Has the atmosphere of Mars ever had a lot of oxygen?

In 2014, the Curiosity rover identified somerocks located in the Gale and Endeavour crater have a high content of manganese oxide. It could only appear as a result of the oxidation process, which means that some kind of oxidizing agent, and quite a strong one, acted on the Martian rocks. In the Earth's atmosphere, this oxidizing agent is oxygen. This immediately gave rise to the version that there was once a lot of oxygen in the atmosphere of the red planet. But this gas could not arise by itself. For example, on Earth, this happened 2.5 billion years ago only thanks to cyanobacteria. Moreover, according to scientists, the Moon played a significant role in this, which increased the daylight hours, as we talked about earlier. Was it possible that oxygen life once existed on Mars too, or did manganese still oxidize as a result of exposure to some other substance? American scientists tried to answer this question in a recent study.

In some rocks, the rover found oxidized manganese, which may indicate that Mars once had an oxygen atmosphere.

Why there might not be oxygen on Mars

Oxygen, of course, is far from the onlyan oxidizing agent capable of oxidizing manganese. Therefore, back in 2014, in addition to the “oxygen” version of manganese oxidation, other hypotheses were also proposed. For example, oxygen-containing compounds of chlorine and bromine could react with manganese.

There are many such compounds on the red planet.more than on Earth. Therefore, they could well “oxidize” the manganese in the rocks. In particular, the Martian soil contains a large amount of perchlorates. These oxidizing agents are so strong that they are even used as part of solid rocket fuel. That is, theoretically, everything could have happened without a huge amount of cyanobacteria.

Oxygen in large quantities in the Earth's atmosphere appeared due to cyanobacteria

But the best confirmation of any hypotheses, asknown are practical experiments. Therefore, a group of American scientists decided to reproduce the process of manganese oxidation under different conditions using various oxidizers.

Why did manganese oxidize on Mars?

According to scientists, oxygen in Martian conditionsoxidizes manganese extremely slowly. This suggests that he needed much more reactive oxidizing agents for oxidation. These are the aforementioned bromine and chlorine compounds. Studies have shown that under the conditions of Mars, they turned out to be the most effective. The team reported in their study, published in the journal Nature Geoscience.

There was a lot of water on the surface of the red planet, which probably contained oxidizing agents.

Bromine and chlorine compounds could arise fromchlorides and bromides, which got into the atmosphere, where they oxidized under the influence of ultraviolet radiation. Then they ended up in water and, together with it, penetrated into the cracks of rocks, where they reacted with manganese. Recall that Mars once contained a lot of water. Moreover, according to the latest data, it remained here even longer than scientists expected.

Subsequently, together with water, chlorides and bromidesagain fell into the atmosphere, as a result of which the cycle was repeated. Confirmation of this version is that in the course of the experiments, a manganese oxide mineral called nsutite was deposited. Its spectrum is similar to the dark accumulations of manganese found on Mars.

Bacteria on Mars could exist without oxygen

Could life exist on Mars?

According to the results of the study,manganese-containing rocks, most likely, oxidized without any oxygen, and therefore without life on the planet. However, this does not mean that there could be no oxygen on Mars at all. Scientists have only shown how manganese oxides could form under geochemical conditions on early Mars. But, even if there really was no oxygen in the atmosphere, this still does not refute the possibility of the existence of life as such.

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On Earth, as we said above, first originatedoxygen-free life, and only then, thanks to it, an oxygen catastrophe occurred. That is, cyanobacteria enriched the atmosphere with oxygen. Accordingly, if life appeared on Mars, it did not need oxygen. The rest of the conditions for the emergence of life were quite acceptable.

For example, it has recently been found that the magnetic fieldexisted much longer than scientists originally thought. So life had time to be born. Moreover, there is an opinion that life did not just originate, but caused a catastrophe on Mars, destroying the atmosphere. Although some of the bacteria could still survive in the bowels of the planet. So the search for life continues.