Terraforming Mars: There’s not enough carbon dioxide

The atmosphere of the red planet not only lacks enough oxygen, it is also very thin. Instead of a surface pressure of one bar on Earth, the surface pressure in Mars’s atmosphere reaches only 6 millibars, thus, less than one-hundredth of the Earth’s surface pressure. Consequently, to work on Mars, astronauts would have to wear pressurized suits. The atmosphere would have to be considerably denser for a respiratory mask to be sufficient. If the density were even higher, carbon dioxide, the main...