Mars is the closest planet to Earth, and the best candidate for the construction of a human colony beyond the Earth. Billions of years ago, Mars’ atmosphere was dense enough to let liquid water flow through its surface.
However, its atmosphere has degraded through time, causing the disappearance of water on its surface. Nowadays, the atmosphere of Mars is 100 times less dense than the one of the Earth.
Mars’ atmosphere is so thin, that it could be considered as empty space. Consequently, a person without a spacesuit would not be able to walk through the Martian surface without dying in the attempt. But, apart from this danger, the atmosphere of the red planet is also unbreathable for humans.
The terrestrial atmosphere is formed by 78% nitrogen, 21% oxygen, and other small percentages of other elements (0.04% of carbon dioxide…).
In contrast, on Mars, the content of carbon dioxide in the atmosphere is 95%. The two other most common gases in its atmosphere are nitrogen and argon, with 2.7% and 1.6% respectively.
Apart from the mentioned gases, we can also find small quantities of oxygen (forming 0.13% of the atmosphere) and carbon monoxide (0.008%). There are also tiny quantities of water vapour, neon, nitric oxide, xenon, ozone and methane.
Potential use for humans
The atmosphere is a resource of which we know the composition, and which is available in any landing site. The first human colonies on Mars could take advantage of the atmosphere for diverse purposes:
- One of the possible uses of Mars’ atmosphere could be the manufacturing of fuel for rockets from the carbon dioxide (CO2), as proposed, between others, Robert Zubrin, with its plan for the colonization of Mars named “Mars Direct”. This could be done by means of the Sabatier reaction, which converts carbon dioxide, along with additional hydrogen, to produce methane (CH4) and oxygen, which are a very good combination for rocket fuel.
- Moreover, small quantities of other gases could be extracted from the atmosphere, to supply diverse construction processes. Another option is to extract the nitrogen present in the atmosphere to create a breathable atmosphere, similar to the one of the Earth, inside the Martian colony.
Evolution of the Martian atmosphere
As I have explained before, billions of years ago, the atmosphere of Mars was much denser than it is today, allowing the presence of liquid water, and of enormous oceans, on its surface.
However, for some reason, the Martian atmosphere lost its content to space. The following are three possible causes that could explain this phenomenon:
- The gradual erosion of Mars’ atmosphere due to the solar wind. As it has been demonstrated, the erosion of the atmosphere increments during solar storms. In addition, the lack of a magnetic field on Mars doesn’t offer any protection against this problem.
- Another possible cause for the loss of atmosphere is the catastrophic collision of a sufficiently large body to make a significant percentage of Mars’ atmosphere disappear.
- It is also thought that the interaction of the solar wind with the electromagnetic fields of the planet, a long time ago, could have caused the loss of the atmosphere.