Ancient cracks on Mars show that it had favorable conditions for life

Ancient cracks on Mars show that it had favorable conditions for life

The dilemma of whether it existed life ever on Mars it is renewed in each scientific study that is done in situ on the red planet or at a distance from Earth with the analysis of different photographs and telescopic observations.

While today, the planet is frigid, dry and inhospitable, Billions of years ago, water flowed through rivers and filled lakes in today’s craters recorded in their topography.

Now The discovery of distinctive mud cracks on the surface of the planet suggests that ancient Mars went through sustained cycles of wet and dry seasons for millions of years. Scientists say not only would the climate have been habitable, but cycling could also have given a boost to the basic chemistry of life.

The finding, published in the journal Nature, “is compelling evidence for the primitive existence of an Earth-like climate on Mars and presents thought-provoking theories about the origin of life on the Red Planet,” said Amy Williams, a geologist at the University of Florida who was not involved in the study.

The surface of Mars, unlike that of Earth, is not constantly renewed by plate tectonics. This has resulted in the Preservation of huge areas of remarkable land for its abundance of fossil rivers and lakes dating back billions of years.

Since 2012, the NASA’s Curiosity rover, the first rover to explore such ancient remains, had already detected the presence of simple organic molecules that can be formed by geological and biological processes.

However The rise of primitive life forms, according to the hypothesis of scientists, initially requires Favourable environmental conditions for the spontaneous organization of these molecules into complex organic compounds. Such conditions are precisely those recently discovered by a research team from the Institut de Recherche en Astrophysique et Planétologie (CNRS/Université de Toulouse III – Paul Sabatier/CNES) and the Laboratoire de Géologie: Terre, Planètes, Environnement, together with American and Canadian colleagues.

In the 1990s, NASA satellites orbiting Mars began capturing ravines, dry river deltas and layered sedimentary deposits, all of which require liquid water to form. “These geological features suggest that the ancient Martian climate was much warmer and wetter than it is today,” said Ashwin Vasavada, Curiosity rover project scientist at NASA’s Jet Propulsion Laboratory (JPL).

The question is How the early Martian climate may have allowed these hot and humid conditions persist long enough for life to take hold. Today, the Cold, thin atmosphere of the planet It means that what little water you have is locked up in frozen ice caps or minerals in the crust. According to Vasavada, conditions would have been even less favorable billions of years ago, when the Sun was much dimmer.

Some scientists believe that volcanic eruptions and asteroid impacts occasionally injected greenhouse gases into the atmosphere, triggering brief warm periods in an otherwise cold and dry climate. Other researchers say that Geological features demand a sustained warm and humid climate. “Early Martian geology was not the result of a sudden, transient warming event,” said Ramses Ramirez, a planetary scientist at the University of Central Florida.

Now, the Curiosity rover has discovered hexagon-shaped crack patterns in ancient rocks that add to evidence of a sustained warm climate. They resemble patterns found on Earth in places like Death Valley., where they only form after years of wet and dry cycles. When these cracks initially appear, they are square, with sharp T-shaped angles, explained lead author William Rapin, a planetary scientist at the French Research Institute in Astrophysics and Planetology.

Using the instruments Mastcam and ChemCam on Curiosity, have discoveredErto deposits of salts that form a hexagonal pattern in sedimentary layers dating from 3.8 to 3.6 billion years ago. Similar to hexagons observed in land basins Drying seasonally, they are the first fossil evidence of a sustained, cyclical and regular Martian climate with dry and wet seasons. It’s that every time the mud is rehydrated, the cracks “heal,” only to reopen when the soil dries out again. Over time, the acute angles soften into a Y-shape, producing the characteristic hexagons.

It is impossible to make this hexagonal pattern without regular periods of humidity and drought.Rapin, who believes these cycles may have persisted seasonally for thousands or millions of years. The finding dispels the notion that early Mars experienced only sporadic periods of heat. caused by catastrophic events, since according to the author, you can’t do that with volcanoes or meteorite impacts.

By allowing molecules to interact repeatedly at different concentrations, experiments by independent laboratories have shown that this type of environment provides ideal conditions for the formation of complex precursor compounds and constituents of life, such as RNA.

These new observations should allow scientists to take a fresh look at large-scale images obtained from orbit, which already They have 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 there are no vestiges left on Earth.

Such a wet-dry cycle could also have helped kick-start life. Life tends to use long chains of molecules called polymers. Water is required to build these chains, But too much water will prevent the molecular components from sticking together. The wet-dry cycle, which strikes a balance between the two conditions, could have been key to the “habitability and development of life,” said study author Nina Lanza, a planetary scientist at Los Alamos National Laboratory.

Still, The discovery produced “more questions than answers,” said study author Edwin Kite, a planetary scientist at the University of Chicago. Scientists still don’t know, for example, what made the climate of early Mars so warm or why the planet eventually dried up forever.

But Curiosity’s discovery could advance our Understanding the origin of life in our world. As Rapin sees it, ancient rocks from Mars have evidence of what has been lost on Earth. Just as geological processes in Earth’s Death Valley informed the analysis of mud cracks on Mars, so too knowledge of Mars can help researchers understand how life began on our own blue planet.

“The origin of life remains a mystery. We could go to Mars to help solve that mystery,” Rapin concluded.


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