The rocks on the surface of Mars have given scientists the best evidence that the planet had an oxygen-rich atmosphere in the past.
Recall that Mars got its nickname "Red Planet" because of the abundance of iron oxide on its surface, which has a reddish-red hue and is otherwise known as rust. NASA's Curiosity rover has also found significant amounts of manganese oxide in the rocks of Gale Crater.
“We found that three percent of the rock is manganese oxide. This substance requires a lot of water and strong oxidizing conditions for its formation, so that the atmosphere of Mars could contain much more oxygen than previously thought,”said Agnès Cousin of the Research Institute for Astrophysics and Planetology in France at the European meeting in Vienna. Geophysical Union (European Geophysical Union).
Mars' atmosphere today is 95 percent carbon dioxide and contains only trace amounts of oxygen. However, many researchers claim that it was once rich in oxygen.
And the new data from the Curiosity rover team is the most direct evidence to date.
The rover detected the presence of manganese oxide using the ChemCam tool, which breaks up rocks with a laser. It then analyzes the resulting dust cloud to determine the chemicals and minerals it contains.
So far, scientists have not been able to determine the exact age of manganese oxide (and thus when oxygen was present in the atmosphere of Mars), but they hope to do so by studying future data transmitted by the rover.
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Many manganese oxide deposits are located close to the place where a lake was once located in the crater under study. This liquid with oxygen dissolved in it may have played a role in the formation of the mineral, Cousin argues.
If there was too much oxygen there, it was probably not very good for early life, says Damien Loizeau of the University of Lyon. On Earth, oxidation destroys biological molecules. The appearance of oxygen on our planet was associated with the organisms that gave rise to it, but it was a disaster for other organisms that existed then, he concludes.