Still valiant after 10 years of good and loyal service the rover Curiosity continues to survey the Martian soil in search of samples likely to arouse the curiosity of scientists (Curiosity, curiosity, bof…). And it seems that one of the last sample collections has kept its promises. After analyzing 24 samples from the Gale crater, NASA scientists have come to the conclusion that the pieces of rock recovered display a signature which, on Earth, would be qualified as…biological!
In detail, some of the samples recovered display carbon-13 isotope compositions that are far from the usual. This rock debris is indeed very poor in carbon 13, which on Earth is the signature of biological activity, generally of the microbial type. NASA researchers are well aware that Mars is not Earth, however, and are already preparing to evaluate scenarios “unconventional” which would eliminate the biological hypothesis.
One of these scenarios hypothesizes that the low carbon content could result from the passage of a galactic molecular cloud. This is not the most likely scenario given that the phenomenon would only occur every 200 million years and that it would be necessary in addition that Mars was mainly formed of glaciers at the time of the passage of the cloud. Also, analyzes of the Martian soil do not indicate that Mars was once a ball of ice or dotted with glaciers over much of its surface.
So there also remains the hypothesis of an extra-terrestrial biology, which after all needs to be evaluated on par with the others, knowing that according to the scientific approach, this approach is not far-fetched IN ITSELF (the Terrestrial biotope is the most compelling evidence). Scientists therefore consider that the particular signatures found on Mars may result from the activity of surface microorganisms which would have released methane. UV radiation could then have converted this methane into larger molecules which would have fallen to the surface of Mars.
NASA now hopes that the next samples will be able to provide other elements to decide between all of these scenarios.