Life on Venus and the U-turn of Roscosmos: Does Phosphine Really Speak About the Population of the Nearby Planet and Why Russia Decided to Sharply Activate its Venusian Plans?

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Life on Venus and the U-turn of Roscosmos: Does Phosphine Really Speak About the Population of the Nearby Planet and Why Russia Decided to Sharply Activate its Venusian Plans?
Life on Venus and the U-turn of Roscosmos: Does Phosphine Really Speak About the Population of the Nearby Planet and Why Russia Decided to Sharply Activate its Venusian Plans?
Anonim

The recent discovery of the biomarker phosphine in the atmosphere of Venus has given rise to a lot of controversy - is there life there? Not everything is clear with this yet. But it is definitely clear that Roscosmos is learning to use HYIP for PR purposes: the state corporation has already offered to take a sample of the substance of this planet. To do this, she will abandon the joint project with NASA "Venus-D" ("D" means "Long-lived") and replace it with "hers." But is there any reason for such a rush? What is phosphine actually talking about in the clouds of the second planet? And, most importantly, will Russia cope with sampling from there? Let's try to figure it out.

Balloons on Venus

What did they find

According to a scientific work published in Nature Astronomy, phosphine, a gas with the formula PH3, was discovered on Venus at altitudes of 50-60 km. Its concentration was small, only 20 parts per billion, slightly higher than methane on Mars, but it is very difficult to dispute the very fact of registration.

The media - this time very correctly - wrote that this is a very likely sign of life. It is worth figuring out why. First, phosphine is highly reactive. As a result, it decomposes at elevated temperatures into pure phosphorus and hydrogen, of which it is composed. Secondly, after that, phosphorus, under the conditions of Venusian clouds, should elementarily fall down, where, we note, there is no hydrogen - that is, from the places where it was noticed by terrestrial telescopes, phosphine should constantly disappear. Thirdly, and most importantly, on Earth this gas before the appearance of people was formed in only one way - as a result of the activity of anaerobic bacteria.

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Unfortunately, this gas is so rare even on Earth that it is difficult to find out which bacteria produce it. However, the fact that in our country it is mainly biogenic is a fact, since it appears literally at every landfill or at any large pile of manure. Both there and there anaerobic microbes (bacteria and, to a lesser extent, archaea) multiply rapidly, but no inorganic processes capable of generating such a compound go there.

Is it possible in principle to produce phosphine in a non-biogenic way? Yes, of course: for example, there are traces of it in the atmosphere of Jupiter. But calculations show that to obtain it without the participation of living beings, with their complex catalytic processes, a huge amount of energy is needed.

In the case of Jupiter, it is clear where it can come from: phosphine rises there from the bowels of the planet, where temperatures are measured in thousands of degrees, which allows phosphorus to react with hydrogen, which is very common in gas giants. As a result, it is phosphine that is inevitably formed. But Venus is much cooler than in Jupiter's interior, and most importantly, there is almost no free hydrogen in its atmosphere.

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Purely theoretically, phosphine on Venus can be emitted by volcanoes (although this does not occur on Earth on a noticeable scale). However, the authors of the work in Nature Astronomy correctly note that the required scale of eruptions should be hundreds of times higher than the Earth's. And this is if we proceed from the most optimistic assessments of the survivability of phosphine in the atmosphere of the second planet.But Venus has no traces of current volcanic activity hundreds of times higher than Earth's. In addition, in the lower layers of its atmosphere, phosphine, due to the high temperature, must decay within an hour, that is, almost immediately after the eruptions.

Because of all this, back in 2019, researchers from the Massachusetts Institute of Technology (USA), in their work in the journal Astrobiology, suggested looking for phosphine on terrestrial exoplanets as a sign of the presence of life there. It was in her footsteps that the analysis of the spectra of the Venusian atmosphere was organized - and this gas was found there.

But what about the "hellish conditions on Venus", where "there can be nothing alive"?

The reader has the right to doubt. The school says that on Venus +462 ° C Celsius, that is, warmer than the melting point of lead. And the pressure is 93 times higher than on the surface of the Earth - if you put a pine cube there, it will be compressed twice, on Earth the same pressure is 930 meters under water. What kind of life can exist in such conditions?

However, there is no paradox here. The fact is that at an altitude of 50-60 kilometers Venus, as Soviet probes established half a century ago, has approximately terrestrial temperature conditions: for example, at 55 kilometers there is invariably 21 degrees Celsius. Day and night, winter and summer - good because of the density of the Venusian atmosphere, there are simply no seasonal and daily temperature fluctuations there. The pressure at 55 kilometers is equal to half the earth's pressure at sea level - or the same as ours at 5.5 kilometers. This is quite acceptable for terrestrial microbes, and even some climbers, after a long adaptation, are quite capable of operating under this pressure.

