Leonard David's INSIDE OUTER SPACE

Selfie taken by Curiosity Mars rover at Gale Crater.
Credit: NASA/JPL-Caltech

While “X” may mark the spot – on Mars consider hexagonal features that indicate an environment conducive to the appearance of life.

Researchers making use of the NASA Curiosity Mars rover at Gale Crater have discovered deposits of salts forming a hexagonal pattern in sedimentary layers dated to 3.8 to 3.6 billion years ago.

The muddy mix forms a hexagon pattern due to seasonal variations in humidity.

Hexagonal fossil pattern in sedimentary rocks analyzed by Curiosity on the 3154th day of its advance through Gale Crater on Mars.
Image credit: NASA/JPL-Caltech/MSSS/IRAP/Rapin et al./Nature

Long-lasting climate

The hexagons constitute the first fossil evidence of a cyclic, regular and long-lasting Martian climate, organized into dry and wet seasons.

This work opens up new thinking on the origin of life, the remains of which have long-since disappeared here on Earth.

The just-published research is led by William Rapin of the Institut de Recherche en Astrophysique et Planétologie (CNRS/Université de Toulouse III) in Toulouse, Occitanie, France, along with experts at CNES (the French space agency), together with U.S. and Canadian colleagues.

Favorable to prebiotic evolution

“Our findings point to a sustained, cyclic, possibly seasonal, climate on early Mars,” the research team reports. “Furthermore, as wet–dry cycling can promote prebiotic polymerization, the Gale evaporitic basin may have been particularly conducive to these processes.”

According to the  paper, the observed polygonal patterns are physically and temporally associated with the transition from smectite clays to sulfate-bearing strata, a globally distributed mineral transition.

Image credit: NASA/JPL/Caltech

Bottom line: “This indicates that the Noachian–Hesperian transition (3.8–3.6 billion years ago) may have sustained an Earth-like climate regime and surface environments favorable to prebiotic evolution,” the researchers conclude.

Ideal conditions

In a statement from the French National Center for Scientific Research (CNRS), similar to the hexagons observed in seasonally drying terrestrial basins, the features on Mars constitute the first fossil evidence of a cyclic, regular and long-lasting Martian climate, organized into dry and wet seasons.

“By allowing molecules to interact at different concentrations and repeatedly, independent experiments in the laboratory have shown that this environment provides the ideal conditions for forming complex compounds that are precursors and constituents of living organisms such as RNA.”

The Chemistry and Camera tool is known as ChemCam. ChemCam’s laser, camera and spectrograph work together to identify the chemical and mineral composition of rocks and soils.
Image credit: NASA/JPL-Caltech/Los Alamos

Fresh look

According to the CNRS statement, these new observations allow scientists to take a fresh look at the large-scale images obtained from orbit. Using that orbital imagery many terrains with a similar composition have been spotted. “They now know where to look for traces of the natural processes at the origin of life, of which no trace remains on Earth,” the CNRS statement explains.

This new research comes from use of Curiosity’s Chemistry and Camera (ChemCam), built by a Franco-American consortium under the responsibility of CNRS/University of Toulouse III – Paul Sabatier/CNES and the U.S. Los Alamos National Laboratory. In France, the design of this instrument has received support from CNES, CNRS, CEA and several universities.

Mars expedition probes the promise that Mars was a home address for past, possibly life today.
Credit: NASA

Fossil rivers and lakes

Since 2012, NASA’s Curiosity rover had already detected the presence of simple organic molecules that could be formed by geological or biological processes.

“Unlike the surface of the Earth, that of the planet Mars is not renewed by plate tectonics. It has thus preserved vast spectacular lands through the abundance of fossil rivers and lakes dating back several billion years,” adds the CNRS statement.

The research – “Sustained wet–dry cycling on early Mars” has been published in the journal Nature – at:

https://www.nature.com/articles/s41586-023-06220-3