not evidence of the existence of Venusian life. The panoramas were analyzed at the resolution limit of telephotometers; many analyzed objects are literally a few pixels in size. And among scientists there is such a rule: "Serious statements require serious evidence." Life on Venus is a really serious discovery, and more weighty arguments are needed for evidence than an analysis of counted pixels in several panoramas. However, perhaps the most interesting questions and discoveries concern not the present of Venus, but its past.
Yes, Venus is now a red-hot hell. Being closer to the Sun, Venus receives almost twice as much heat as the Earth, which is one of the reasons for both the high temperature on its surface and high pressure.
But let's fast forward to the past. Our Sun is an ordinary star, and in its development it went through all the changes through which other stars pass, and these changes have already been studied quite well by us. In particular, at the moment the luminosity of the Sun is growing. In other words, there used to be a time when Venus received as much solar radiation as the Earth is receiving now. Accordingly, the conditions on its surface were very similar to those on Earth. There, perhaps, the oceans splashed, in which, most likely, there was life, dinosaurs walked on land, and lizards flew in the clouds. Then, with the increase in temperature, the oceans dried up, sedimentary rocks like limestone, after annealing, released CO2 into the atmosphere.
According to this version, even earthly life can be the heir to Venusian life! Back in the early twentieth century, the Swedish scientist Svante Arrhenius calculated that bacterial spores are quite capable of flying from one planet to another under the pressure of sunlight. But this spread can only be away from the Sun. That is, disputes would not have been able to fly from Earth to Venus, but the path from Venus to Earth is already quite possible.
The fact that earlier the neighboring planet had a completely different hydro and atmosphere is convincingly evidenced by many different factors. For example, its relief. There is practically no trace of an early meteorite bombardment on it - the very trace that is clearly visible on Mercury, the Moon and even Mars. There are no such "scars" on Earth. Of course, they once existed, but the active geological life of our planet swept them away. Yes, there are meteorite craters on Venus, but, as already mentioned, they are all extremely young.
It is very likely that they appeared after the planet acquired a dense atmosphere and got rid of the biosphere with the hydrosphere. So it is interesting to study it, if only in order to understand what awaits our planet in the future, when the increased activity of the Sun will turn the Earth into a second Venus. And maybe a way will be invented how to avoid all this?
Also, if life once was, its traces are still there. They are hidden in Venusian sediments under sedimentary rocks, but they must be there and, as the author hopes, await their scientists. Can they be detected now, by our methods? Again, chances are there. According to planetologist A. T. Bazilevsky, for this you need to try to take a soil sample on tesserae, one of the most ancient formations on Venus. Actually, it is there that the Venera-D landing is planned.
Better yet, deliver at least a small fragment to Earth. Even a pinch of such a breed could close many cosmogonic questions. Interestingly, no earth station has yet landed in such an area. For a number of reasons, this happened by chance, because when the stations were created, the relief was presented very approximately.
However, let's hope that in the twenty-first century all questions will be answered.