It is because of roughly terrestrial temperatures and pressure that the clouds of Venus have long been suggested as a possible zone of colonization. The fact is that, from the point of view of the health of the colonists, the presence of decent gravity on them is considered the main resource of other planets. Otherwise, you need either centrifuges for increased gravity during sleep, or humility before the processes of degradation of bone and muscle tissue of people living there. The Venusian level of gravity is 90.4% of the Earth's, and in this regard, we will not find the best object for colonization in this system.

At the same time, unlike Mars, at an altitude of 55 kilometers, colonists will not need either heating or cooling: it will be enough to maintain balloons with their “aeronautical” cities at the same altitude. The level of solar illumination at 55 kilometers is even slightly higher than that of the earth, that is, in transparent galleries on the "back" of giant airships, it will be quite possible to grow terrestrial plants. At an altitude of 100 kilometers, there is an ozone layer, although much thinner than the earth.

Of course, at 55 kilometers, the level of ultraviolet radiation is higher than "our" norm, but ordinary glass easily blocks it to values ​​below the earth. Although the second planet does not have a serious magnetic field, the level of cosmic radiation there is quite low: after all, the atmosphere, like on Earth, effectively absorbs cosmic rays. In general, as Jeffrey Landis of NASA notes: "The atmosphere of Venus is the most Earth-like environment in the solar system (after Earth)."

By the way, when we say "balloon", this does not mean at all that such colonization would require special light gases that are used to fill balloons on Earth. In fact, this does not even require a balloon in the usual sense of the word.

The fact is that ordinary earthly air is much lighter than Venusian - almost pure carbon dioxide. Therefore, a simple containment, filled with banal air, will float in the atmosphere of Venus. And in the presence of a compact atomic reactor and / or plants in transparent galleries, the colonists will always be able to get oxygen from the carbon dioxide gas envelope of the second planet surrounding the colony-balloon.

NASA workers state that a kilometer-long spherical containment on Venus will have a lifting force of 0.7 million tons - quite enough to support a large settlement.The two-kilometer balloon will already lift about six million tons.

The last objection remains: the Venusian clouds contain droplets of sulfuric acid. Will it corrode the structure of such a colony? This question was answered long ago by Soviet engineers. Back in 1985, the balloons they created quite successfully explored the cloud layer of Venus, and at the same time their shell was made of a thin layer of ordinary Teflon.

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Then, for the first time in the history of earthlings, two balloons were able to explore another celestial body for a couple of days in a row, having traveled eleven thousand kilometers above it, before they descended (following the plan) to the surface of the planet. In the process, they noticeably clarified our ideas about the cloud layer of the planet, and also discovered the presence of strong thunderstorms on Venus.

By the way, today - after 45 years - humanity has not been able to repeat the Soviet achievement. Not once since the 1980s has it been possible to explore another planet with a balloon, airplane or helicopter type aircraft. Only in the coming years will a miniature drone of the American rover be able to begin experimental three-minute flights on Mars.

In fact, the Soviet missions showed that any person in a Teflon suit with an oxygen apparatus can walk on the surface of a balloon colony without any space suit - but on Mars and the Moon, as we already wrote, the need for such spacesuits is very great and difficult. problem being solved.

Where does life come from?

So, in principle, phosphine on the second planet can really be a product of the vital activity of anaerobic bacteria - at least, science today does not know non-biogenic processes that could form it there. But another question arises: where do such microorganisms come from on Venus?

Of course, it would be tempting to assume that the earthlings themselves brought them. A number of Soviet descent vehicles - and the same balloons - were disinfected, which, as is known today, is insufficient to kill the most tenacious terrestrial bacteria and archaea. But this is rather doubtful: many anaerobic microbes do not tolerate oxygen-saturated air poorly, therefore their presence in the assembly shops of NPO im. Lavochkin”in the Soviet era seems unlikely.

There is a much simpler explanation. In 2016, it became clear that at an early stage in the history of the solar system, Venus could be significantly more suitable for the emergence of life than Earth. After all, a day on the second planet of our system is 243 times longer than the current terrestrial ones - and this is an extremely powerful cooling factor of the planetary climate.

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The long night means that much more than on Earth, some of the heat received from the sun's rays will be re-emitted into space in the form of infrared radiation. That is, although Venus receives almost one and a half times more solar energy than our planet, but with the terrestrial composition of the atmosphere, it would have an average temperature equal to ours.

