Mars: new traces of an environment conducive to the appearance of life have been discovered
Caption: Illustrative image of patterns left in dry rivers on Earth, somewhat similar to fossilized (hexagonal) patterns identified in sedimentary rocks analyzed by Curiosity, in Gale Crater, Mars / Image credit: Shutterstock
Just over a decade ago, NASA announced that the Curiosity rover had discovered ancient rivers on Mars that may have made parts of the planet habitable by microbial life. This hypothesis still remains to be proven.
Today, scientists from the CNRS, the University Toulouse III – Paul Sabatier and the University Claude Bernard Lyon 1 announce in a press release that they have identified new traces of an environment conducive to the appearance of life on the red planet. This discovery is presented as opening the way to new research perspectives on the origin of life .
Highlighting complex organic compounds precursors of life on Mars
The Guardian reported in 2013 that the Curiosity rover had discovered clays, and other substances including calcium phosphate, which suggested that the soil was neutral or slightly alkaline, making the environment conducive to microbes… therefore, to ' 'life''. However, the CNRS press release stresses that the emergence of primitive life “ first requires environmental conditions favorable to the spontaneous arrangement of these elements into complex organic compounds ”.
It is particularly in this sense that the publication published in the journal Nature completes our knowledge of the conditions potentially conducive to life on Mars . CNRS researchers have identified “salt deposits forming a hexagonal pattern in sedimentary layers 3.8 to 3.6 billion years old”. Chemcam, a ''Franco-American'' instrument on board the Curiosity rover, which uses the technique of spectroscopic analysis induced by laser ablation (LIBS) to carry out the elementary examination of rocks and soils was thus decisive.
The team from the Astrophysics and Planetology Research Institute of the University of Toulouse III – Paul Sabatier and the Geology Laboratory of Lyon, have made the connection between the deposit of salts and their pattern, and similar patterns on Earth , in the bottoms of dry rivers (seasonally). Laboratory experiments followed, allowing the molecules to interact at different concentrations and repeatedly. This “ showed that this environment offers the ideal conditions for forming complex precursor and constitutive compounds of life such as RNA ” …a complex molecule.
The discovery of the first fossil evidence of a cyclic Martian climate, similar to that of Earth
Beyond its contribution to the quest for the mystery of "the origin of life", these salt deposits and their hexagonal pattern constitute a highlight in themselves: they would be the first fossil witnesses of a similar Martian climate. to that of the Earth. Based on these patterns, the researchers argue that they indicate a ' cyclical, regular and long-lasting Martian climate, organized into dry and wet seasons '. It is moreover with the postulate of the variations of such an environment that the experiments in laboratory gave the results according to which, this environment would offer the ideal conditions for the appearance of the life.
Légende : Motif fossile hexagonal dans les roches sédimentaires analysées par Curiosity au 3154e jour de sa progression dans le cratère de Gale sur Mars / Crédit images : NASA/JPL-Caltech/MSSS/IRAP/Rapin et al./Nature
Cela ne veut cependant pas dire que la vie se soit produite, mais bien qu’elle aurait pu se produire, selon cette nouvelle publication. De manière plus générale, ces nouvelles avancées permettront aux scientifiques de revisiter les images précédentes obtenues de la planète rouge, et de prêter davantage attention aux terrains à composition similaire. Cela a un intérêt non seulement pour notre compréhension de Mars, mais aussi pour déceler les mystères de notre propre planète, dépourvue de traces aussi intactes, à cause de la tectonique des plaques.
Sources :
Communiqué du CNRS du 7 juillet 2023
The Guardian
Nature