Two years that the Perseverance rover travels the surface of Mars. And still not the slightest trace of potential life. Researchers offer an explanation.
Two years ago, almost to the day, NASA’s Perseverance rover landed on Mars. Since then, he has explored the Jezero crater, reputed to have contained liquid water in the past. With the support of his faithful assistant, the Martian helicopter Ingenuity which is now more than 40 flights. Their main objective: to search for traces of life on the Red Planet. But for now… nothing!
Normal, believe today Cornell University astrobiologists (UNITED STATES). Because there has never been life on Mars? No. Because on the other hand, the instruments currently present on the surface of the Red Planet simply might not be sensitive enough to detect organic matter of biological origin in the rocks of Mars.
They came to this conclusion after working on sedimentary rocks found in a Jurassic fossil delta. On the side of the Red Stone region, in the Atacama desert (Chile). It is the oldest and driest desert on our Earth. And it thus resembles, geologically speaking, quite a bit like the Red Planet.
There, the researchers found many microorganisms of indeterminate classification – they talk about « microbiome sombre » –, possibly a mixture of biosignatures of current and ancient microorganisms. For this, they had to resort to state-of-the-art laboratory equipment. Which suggests to Armando Azua-Bustoslead author of the study, that “false negatives in the search for life on Mars are possible” with current instruments, putting “highlights the need for more efficient tools”.
Better tools on Mars or samples on Earth
According to the researchers, therefore, for “determine conclusively whether life ever existed on Mars”it will be necessary “either send complex instrumentation 53 million kilometers from our Earth, or bring Martian samples to our most advanced laboratories”. And it’s going pretty well. Since it is precisely the choice that was made by NASA. Samples that Perseverance recently deposited on Martian soil should be recoverable by the program Mars Sample Return. Even if it will still take a few years for that. They can then be analyzed by all the advanced methods available to researchers on Earth.
In 2028, the first European rover to land on Mars – that of the ExoMars mission, baptized Rosalind Franklin – will carry a drill with unprecedented capacity. She can probe to a depth of two meters. Enough to reach sediments probably better protected from the difficult conditions of the surface of the Red Planet.
It’s another choice. That of attempting, using more powerful tools, to question different samples. In which biosignatures could be better preserved, in greater abundance and with greater diversity. This ultimately leaves the instruments on board the rover more likely to detect them. And to finally provide an answer to the question we all ask ourselves: did life ever develop on the planet Mars?