Everyone who is in one way or another connected with space is making a lot of efforts, both mental and physical, to colonize Mars. But if humanity really plans to become a multi-planetary species, colonization of other planets is not far off. For example, Venus. More precisely, its clouds. This planet is hot enough to melt lead. Acid rain is dripping from the skies and can char your flesh to the bone in the blink of an eye. And yes, this is a great place to stay. It is Venus, not Mars, that may become the favorite place of residence for space travelers of the future.
For all Elon Musk's enthusiasm, any colony that chooses Mars as their new home will face major challenges. The thinnest atmosphere on the planet's surface offers no breathing space or protection from dangerous solar radiation.
Venus has its own problems: it is impossible to live on it. In principle, life cannot exist there.
At first glance, this planet is remarkably similar to the Earth: gravity is 90% of the Earth's, and it is 30% closer to the Sun than we are. But a closer look reveals a terrible difference. If Mars has almost no atmosphere, Venus has too much of it. It is 90 times denser than Earth, composed mostly of carbon dioxide (CO2) and shrouded in clouds of pure sulfuric acid.
The greenhouse effect of Venus's atmosphere traps an enormous amount of solar heat, making Venus's surface successfully the hottest place in the solar system outside of the sun itself. At a surface temperature of 450 degrees, this is enough to melt zinc, lead and most organic materials. And together with atmospheric pressure equivalent to a kilometer deep in the ocean, even a nuclear submarine will be crushed.
The pressure is so great that carbon dioxide itself is pressed into the surface and takes on the exotic state of "supercritical fluid", which is neither gas nor liquid, but has the properties of both. On Earth, supercritical CO2 is a dangerous and exotic substance that is used as an industrial solvent and sterilizer - and on the surface of Venus there is literally an ocean of this substance.
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The USSR sent several probes to Venus in the 60s, 70s and 80s of the last century; unsurprisingly, most of them failed to reach the surface, most of them crashed. The most successful probe was Venera-13, it managed to hold out for more than two hours before it also succumbed to strong pressure and heat. The pictures he sent showed a world that was unfriendly, withered and completely alien to us.
What hope can we have for living there? In short: avoid the surface.
"The problem with Venus is that the surface is too far from the pressure level of one Earth's atmosphere," says Jeffrey Landis, a NASA scientist and science fiction writer who was one of the first to propose the idea of populating Venus's clouds. "The atmosphere of Venus is the most terrestrial environment in the solar system (not counting the Earth)." 50 kilometers above the surface, Venus turns out to be extremely friendly.
First, the air pressure becomes normal as it approaches one atmosphere. At the same time, the atmosphere is sufficient to provide protection from radiation comparable to the shield that we receive from the atmosphere on Earth. The temperature, oddly enough, is also approaching comfortable - about 60 degrees Celsius. It's hot, yes, but our technology allows us to cope with it. And if you go up another couple of kilometers, the temperature will drop to 30 degrees, while the atmosphere will not lose its protection from radiation. And since the gravity of Venus is almost the same as that of the Earth, colonists living there for years will not have fragile bones and weak muscles.
The problem remains: how to stay afloat in a stifling atmosphere. But the solution is surprisingly simple. CO2 is heavier than air on Earth - A balloon on Venus filled with a terrestrial mixture of nitrogen and oxygen will be lighter than Venus's air. Fill a Venusian balloon with terrestrial air and it will fly across the sky like a helium balloon.
It turns out that to live on Venus, you just need to fill the balloon with nitrogen and oxygen, and live inside the balloon. A large enough ball will have enough lift to support you and your supplies - and a very large ball can do even more. “A spherical ball with a diameter of 1 km can lift 700,000 tons. A balloon 2 km in diameter will lift six million tons,”says Landis. "The result is an environment in size like a typical city."
But what if the balloon bursts? It won't look like a regular burst balloon. Since the pressure inside the ball will be the same as the pressure outside, air will seep through the crack slowly and will not lead to an instant catastrophic explosion. It will look like an open window. The larger the living environment, the slower this process will be.
It is even easier to protect the balloon from the sulfuric acid clouds. This solution has been tested by our compatriots - and you have the honor to use it in the kitchen. In 1985, the Soviet mission "Vega" orbited Venus on its way to Halley's comet. Vega brought two balloons into the atmosphere of Venus, which floated in the atmosphere exactly at the level that we are talking about for two days. The outer layer of these balls was plain Teflon. Teflon provides absolute protection against sulfuric acid.
Problems remain that any colony will sooner or later face, such as finding the raw materials needed to survive and creating a complex biosphere capable of sustaining human existence for a long time. With the atmosphere of Venus, this will be difficult, but possible. CO2 will have to be split into oxygen and carbon; sulfuric acid can be split into water, oxygen and sulfur.
And while the surface of Venus will remain inaccessible to humans, robots could explore and develop solid ground. They could be controlled by residents of a cloud city in real time - it is impossible to do this from Earth, since the signal will last for 20 minutes.
And yet, do not rush to pack your bags - we know too little about Venus to say for sure that we can build a cloud city. “The first thing we'll have to do is send out a couple of space probes just to learn more about Venus,” Landis says. "Venus is one of the least studied planets in the solar system."
We don't know much about Venus because most of our exploration of Venus took place early in the space race. Our technology has improved and we have turned our attention to other planets, especially Mars. “We learned a lot about Mars: about its early history, about the atmosphere, about the climate,” says Lori Glaze of NASA. "Venus sagged slightly."
But Glaze is working to fix it: he is now leading DaVinci, a mission that suggests sending a robotic probe into the depths of the Venusian atmosphere to better understand our neighbor. DaVinci will try to answer fundamental questions about Venus, about the composition and dynamics of its atmosphere.
Venus is an amazing planet with many mysteries. Perhaps we should go back to studying it.
ILYA KHEL