The surface of Mars, unlike the Earth’s, is not constantly renewed by plate tectonics, resulting in huge areas of terrain with fossil rivers and lakes, dating back billions of years (credit: NASA/JPL-CALTECH/MSSS/IRAP/RAPIN ET AL./NATURE)

The emergence of primitive life forms, as hypothesized by scientists, initially requires environmental conditions favorable to the spontaneous organization of these molecules into complex organic compounds. That’s what a research team from the Institut de Recherche en Astrophysique et Planétologie with their US and Canadian colleagues has discovered.

First fossil evidence of dry/wet seasons

Using the Mastcam¹ and the ChemCam² instruments on Curiosity, they found deposits of salts forming a hexagonal pattern in sedimentary layers dating from 3.8 to 3.6 billion years ago — the first fossil evidence of a sustained, cyclical, regular Martian climate with dry and wet seasons.

Independent laboratory experiments have shown that this kind of environment provides the ideal conditions for the formation of complex precursor and constituent compounds of life, such as RNA.

Large-scale images from orbit next

These new observations should now enable scientists to take a fresh look at the large-scale images obtained from orbit, which have already identified numerous terrains with a similar composition. They now know where to look for traces of the natural processes that gave rise to life, of which no vestiges remain on Earth.

Footnotes

1- https://mars.nasa.gov/msl/spacecraft/instruments/mastcam/

2- ChemCam was built by a French-US consortium under the responsibility of the Institut de Recherche en Astrophysique et Planétologie (CNRS/Université de Toulouse III – Paul Sabatier/CNES) and the Los Alamos National Lab (United States). In France, the design of the instrument was funded by the French space agency CNES, the CNRS, the French Alternative Energies and Atomic Energy Commission CEA, and a number of universities. Mars Science Laboratory is a NASA mission run by the Jet Propulsion Laboratory (USA), which designed and operates the Curiosity rover.

Citation: Rapin, W., Dromart, G., Clark, B. C., Schieber, J., Kite, E. S., Kah, L. C., Thompson, L. M., Gasnault, O., Lasue, J., Meslin, P., Gasda, P. J., & Lanza, N. L. (2023). 9-Aug-2023. Sustained wet–dry cycling on early Mars. Nature, 620(7973), 299-302. https://doi.org/10.1038/s41586-023-06220-3 

Original source: Mars: new evidence of an environment conducive to the emergence of life, Aug. 9, 2023, https://www.cnrs.fr/en/mars-new-evidence-environment-conducive-emergence-life

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