New organic traces discovered on Mars

Traces of sulfate-associated organic compounds have been detected in samples taken from the Jezero crater on Mars. This is the result of a study conducted by the research team involving Paola Manini of the Department of Chemical Sciences at the University of Naples Federico II, based on data collected by the Sherloc spectrometer aboard NASA's Perseverance rover.

It cannot be ruled out that the organic molecules are residues from the degradation of ancient microbial matter, although the most likely origin is considered abiotic, more specifically through reactions of magmatic gases with iron oxides present in volcanic rocks.
The study, conducted by the research team led by Teresa Fornaro of the National Institute of Astrophysics (Inaf), was published in the journal Nature Astronomy.

The search for organic molecules on Mars is central to understanding whether the planet ever offered conditions conducive to life, and Jezero Crater, an ancient delta area that once held a lake and may have had high potential for habitability, is now one of the most interesting places to study. Here, the Sherloc (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) instrument aboard the Perseverance rover has detected strong and complex Raman signals associated with sulfates, particularly in the areas called Quartier and Pilot Mountain, on the crater floor and delta fan, respectively.

To test the hypothesis that the observed signals were indeed due to organic molecules, the team conducted experiments at Inaf's Astrobiology Laboratory in Florence, Italy. Martian analog materials and Sherloc-like instruments were used, reproducing natural processes under controlled conditions. This approach made it possible to acquire a reference dataset to compare with data acquired in situ, which is essential for correctly interpreting the complex signals from Mars. Based on these investigations, it was possible to assign the spectroscopic features detected by Perseverance to polycyclic aromatic hydrocarbons preserved within sulfates.

Although it cannot be ruled out that these organic molecules are residues resulting from the degradation of ancient microbial matter, however, the detection in volcanic rocks suggests that polycyclic aromatic hydrocarbons may have been formed through magmatic processes and later mobilized by water and trapped in sulfates. Circulating fluids, including possible hydrothermal waters, would have promoted their selective accumulation and storage in Jezero crater rocks.

These findings add to previous evidence from meteorites and Gale crater, reinforcing the role of sulfates in the preservation of Martian
Martian organic matter.

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