Some people never stop dreaming of it, despite the hostility, the distance and the unknown: settling on Mars. Elon Musk, in particular, is convinced that he can achieve this – or even create a real colony that he would help grow by donating his sperm. But this implies knowing more things about this red planet, where terrestrial life as we know it seems impossible for the moment.
According to NASA, life may have existed in the past on Mars. The question that torments them is therefore to know why and how the appearance and climate of the planet have evolved to become what they are today. By analyzing the isotopic composition of carbon-rich rocks, carbonates, found in Gale Crater – which the Curiosity robot has been exploring since 2012 – scientists have found some answers.
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The importance of carbon isotopes for analyzing climate
If researchers have looked at carbonate isotopes, it is because they make it possible to trace previous versions of the same element, thanks to their mass. Isotopes are atoms that do not have the same number of neutrons as others; their atomic mass is therefore different.
NASA scientists relied on carbon and oxygen isotopes to determine whether there is water on Mars, to what extent and in what form. “The isotopic values of these carbonates tend to demonstrate the hypothesis of extreme levels of evaporation, which suggests that these carbonates were formed in an environment where water in the liquid state was only ephemeral”notes David Burtt, one of the authors of the study, published October 7 in Proceedings of the National Academy of Sciences.
NASA researchers doubt the existence of past life on Mars
For researchers, this discovery makes the presence of a form of life on the surface of Mars concomitantly with the formation of these carbonates improbable. “This does not mean that a biosphere did not exist underground or on the surface before these carbonates formed”souligne David Burtt.
For scientists, the carbonates could have formed under two distinct scenarios: either as part of wet then dry cycles within Gale crater, or in very salty and icy water. If the second scenario is correct, the hypothesis of the presence of life on Mars in the past seems strongly compromised. Elements to explore to understand the past but also to consider a possible Martian future.
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