The primordial soup of Mars: a discovery that makes the universe more and more known

For a very, very long time, the universe was seen as an environment in which the synthetic processes necessary to get from simple precursors to complex molecules based on carbon and typical of the constitution of living organisms could hardly and only in particular sites be generated.

For many decades, initially starting from the analysis of carbonaceous meteorites, and then gradually continuing up to the spectroscopic examination of the atmosphere of planets and other celestial bodies, nebulae and interstellar space, sInstead, an immense variety of chemical processes and organic molecules is foundamong which, coincidentally, those at the basis of biochemistry are ubiquitous – sugars, amino acids and small peptides, lipids, alcohols, nucleobases, etc.

In particular, many compounds found on Mars have been added to the inventory, first on meteorites from that planet and then directly on samples of the Martian soil. In the case of the red planet, this is particularly interesting, because in the past it was a blue planet, covered by vast expanses of water and with a sufficiently dense atmosphere to allow its stable existence; under these conditions, of course, the organic chemistry that was able to develop is more reminiscent of what happened on our own planet at the time, and that is why its study through exploration programs of its surface is particularly interesting.

What was in the “primordial soup” of Mars, when water covered large portions of its surface billions of years ago?

We already know that many organic molecules were formed during that time; to confirm, over 100 samples arrived from 10 different sites and analyzed by the SHERLOC system of the Perseverance rover.

Perseverance has explored the margins of a geological formation called “Seitah”, which is of particular interest, because it is composed of lava effusions, whose minerals crystallized and were then infiltrated/washed away by water. As had already been demonstrated, this of course altered their chemical composition, generating a large variety of sulphates, carbonates, silicates and chloride and hydroxychloride minerals, among which salts of different metallic composition are mixed. Why is this mineralogical variety interesting? Because many different minerals, in the presence of simple carbon compounds and water, are able to favor the formation of complex organic molecules; consequentially, the researchers thought of sampling the Seitah margin using a particular instrument of the rover, the aforementioned SHERLOCwhich, thanks to Raman and fluorescence spectroscopy investigations, is able to reveal the possible presence and diversity of complex organic compounds – those from which, at least on our planet, prebiotic evolution originated.

The results of the chemical investigation using SHERLOC are really interesting, and have just been published.

Associated with the sampled minerals, the researchers were able to identify many different classes of specific organic molecules, corresponding to the obtained Raman and fluorescence spectra; qThese mineral-organic molecule complexes show diversity in their distribution and composition, indicating potentially different fates of carbon in different mineral environments – i.e. great diversity of chemical processes at work and, consequently, great molecular variety produced. There is also a notable variety of aromatic molecules, and these materials have endured to this day despite exposure to Martian surface conditions.

The identified organic molecules they are found largely within minerals related to aqueous processesso that water must have played a very important role either in their synthesis, in their transport to specific sites, in their conservation for long times or, more probably, in all these phenomena, exactly as it is expected to have occurred in the Earth primordial.

Inorganic analysis also brought a new, fundamental element: in addition to the organic molecules and minerals listed which were already known, phosphates have also been found in the mixturethe. Given the fundamental role of phosphorus and phosphates in terrestrial life (as a skeleton of nucleic acids and as the main bond for storing metabolic energy in all living things), the presence of a chemically complex mixture of carbon compounds together with phosphates (and also sulphates) is once again compatible with environments and processes hypothesized for the primordial Earth which, in the laboratory, provided synthetic ways to obtain the first Darwinian replicators; this also remembering that nitrogenous organic molecules have been found elsewhere on the surface of Mars.

I believe that to fully grasp the potential value of these findings, it is helpful to consider the words spent by the researchersafter analyzing the data:

“Confirmation of organic origin and specific identification of these molecules will require the samples to be returned to Earth for laboratory analysis. However, these results indicate that a more complex organic geochemical cycle may have existed than described by previous in situ measurements on Mars, as evidenced by several distinct groupings of possible organics. In summary, the key building blocks for life may have been present for a long time (from at least about 2.3-2.6 billion years), along with other as-yet undetected chemical species that may be stored within of these two potentially habitable palaeo-depositional environments in the Jezero crater.”

Maybe life on Mars never happened; but what lies between organic chemistry and Darwinian replicators appears increasingly widespread in the universe, including the ancient seas of the red planet.