What is the reason behind our inability to breathe on Mars ?

Although the colonization of Mars is expected to occur in the near future, scientists are currently working to overcome numerous challenges in order to establish a habitable outpost on its surface. These obstacles include intense winds and extreme cold, lethal radiation, and, most importantly, an atmosphere that is incompatible with human respiration.

In the latest announcement, NASA has revealed its intention to send the initial human mission to Mars by 2040. Following this milestone, a colonization project is set to commence after conducting a preliminary rehearsal on the Moon. Despite the promising prospects, it's crucial not to overlook the inhospitable nature of Mars. Although it may have potentially sustained life millions of years ago, it is currently an unsuitable environment for human habitation.

So if you ask yourself the question : can we breathe on Mars ? The answer is no. In an article dedicated to this subject on the site The Conversation, Phylindia Gant and Amy Williams, two experts in planetary sciences, dwell on the subject and explain to us why.

First of all, they remind us that on Earth, the air we breathe is made up of several gases. It contains mainly nitrogen (78%) and oxygen (21%) which is more generally called oxygen. The remaining 1% represents a multitude of other gases in minute quantities such as carbon dioxide responsible for global warming, helium or argon to name a few. “When we inhale, our body does the sorting on its own. It extracts the oxygen it needs and expels the rest” detail the scientists.

Death in a split second

The reason we couldn't breathe on Mars lies in the composition of Martian air. Phylindia Gant and Amy Williams specify: “the atmosphere on Mars represents only 1% of the volume of the Earth's atmosphere. In other words, there is 99% less air on Mars than on Earth”. This is due to the size of the red planet which is half that of its blue neighbour. There, the gravity is not strong enough to hold the gases evaporating into space.

In this small volume of air, we mainly find carbon dioxide, at 96%. According to the National Institute for Research and Security (INRS) CO2 is deadly from a concentration of 11%, so imagine what a single puff of Martian air would give. Suffocation and death would be immediate.

In fact, it could not really happen because it is another parameter that will kill you before you even think of breathing. Remember this rule of physics : the lower the atmospheric pressure, the lower the boiling point of a liquid. On Mars, this pressure is almost non-existent. One exit out of a pressurized shelter and your blood would boil instantly. If you've seen the movie Total Recall, the fate of characters kicked off base is anything but desirable.

Terraform Mars

But then why is the Martian air almost entirely composed of CO2 ? Why is there no oxygen ? On Earth, the vast majority of the oxygen available to us comes from the oceans and micro-organisms that carry out photosynthesis. The rest comes from forests. Without water and without vegetation on Mars, it is impossible to generate breathable air and to generate an atmosphere. The only solution to consider a real colonization of the red planet would be to engage in terraforming. This would involve evaporating the ice present on the poles to form primitive clouds, extracting and releasing the oxygen present in the nitrates and minerals contained in the ground.

Phylindia Gant and Amy Williams are also attached to the Perseverance rover mission which surveys the Martian surface in search of traces of life. In their article, they mention a little-known tool that equips the machine, the MOXIE. This small device works on the principle of electrolysis which separates the elements present in the CO2. Carbon and oxygen. Currently, MOXIE sucks in Martian air and releases as much oxygen as a tree. On its site, NASA specifies that it is a prototype which will eventually be used to install a giant MOXIE when the first astronauts are on site. Its production will not be used to make the air breathable but will allow future rockets to take off again because fuels need oxygen to burn. A return ticket of sorts.