Venus, often called Earth´s sister planet, is a terrestrial planet, slightly smaller than our own world. With a distance to Earth between 38 million to 223 million kilometers, the rocky world is closer to us than Mars, which has a distance to Earth between 140 million to 225 million kilometers. However most people think humanity will colonize Mars before Venus. But why is this the case, what makes Venus so difficult to colonize and how would it potentially be possible.
One big issue of Venus is its runaway greenhouse effect, which caused the planet to heat up to 462°C. With an atmospheric pressure of 92 bars, Venus has the densest atmosphere of all four rocky planets of our solar system. This atmosphere is mostly comprised of CO2, which makes up more than 96% of the venusian atmosphere. Additionally, the venusian clouds, which cover the whole planet, are made of highly corrosive sulfuric acid. But more about the challenges of living there in the next blog post. In this article we will only focus on the technical way of colonizing the planet. We will take a look on floating city’s and how to completely terraform the hot planet.
To avoid the extreme conditions on the venusian surface, concepts of floating citys have been proposed. These citys would be stationed about 50 kilometers above the surface, where the air pressure would be around 1 bar and the temperatures would not be that extreme. Therefore, the habitats would be equiped with a huge ballon filled with a gas leighter than the surrounding atmosphere. Because the atmosphere of Venus is mostly made of relatively heavy CO2, different gases such as hydrogen, helium, nitrogen or even oxygen could be used as floating gases. The habitats would then be placed under the envelope.
On theses stations it would even be possible to go outside, only wearing an acid resistence suit against the sulfuric acid clouds. These settlements in the venusian clouds could either be occupied for a certain period of time to allow scientists to study the planet, or serve as a permanent outpost of humanity, until Venus is terraformed.
One big issue is the extreme heat of over 400°C. At this temperature, machines and especially humans are not able to survive for a very long period of time. To get rid of the heat, it would be possible, to place a big mirror or shade between Venus and the Sun, to block all electromagnetic rays originating from the star. Over time, Venus would lose heat and start to get colder. However, this process, takes a long period of time.
At one point, the temperature would have fallen low enough, so the CO2 in the venusian atmosphere would start to fall down to the surface as rain, forming lakes and oceans made of liquid carbon dioxide. If the temperature would fall even lower, the remaining CO2 would start to freeze and fall to the ground as snow, covering the planet’s surface. Due to the disappearing of the CO2 in the atmosphere, the air pressure of 92 bars would also fall drastically. After all carbon dioxide has fallen down to the ground and frozen there, humans could start covering the dry ice and use the land for building.
To get rid of the sulfuric acid, it could be turned into sulfur, hydrogen and oxygen. The oxygen of the sulfuric acid, as well as the oxygen in the carbon dioxide could be used to ad a breathable atmosphere to the planet. To form water, the hydrogen gained from the sulfuric acid will not be enough. Therefore, either hydrogen would be tranported to Venus from Jupiter, or asteroids and moons are farmed for water ice, which would than be transported to Venus.
To be protected against the cosmic and solar rays, a magnetic dipole, stationed between the Sun and Venus at the L1 Lagrange Point, could be used to generate an articial magnetosphere.
The last big milestone in terraforming Venus would be to alter the day-night cycle. This could be solved by spinning up the planets rotation, using flybys of big asteroids and comets. However this would take a very long time and would be extremely inefficient. Another solution would be to export the atmopshere into space using a electromagnetic catapult, called a mass driver. Instead of spinning up the planet, mirrors could be placed in orbit around Venus, which could create an articial 24 hours long day.
There are many problems, which need to be solved before humanity can colonize the hot planet. Before flying to Venus we should first “practice” on our Moon and on Mars. After we have gained the knowledge, we can think about futher expansion into the solar system.