Reaching Venus: Is it possible to send astronauts to our neighboring planet, and what technologies would be required for such a mission?

Solving the Survival Problem

Venus, with its soft blue glow visible through telescopes, appears to be a paradise from Earth. However, the conditions on the planet are reminiscent of medieval depictions of hell. With temperatures exceeding 400 degrees Celsius year-round, a suffocating atmosphere of carbon dioxide, and a thick layer of yellowish sulfuric acid clouds, the situation is dire. Adding to this is the pressure of 90 atmospheres—comparable to that found a kilometer deep in Earth's oceans—and unrestrained galactic radiation, as Venus lacks an electromagnetic field. The result is a truly terrifying picture. This planet seems designed to demonstrate to humanity that it should not venture beyond the comfort of Earth.

“Today, the entire population of Venus consists of robots. This may not always be the case, but at least in the foreseeable future, it certainly will be. Because with current technologies, we cannot solve the survival problem in such an environment,” notes the expert.

Indeed, humans lack both the spacesuit capable of withstanding 90 Earth atmospheres and a means to transport it there. The hypothetical construction of a permanent station for astronauts on the surface of this toxic planet is too risky:

“The slightest decompression or loss of structural stability will cause even the most powerful station to collapse like an empty tin can. It’s unlikely anyone would want to participate in such a risky project,” believes Ivan Rudo.

One-Way Ticket

But before considering how to survive on such an inhospitable planet, one must first address how to safely return astronauts back.

Indeed, sending a person to Venus did not pose any technical difficulties in the last century. With current rocket engine capabilities, a flight to Venus takes only four months, which is more than twice as fast as a trip to Mars and many times faster than to Jupiter. However, for humans, this would be a one-way ticket—just like the automatic landing vehicles sent there since the 1960s.

The issue is that the power of rocket engines directly depends on the external atmospheric pressure of the planet they are launched from. The greater the pressure inside the engine compared to the outside, the more powerful it becomes. On Earth, this ratio allows for a pressure of 90 Earth atmospheres inside the engine to yield 89 atmospheres, providing enough thrust to overcome Earth's gravity. On Venus, where the pressure is 90 Earth atmospheres, the situation reverses: the flow of burning gases would not escape to propel the rocket off the surface; instead, the engine would act like a gigantic vacuum cleaner, sucking external material into the combustion chamber. Although it is possible to create a much more powerful engine, it would require significantly more fuel, thus greatly reducing payload capacity, raising questions about the feasibility of such a mission.

Theoretically, returning an astronaut from the surface of Venus could be accomplished by leaving the spacecraft in orbit around the planet. One possible method involves using a balloon to lift the astronaut from the surface: essentially, a balloon filled with a lighter gas. Balloons proved effective during the Vega missions in the mid-1980s. The high external pressure on Venus actually works in favor of this approach. The greater the external pressure, the more buoyant force is generated inside the balloon, allowing it to lift heavier loads. Therefore, even a small Venusian balloon could potentially lift a person. The problem, however, is that it would still be impossible to reach orbit with such a device, and a mini-rocket would need to be launched from the upper layers of the Venusian atmosphere to reach the hypothetical spacecraft back to Earth. This is a complex project to bring to fruition.

Settling in the Venusian Clouds

However, if astronauts cannot settle on the surface, they could live—in the clouds, quite literally.

The popular film "Interstellar" depicted a scenario where astronauts managed to live for an extended period in the frozen clouds of an uninhabitable planet. Something similar could be possible on Venus.

The fact is that in the middle layer of Venus's atmosphere, at an altitude of about 40-70 kilometers, both the temperature and pressure are approximately the same as on Earth. If a station were suspended by balloons filled with lighter gas (creating something akin to passenger airships from the early 20th century, but without engines), such a base could drift around the planet at a designated altitude for a considerable time. Moreover, it would drift at a decent speed, as the winds at that height are quite strong.

In this scenario, astronauts would not only study the planet but also see it with their own eyes, theoretically not needing a spacesuit, just an oxygen mask, since Venus's atmosphere is composed entirely of carbon dioxide.

The issue is that we currently do not know how harmful the Venusian clouds of sulfuric acid would be for humans. These clouds form due to the extreme heat on the planet's surface, causing sulfur to evaporate and concentrate in the upper layers of the atmosphere. The thin yellow aerosol of droplets, akin to a wet fog, is undoubtedly harmful to health, but we do not yet know its concentration. In any case, a special suit could easily protect against toxic clouds: materials capable of withstanding the harmful effects of sulfuric acid, such as ordinary plastic, are already known to us.

However, like any other balloon, such a station would only be able to fly for a limited time, and Venusian astronauts would need to be evacuated.

Another less original option would be to send a person to drift in orbit around the planet, creating something like a Venusian ISS. However, in this case, the effectiveness of human presence would be nearly zero: the most a person would see with their own eyes is just the dense layer of Venusian clouds.

Terraforming Venus

Another, much more costly and prolonged approach, which currently seems like science fiction, would be to create Earth-like conditions on Venus.

For humans to inhabit Venus, we must overcome, as we recall, four primary adversaries: the carbon dioxide atmosphere, extreme temperatures and pressure, and radiation.

So, enemy number one: carbon dioxide. Here, the history of our home planet comes to the aid of scientists. Once, Earth's atmosphere was composed of carbon dioxide, but microorganisms that absorbed carbon dioxide and released oxygen helped us. Such microorganisms still exist on Earth and can thrive in the most extreme conditions: in the craters of active volcanoes, in hot geysers where temperatures are comparable to those on Venus. However, making the Venusian air breathable in this way would take many hundreds of years.

One popular idea for "cooling" Venus is to create a massive sail or umbrella that would shade at least a quarter of the planet's surface. Experts believe this would be sufficient to trigger irreversible planetary changes. Hypothetically, radiation could be blocked by creating an artificial electromagnetic field in orbit.

However, the most technologically challenging problem remains—how to get rid of the excessive pressure. And to this day, it is unsolvable.

Will Robots Conquer Venus?

This is just a small part of the challenges humanity faces if it dares to send its representatives to this inhospitable planet. Addressing these issues would require a colossal amount of resources and time. How justified are such expenditures?

“From a scientific perspective, it is much more justified to send robots equipped with the most modern instruments to Venus rather than humans. Yes, we can certainly send an astronaut to orbit Venus. But what will they see from there? Just a thick layer of clouds. In contrast, electronics-laden instruments can see not only in the visible spectrum but also in ultraviolet and infrared, conduct radio scans of the planet's surface, and thus literally see through the clouds. But it’s not just that. When it comes to gathering and accuracy of scientific data, modern electronics will always outperform human sensory perception,” remarks Ivan Rudo.

However, this does not mean that we should stop dreaming about human conquest of Venus.

“The task of sending humans to other planets will always be relevant simply because the instinct of expansion is inherent in humanity. Since ancient times, people have wanted to sail beyond the horizon, to see what lies beyond,” explains the expert. “For example, this instinct drove the settlement of previously uninhabited islands in Polynesia and the American continent: the more territory you as a biological species occupy, the more resources you obtain for the survival of your kind. Looking at it more broadly, this is not just one of the oldest mechanisms of the human brain. It is something that is inherent even in the most primitive forms of life: bacteria and viruses. Even if such expansion seems pointless, it is very important for human self-esteem as a species. To achieve this goal, we have a rich arsenal of existing and promising smart technologies.”

This material was prepared with the support of the Ministry of Education and Science of Russia.