Mars, difficult to find signs of life with current instruments

Discovering traces of life on Mars will be more difficult than expected, because the instruments for detecting biological traces already present on the planet or in the design phase may not be sensitive enough: to get an answer, we will therefore have to wait for the samples to arrive on Earth collected by the Perseverance rover. This is the conclusion of a study published in the journal Nature Communications by an international team in which the National Institute of Astrophysics (INAF) also took part.

The researchers tested the investigative tools of the Martian missions by analyzing samples collected in one of the driest places on our planet, Piedra Roja in Chile. It is an alluvial fan formed in arid conditions in the Atacama Desert about 160-100 million years ago and geologically similar to the Jezero crater on Mars where the Perseverance rover is located.

“We dealt in particular with the analysis of the samples using the Fourier transform infrared spectroscopy technique of diffuse reflectance”, explains Teresa Fornaro of the Inaf of Florence. “This allowed us to analyze the samples in a similar way to aboard Martian missions, such as the Perseverance rover’s SuperCam instrument and the MicrOmega instrument that will fly on the European Space Agency’s (ESA) Rosalind Franklin future ExoMars mission. Our analyzes confirmed the mineralogical composition of these rocks, but the detection of organic compounds was mainly possible in the mid-infrared spectral region which does not correspond to that investigated by the SuperCam and MicrOmega instruments. Therefore, the ability of these instruments to detect organics on Mars in concentrations as low as those of Piedra Roja is limited”.

From the analysis of the DNA of the microorganisms present in the rocks of the Chilean desert, a particularly interesting data emerged: about 9% was unclassifiable, while about 41% it was possible to assign only the domain or at most the order, putting evidence that the evolutionary kinship relationships with respect to known terrestrial organisms are not clear. They are believed to be either living species that have not yet been identified elsewhere on Earth, or alternatively surviving communities of microbial species that once inhabited the river delta, but for which no currently existing parent species are known.

“The region in which these samples were taken – underlines John Brucato, astrobiologist of the INAF of Arcetri and one of the signatories of the article – is the driest desert that can be found on Earth and these microorganisms seem to be really peculiar and very different from all the others known so far, if we consider that the quantity of microorganisms is so high that different ones are continuously discovered.In this case, it is a truly new class that has made it possible to understand their adaptability in extreme conditions that can make them consider similar to the Martian ones”.

Source: Ansa

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