Moreover, 0, 7-2, 9 billion years ago, this temperature should have been even slightly lower than on today's Earth - about the same as ours 15 thousand years ago, that is, about plus 11 Celsius. According to the calculations of American and Swedish researchers, at that time, oceans and seas covered up to 60% of the surface of the second planet, and the atmosphere was mainly nitrogen - as on the early Earth. According to some researchers, it cannot be ruled out that it was on Venus that life arose for the first time in the solar system.

But how could she survive there?

As you know, in the last hundreds of millions of years, giant eruptions began on Venus, which emitted huge amounts of carbon dioxide into the atmosphere. He raised the temperature above plus 450 Celsius, as a result of which the planet's oceans and seas have long been lost, and its surface is no longer suitable for terrestrial life. It turns out that even if this planet was the ancestral home of life in our system, now it should become dead.Even relatively favorable conditions in the cloud layer will not help: after all, life cannot hover in the clouds for hundreds of millions of years in a row. Or can it still be?

A group led by Sara Seager, one of the authors of a recent work on Venus phosphine, tried to answer this question in another publication. Together with her co-authors, she turned to the results of a study of the tropo- and stratosphere of the Earth and found out that there are microbes there up to an altitude of tens of kilometers, and up to the upper part of the troposphere - where the temperature and pressure are much lower than in the Venusian clouds - they retain metabolic activity. They did not find traces of division there, but one must understand that it is extremely difficult to study unicellular organisms under such conditions, therefore such division (reproduction) cannot be ruled out in any way.

But the problem is that the clouds of Venus are composed mostly of sulfuric acid (no less than 85%). There is also water vapor there, but at a concentration of 40-200 ppm, which is extremely small. Say, on Earth, the driest air is in the Atacama - but even there the relative humidity is 2%, and in the clouds of Venus - 0.07%. Under such conditions, water, in principle, can still be concentrated in quantities formally sufficient for survival - in drops of sulfuric acid, making up an impurity that does not exceed 15%. In addition, in these drops, water molecules are, as it were, "attached" to sulfuric acid molecules, and therefore their use for any potential local life is difficult.

And nevertheless, it is impossible to deny the possibility of the existence of life even in such conditions. Firstly, hydrogen sulfide and sulfur dioxide were found in the clouds of Venus long ago, which react with each other. And therefore, strictly speaking, they cannot exist without external replenishment due to some unusual chemical reactions. Carbonyl sulfide (O = C = S) was also found there.

On Earth, this compound is a clear biomarker, by changing traces in the atmosphere, polar ice core researchers can accurately determine how biomass on our planet changes over time. In addition, it is very difficult to obtain carbonyl sulfide in a non-biogenic way, and before the advent of industry, it was produced on the planet exclusively by living organisms, due to their extremely effective catalysts.

Finally, Seager et al. Notes, the UV images show that there are some strange formations in the clouds of Venus that absorb ultraviolet light - the main part of it that reaches this layer of the atmosphere. The sizes of these particles vary in the micrometer range (on our planet, bacterial spores often have such sizes) to even larger ones. This, coupled with the presence on Earth of photosynthetic anaerobic microorganisms that use sulfur instead of carbon, in principle, allows us to expect that there are some possibilities for photosynthesis in the Venusian clouds.

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Relatively high ultraviolet light cannot prevent it - on the contrary, there are living organisms on Earth (fungi Cryptococcus neoformans) that use ionizing short-wave radiation as an energy source. Moreover, Seager notes, on our planet, such radiation lovers are found both in nature (Antarctic mountains) and in a technogenic environment (components of cooling systems for nuclear reactors, ISS). That is, for many living organisms, ultraviolet light is not a problem, but a source of useful energy.

From all this, her group concludes: on Venus, life in the clouds is possible, but life is unusual, more reminiscent of terrestrial "sulfuric" photosynthesis without access to oxygen than anything else. The life cycle of such photosynthetic microbes is simple: in the cloud layer, due to the hydrophilic shell, they become the center of the formation of droplets of sulfuric acid and water. Then they begin to photosynthesize using the sulfur dioxide (SO2) and water around them. From their molecules, they produce H2SO4 that very sulfuric acid, of which, in fact, local clouds mainly consist.

Phosphorus, like, for example, iron, is an inevitable participant in the life cycle of a wide variety of organisms, therefore, in the course of a number of reactions, it can, in trace amounts, be released in the form of phosphine, which researchers found with the help of telescopes.

By the way, we mentioned iron for a reason: Soviet devices, including balloons, found traces of chlorine at the bottom of the cloud layer. Meanwhile, as Seger notes, iron chloride is lifting from the planet's surface with updrafts. If local microbes use this iron, they must inevitably release some amount of free chlorine into the environment.

