What conditions on Mars could make life possible?

Model made by US researchers Does Mars water contain enough oxygen for life?

It was a scientific sensation. In July of this year, Italian astrophysicists announced that they had found evidence of a lake 20 kilometers wide and 1.5 kilometers deep under the ice of the south pole of Mars. The news of liquid water on the Red Planet made the experts sit up and take notice. After all, water is a basic condition for the creation of life as we know it.

The decisive factor is the amount of oxygen

However, the mere existence of liquid water does not automatically mean that aerobic life - that is, life for which the element oxygen is required - is also possible. So the question is: is the oxygen saturation of water on Mars so high that the amount is sufficient to enable aerobic life? And scientists have long denied that. As a reason, they cited that the atmosphere of the red planet is 160 times thinner than that of the earth and also consists mainly of carbon dioxide.

More oxygen than expected

Salts keep water fluid

The basis for the model is a hypothesis that was already provided by the Italian discoverers of the presumed liquid water reservoir under the ice of the south pole of Mars. The astrophysicists from Bologna suspected that dissolved perchlorates - i.e. chlorine salts - ensure that the water does not freeze despite icy temperatures of -75 degrees Celsius.

The US researchers led by JPL scientist Vlada Stamenković and Caltech geobiologist Woody Fisher followed this hypothesis. In doing so, they concluded that salty water could very effectively absorb oxygen from the thin atmosphere of Mars if it could only be found close enough to the surface of the Red Planet. To find out how much oxygen can be absorbed in liquid Mars water, the US scientists first developed a chemical model that describes how oxygen is dissolved in salt water below freezing point. Next, they developed a climate model of Mars for the past 20 million years. By combining the two models, they finally succeeded in drawing conclusions as to which Mars regions are or were particularly suitable for high oxygen dissolution.

Low altitudes and low temperatures

The researchers came to the conclusion that low altitudes (thick atmosphere) and low temperatures (gases such as oxygen can be more easily bound in liquids) are prerequisites for unexpectedly high amounts of oxygen to be bound in Mars water. This, they concluded, could even be above the limit that is necessary for aerobic respiration in the earth's oceans. The researchers found that the highest oxygen solubility in Mars water has occurred within the past five million years.

According to the US scientists, their results should provide better targets for future Mars missions in the search for earlier and currently existing habitable habitats on the Red Planet.