Many scientists believe it would be possible to maintain a permanent human presence on Mars or the Moon. On the other hand, conditions on Venus are so extreme and inhospitable that maintaining a human presence there would be impossible.

First, atmospheric pressure at Venus’ surface is at least 90 times greater than the pressure at Earth’s surface. This means that a force of 100 kilograms is pressing down on every square centimeter of surface. All spacecraft that have landed on Venus have been crushed by this extreme pressure within an hour of landing. Almost anything humans might land on Venus would be crushed as well.

Second, as far as we know, there are no reservoirs of water on Venus’ surface, and the planet’s atmosphere, made up mostly of carbon dioxide, nitrogen, and sulfuric acid, contains hardly any oxygen or water vapor. Water and oxygen would therefore probably have to be supplied to Venus from Earth. The idea of ensuring a regular supply of water and oxygen from Earth is impractical in the extreme and would probably defeat the purpose of establishing a permanent station on Venus.

Third, very little sunlight reaches the planet’s surface. About 60 percent of the sunlight that hits Venus is reflected back into space by the thick clouds that fill the atmosphere, which means that only 40 percent of the sunlight can get through the clouds. Below these clouds is a dense layer of carbon dioxide, which blocks even more light, so very little light reaches the surface. The lack of light would prevent the use of solar power cells, so humans could not get electricity to power their machines and equipment.