Finding traces of life – past or present – on Mars, this is why NASA sent the rover PerseverancePerseverance on the Red Planet. He has been surveying the Jezero crater for almost four years now for this purpose. And regularly, it returns hopeful data that researchers (and the media) seize upon with enthusiasm.
Incredible: Perseverance could have discovered the first fossil traces of life on Mars!
This time, it is the comment published in the journal Nature Astronomy by an astrobiologist from the Technical University of Berlin (Germany), Dirk Schulze-Makuch, who attracts attention. Because it raises the possibility that we could have been one step away from reaching the goal in the mid-1970s. But that, inadvertently, NASA would then have destroyed the traces of life hidden in the samples.
Experiments to find life on Mars 50 years ago
Let us recall that in 1976, the two Viking landers – the very first to land on Mars – aimed, among other things, to carry out some experiments designed to find biosignatures in Martian rocks. Understand, to find traces of molecules that would indicate the presence of an extraterrestrial life form. Different types of experiments had been implemented. The only direct experiments of this kind conducted on another planet so far.
But with hindsight, doubts have been expressed by researchers as to their relevance. One of them, for example, involved heating the samples which could very well have been fatal to the life they might have hidden. However, one experiment in particular returned a positive result for potential microbial activity in the samples. Scientists have debated this for a long time. To come to the conclusion that it must have been… a false positive.
Accidentally drowned life forms
Today, Dirk Schulze-Makuch is considering another option. According to him, VikingViking may have indeed discovered signs of life on Mars. But said life did not survive the water used to conduct the experiment.
The chances that life existed on Mars are diminishing
To understand, you need to know that at the time, astrobiologists still imagined that life needed water to thrive. Lots of water. However, researchers have learned more recently, life can find its way in a dry environment. And even very dry. “So what would happen if we poured water on Martian organisms adapted to droughtdrought ? Scientists pompously say that they would find themselves overhydrated. In reality, it would be like drowning them”explains Dirk Schulze-Makuch in his commentary. As proof, he puts forward the misadventure experienced by the bacteriabacteria indigenousindigenous of the Atacama Desert (Chile) – which he knows well having studied them a lot -, one of the driest places in the world. Bacteria, 80% of which have already been killed by torrential rains.
Taking his thinking a little further, the astrobiologist suggests that Mars could well be home to a form of life adapted to the dry conditions that reign there. In this case, rather than “follow the water” – which is the strategy adopted by NASA from the beginning in its quest for life on the Red Planet – we should think about following other compounds as well. Salts. Hygroscopic salts, in particular, like sodium chloride (our table salt which has also been found on Mars). Because in hyper-arid environments, life can draw water from the humidity of theatmosphereatmospherethanks to this type of salt.
But this, like the rest, remains theory. And what Dirk Schulze-Makuch wants above all, now that our knowledge of the Martian environment, in particular, has evolved, is the implementation of a mission to Mars which would carry several independent means of detecting life. from each other. Because there are many ways to search for it. Only then, he believes, could we arrive at a convincing conclusion.