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Seeger et al. Give an example of a creature close to possible Venusian life - the photosynthetic prokaryote Prochlorococcus. It is a very small organism, 0.5-0.7 micrometers in diameter, in which, due to the environment poor in phosphorus, the outer wall consists of sulfur and sugar compounds. 99% of the lipids in the cell membrane of this organism include sulfate groups instead of phosphate groups - and a similar adaptation would make sense on Venus, with its phosphorus deficiency and excess sulfur.

Drops, which contain such photosynthetic organisms that produce sulfuric acid, grow in size over time (due to the surrounding sulfuric acid vapors and water) and begin to descend. In this case, local organisms must enter the spore production phase and then die. Ascending currents will inevitably raise some of the droplets to a height where some of the spores can give rise to a new life cycle in the Venusian clouds.

Of course, such an environment will be very difficult to survive. There are no places on Earth where bacteria or archaea could live in sulfuric acid slightly diluted with water. Therefore, we do not know for certain whether they are able to protect themselves from the effects of acids in such conditions. But it is also impossible to exclude this scenario in advance.

Is the response of Roscosmos adequate? Is the Venusian mirage worth breaking with NASA?

So, we have established that life on Venus is, in principle, possible. But with some aspects of the activity of intelligent life on Earth, questions still remain.

On September 15, 2020, a message appeared on the Roscosmos website responding to the discovery of phosphine and stating:

“… A decision was made to implement the previously planned Venera-D mission, which includes landing and orbital modules, as an independent national project without widespread involvement of international cooperation. In the framework of comprehensive studies of the planet, among other things, samples of its soil and atmosphere will be studied, as well as the nature of the evolutionary processes of Venus, which allegedly suffered a climatic catastrophe associated with the greenhouse effect, which is so much talked about today in relation to the Earth."

What is it? It is well known that the Roscosmos budget is half a dozen times less than that of NASA. So what is the point of refusing to cooperate with the Agency, previously envisaged as part of the Venera-D program? However, a closer look at the question of the reasons for refusing to cooperate becomes much easier to understand.

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As noted by N + 1, whose editor spoke with members of the RAS Council on Space, back in July 2020, Roskosmos proposed to radically revise the Venera-D mission. According to the revised version, already at the end of the 2020s, a landing station with a number of balloons could fly to the planet, and this station was supposed to take a soil sample from the planet's surface - and then deliver it to Earth.

It is easy to see that such a project could not have been implemented in international cooperation anyway: NASA would never have done it. To begin with, the collection of soil requires its delivery to Earth, which is difficult to do from the surface of Venus. Therefore, the proposal of Roskosmos provided for the rise of a soil sample in a balloon into the upper atmosphere. From there, a rocket lifted by a balloon was supposed to take the sample into space, where it would head towards Earth.

These are tasks of extremely high complexity and, frankly, requiring a huge mass of the lander. We are talking about many tons: as we have already mentioned, the gravity on Venus is 90% of the Earth's, and the return of soil from there, for this reason, even with a balloon, will be extremely energy-consuming. Naturally, NASA would not undertake such a risky project - this is not the style of the Agency.

The question arises: why does Roscosmos need this? Since those Soviet missions to Venus, Russia has not had successful interplanetary missions, even with moderately difficult tasks. The last attempt at such a mission was drowned in the Pacific Ocean ("Phobos-ground"). Trying to jump from zero missions directly to a mission of such a huge scale and complexity looks extremely specific - simply put, like a gamble with unworked means of execution. It is not surprising that the members of the RAS Space Council spoke out against it.

It is difficult to clearly understand the motives of the Roskosmos leadership in this case. There are two most likely versions: either it does not expect to sit in its chairs until the end of the 2020s and be responsible for the risks of such a project; or he wants so much impressive and successful pictures for the public that he is ready even for such, in the language of the Russian Academy of Sciences, "semi-fantastic" projects, just to create a favorable impression on the masses of their activities.

If one of the listed cases is true, then you can understand the leadership of Roscosmos. It is fairly obvious to all observers of the space industry that in the 2020s SpaceX will debug its super-heavy and largest space carrier in the history of mankind, Starship. After that, the United States will inevitably go to the moon, and in a few years - to Mars. Years of stubborn disregard by Roscosmos of Musk's projects (in the form of unwillingness to create competing carriers for a flight to Mars) preclude sending expeditions there in the foreseeable future for our country.

Against this background, it is urgent to announce some high-profile project, and the degree of its feasibility in the foreseeable future may not be particularly important. After all, it is clear that after the start of Starship flights, the entire Russian space program will have to be revised anyway, Angara will instantly become deeply obsolete, and our country will have to redo all notable space projects in general. Against the background of all this, hardly anyone will ask for the unfulfilled project of delivering soil from Venus.

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