The theories

Why is oxygen surging on the Red Planet during spring and summer?

Molecules are breaking apart in the atmosphere One of the first considerations by scientists was the possibility that carbon dioxide (CO2) or water (H2O) molecules could be breaking apart in the atmosphere and releasing oxygen. This has now been ruled out because five-times more water would be needed, while CO2 breaks up too slowly to account for the surge in levels.

Solar radiation is breaking up oxygen molecules

It's one thing to work on the issue of a surge in oxygen and another to account for why in autumn the levels fall back to what is predicted. It was thought that solar radiation could be breaking the oxygen molecules into two atoms and that these were subsequently being blown into space, but such a process would take many years.

Martian soil is holding the secret

The most likely explanation is that hydrogen peroxide or perchlorates within the dirt of Mars are behind the surge.

Both are a source of oxygen, and it is possible that heat and humidity could draw it out during the spring and summer. This would need to happen on a large scale, but it is certainly a strong possibility.

The oxygen is being produced by aliens

Oxygen is associated with life, and it can be produced by living organisms such as microbes. Therefore there is a chance that oxygen is not being produced from the air or rocks and that a biological chemical reaction is taking place instead. It would be the most exciting explanation, but it’s one being ruled out – for now at least.