Thin atmosphere of Mars
Mars has less surface gravity than Earth. The force is just powerful enough to retain most gases, but it cannot prevent water vapour from evaporating into space. As a result, the water vapour concentration in the atmosphere of Mars is 30 times less than in the atmosphere of Earth. This explains the thin nature of the atmosphere of the red planet.
The composition of Mars’ atmosphere (gases):
- Carbon dioxide (CO2)
- Nitrogen (N2)
- Argon (Ar)
- Oxygen (O2)
- Water (H2O)
- Carbon monoxide
No ozone layer on Mars
The quantities of ozone and water vapour are so small that, unlike the ozone layer on Earth, there is no protective layer on Mars that blocks out ultraviolet rays. The ultraviolet radiation reaches the soil unhindered and can destroy any organic molecules. For some, this fact is enough to argue that life on Mars is impossible.
Others, however, point out that there are ecological niches beneath the surface that may once have favoured the development of bacteriological colonies. These colonies may still persist to this very day. This possibility is a hot topic for discussion that will last for some time without other, more solid, evidence.