After great drum rolls which she has the secret, NASA said Monday it has tangible evidence of the actual presence of liquid water on Mars. What needs to think and what implications for research of a possible extraterrestrial life? Astrophysicist Francis Rocard, head of solar system exploration at CNES, decrypts, for The Point.fr, the real implications of this discovery.
The Point.fr : What the researchers observed precisely?
Francis Rocard: In 2011, the dark discharge, correlated to a seasonal effect, had been spotted on the slopes of Mars. Already, the idea had germinated in the minds of everyone that this could be related to a liquid water phenomenon. But still had to prove it! We were then told at the time that if we found salt, that would be proof. Now, with the instrument CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) of the probe MRO (Mars Reconnaissance Orbiter), the authors of the study released Monday identified perchlorate salt hydrates, that is to say waterlogged water. Hence the conclusion reached now is that, yes, it was rather a phenomenon that takes place in the presence of liquid water. First, because there is a correlation with the season: this happens when it’s hot and not when it is cold. And second, because we are dealing with salts that flow, which is consistent with liquid phase transition, knowing that these salts do not freeze to a temperature of – 23 ° C. However, this is not a direct proof of the presence of liquid water is only indirect evidence …
However, can we consider that it s ‘is d ‘ definitive proof?
Yes, this is an almost definitive proof, the only downside being that we have not formally observed in liquid phase water. It was, in short, observed hydrated salts in a consistent thermal context with the fact that it passes the liquid phase.
D Where this water can it come?
There are not really any answer to this question. However, you begin to master the history of water on Mars. We know that there are, in frozen form, almost everywhere, even if the concentrations in the soil are not necessarily well known. Think we have a ice accumulation on the soil starts to move in the liquid phase when it gets hot is a diagram that takes the road. In other words, it is not liquid water that comes out of the basement, as it triggers uniformly throughout an area and it is not located at a water seepage liquid.
The authors of study evoke an absorption of moisture in the ‘ Martian atmosphere, so tenuous it may be. Qu ‘do you think?
It is also an opportunity … It is true that there is a little water vapor in the Martian atmosphere, but really very little.
What are the real implications of this discovery for the search for life on Mars?
This is not an easy question. I think we will have now “digest” the news. Of course, liquid water is a prerequisite for the emergence, the emergence and preservation of life. It’s a certainty. Nevertheless, we are dealing with phenomena that are extremely liquid episodic, seasonal, and finally quite rare. So be careful enough. In addition, we speak of hydrated perchlorates, salts that are not very friendly for the living, although some chemists have ever imagined bacteria that can live in high concentrations of perchlorate. But anyway, for many reasons (radiation, cold, soil acidity, etc.), the environment on Mars today is hostile. So if life exists, it may be that damn resistant bacteria …
Finally, for you, s ‘is it d ‘a fundamental discovery?
I wonder about its importance. In the sense that we will see whether this discovery will influence the Mars exploration strategy. Will there be a consensus in the scientific community to say that, yes, it is very important. In 1976, the Viking exploration program sought a present life on Mars and gave no results. After that everything has switched to the search for ancient life dating from 3.5 to 4 billion years. Now, what are we going to decide to do? Change strategy? Do both in parallel? This is something that we will watch closely …
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