Humans have long had the vision of colonizing foreign planets. Science fiction films and novels present future scenarios in which humans travel the universe and inhabit foreign planets.
Mars is most similar to Earth among the planets in our solar system. Nevertheless, its conditions are not suitable for human life.
Mars is very cold and the atmosphere is largely carbon dioxide. Just a moment: A lot of carbon dioxide and still low temperatures? Where’s the greenhouse effect?
The greenhouse effect on mars?
The greenhouse effect makes life possible for humans in the first place. The global mean of near-surface air temperature on our planet through CO2, water vapor and other greenhouse gases is 15°C instead of -18C °.
But what is it like on Mars? Is there a greenhouse effect there too?
In short, the answer is yes, but the effect is very small compared to Earth. The reason: Mars is smaller and lighter than our home planet. The lower gravity binds less gas to the red planet, making its atmosphere lighter and thinner than Earth.
The pressure of the atmosphere on the surface of Mars is only 0.6% of the atmospheric pressure on the surface of the earth. The greenhouse effect remains small, despite a CO2 share of approx. 96%.
Why doesn’t CO2 work on Mars as it does on Earth?
The large mass and the high air pressure of our atmosphere forces the gas molecules closer together. It thus facilitates the retention and storage of thermal energy. In contrast, under the lower air pressure on the red planet, the molecules are further apart and thermal energy escapes back into the universe more easily.
The relative composition of the Martian atmosphere therefore plays a subordinate role for the greenhouse effect. It only causes the average temperature on Mars to rise by around 5°C, while on Earth it increases by around 33°C.
Future settlers would have a hard time on Mars without the greenhouse effect. There are various approaches to making our neighboring planet habitable through terraforming.
For example, releasing the CO2 bound in the surface of Mars into the atmosphere and thus heating it up. According to a study supported by NASA, Mars does not have enough CO2 for this plan. Turning the desert planet into a garden of Eden remains an idea for science fiction novels for the time being.