The bacteria “Conan”, super-resistant to radiation, could survive millions of years on Mars

Bacterial strains on Mars are adapted to survive extreme conditions. But the “Conan” is not far behind. The ancient bacteria of Mars could survive near the planet’s surface for much longer than previously thought and, if they are also buried and thus protected from cosmic and solar radiation, they could survive even longer. This finding -published in the journal Astrobiology- raises the possibility that, if there was ever life on Mars, its biological remains could be recovered by the ExoMars (ESA) and Mars Life Explorer (NASA) missions, sent to Earth for examination. study, and pollute our planet. But the implications of the research go further: if the bacterial strains are able to survive in an environment as harsh as that of Mars, astronauts and future space tourists could also contaminate the red planet with their bacteria.

The article, led by Northwestern University (United States) and whose details are published today in the journal Astrobiology, warns that terrestrial contamination on Mars could last for thousands of years. The Martian Bacteria “Conan” Conditions on Mars are extreme: The planet is arid, very cold (it averages -63 degrees Celsius in mid-latitudes), and is constantly bombarded by intense cosmic and solar radiation. To test whether life could survive under these conditions, the researchers determined the limits of survival of microbial life to radiation and then subjected six types of terrestrial bacteria and fungi to similar conditions. Thus, they observed that some terrestrial microorganisms could survive on Mars during geological time scales of hundreds of millions of years. The researchers discovered that a robust microbe, Deinococcus radiodurans (nicknamed “Conan the Bacteria”), is uniquely suited to survive the harsh conditions on Mars. In the experiments, Conan survived astronomical amounts of radiation in a frigid and barren environment. In previous studies, the researchers had found that the Conan bacterium, when suspended in liquid, can survive 25,000 radiation (or “gray”) units, the equivalent of about 1.2 million years just below the surface of Mars. . The new study found that when the bacterium is dried, frozen and buried deep – which would be typical of a Martian environment – it could withstand 140,000 grays of radiation, a dose 28,000 times that which would kill a human.