Mars is uninhabitable. This is not a scoop and has been the case for a long time. However, during its existence, the Red Planet must also have been adorned with blue and life could have developed there. This is what the Mars rover seeks to prove Curiosity on a mission to Mars since 2012.
But recently, it is not proof of the presence of a past life form that Curiosity put forward, but the reasons for the disappearance of water on Mars and therefore gradually the appearance of conditions which made it inhospitable.
The answer is in isotopes
It was by studying the composition of certain rocks on the surface of Mars that scientists were able to discover how water had disappeared. More precisely, and thanks to the instruments of Curiosityscientists carried out analyzes of the elements present in so-called carbonate sedimentary rocks.
These specific rocks are considered “climate archives”, as indicated in the NASA press release. In the same way that on Earth, their analysis allows us to know the climate that our planet experienced millions of years ago, scientists have done the same on Mars.
More precisely, it is the isotopic analysis of the elements (carbonates) trapped in these rocks which allows us to know what the Martian climate was like before. The isotopes analyzed are in fact the heavy residues of elements which have been dispersed in the atmosphere.
Thus, thanks to this analysis and the readings of Curiosityscientists were able to estimate that the reason for the disappearance of water on the surface of Mars was: evaporation. This is what David Burtt explains Goddard Space Flight Center from NASA.
“The isotopic values of these carbonates indicate extreme amounts of evaporation, suggesting that these carbonates likely formed in a climate that could only support transient liquid water.” we can read in the press release from the American space agency.
Samples that are “incompatible” with the development of life
Would Mars still have been uninhabitable? For the moment, it is impossible to provide a definitive answer to this question. Indeed, with regard to the analysis results, David Burtt who published his work in the journal Proceedings of the National Academy of Sciences (PNAS) on October 7, 2024, explained that the “samples are inconsistent with an ancient environment where life is present on the surface of Mars.”
In fact, it may be that the evaporation of water on Mars was not of considerable importance for the planet and its possible “inhabitants” since, according to the analysis of isotopes of carbonate rocks, it does not There was not a soul alive to be sorry.
However, the lead author of the study does not rule out two hypotheses. “This does not exclude the possibility of a subsurface biosphere or a surface biosphere that began and ended before the formation of these carbonates”. So, Curiosity notably made it possible to prove that life, as we know it, did not exist or no longer existed when water disappeared from Mars.
At this point, the Red Planet could therefore have been habitable at one point.
The future “habitability” of Mars
It's no secret that if the Moon is one of the short-term objectives of the main space agencies around the world, Mars is the planet that makes them dream in the long term. And not just space agencies.
Indeed, with the objective and the desire to make the human species a multiplanetary species, Elon Musk has the ambition to begin the colonization of Mars. And according to the eccentric billionaire founder of SpaceX, It shouldn't take too long anymore. During the month of September, he revealed on X (formerly Twitter) a forecast schedule of future missions to the Red Planet.
So, in 2026, SpaceX would launch an unmanned round-trip mission to Mars with a landing on the planet planned. If the mission is a success, the first manned mission to the Red Planet should take place in 2028, thus marking the possible start of its colonization.
Of course, until then, it will always be inhospitable to Man and the latter will have, if he manages to settle there, to live in bases closed to the outside world until a project to terraform Mars take a seat. But we are talking about a project that could last several thousand years and is not guaranteed to succeed.
In other words, while we may have the opportunity to witness the first man to walk on Mars, we will never, in our lifetime, see the planet become a place where life can develop.
Source: NASA
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