Microbes could have invaded the subsurface of ancient Mars

Microbes could have invaded the subsurface of ancient Mars

at this time, Marte It is a frozen desert where no signs of life can be found for the time being. But this was not always the case: in its early days, around 4.5 billion years ago, volcanic activity flourished on its surface. It is debated whether something similar happened on our neighboring planet 3,700 million years ago, when life arose on Earth. Now, a study presents a theoretical model that suggests the possibility that early Mars could have been habitable for terrestrial life. Hydrogen was consumed and methane was produced. The findings have now been published in the journalNatural Astronomy‘.

This is not the first study to point to the hypothesis that the Red Planet was once habitable. Multiple investigations have pointed to the presence of oceans that could have supported life on its surface millions of years ago. In fact, vehicles are preferred Curiosity O Persistence They search ‘in situ’ in places where scientists believe they may be covered by these fluid masses. However, many models that quantify the effectiveness of this scenario have not been implemented.

Boris Soutery, from the Institut de Biologie de l’Ecole Normale Superieure IBENS (Paris), and colleagues tried to simulate whether hydrogen-consuming and methane-producing microbes (the diet of Earth’s first living creatures) existed on early Mars. At the surface, a few centimeters deep, they would have been protected from the intense radiation that hit the ground directly there. In essence, yes, “any ice-free place on Mars could have been teeming with these creatures,” Souteri says.

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The data goes even further: the inhabitants of this hypothetical Martian would have produced “a biome similar to Earth’s primitive ocean”; That is, a ‘population’ of the same proportion of organisms that existed underwater on our planet 3,700 million years ago. This habitat would have jeopardized the early hot and humid climate of Mars because it extracted so much hydrogen from the thin carbon dioxide-rich atmosphere. That, in turn, would have caused the temperature to drop to about -400 degrees Fahrenheit (minus -200 degrees Celsius). As a consequence, and in the context of climate change, these microbes would have had to seek deeper habitats in the planet’s crust in an attempt to survive. In fact, some studies suggest that life, if it currently exists on Mars, would not be on the surface, but beneath it.

“Although based on theoretical climate and ecological models, (…) it provides some interesting ideas,” he says. SMC Spain Caesar Minor Salvan, Professor of Biochemistry at the University of Alcalá. For example, differences in climate, geochemistry (e.g. salinity) and, above all, in the characteristics and composition of the atmosphere, conditioned the evolution of these ecosystems. Thus, while the activity of methanogens on Earth favors habitability and the evolution of life, it may be reversed on Mars, with these organisms contributing to a global cooling of the planet. Therefore, life on Mars must have remained below the surface, using geochemical processes as a source of hydrogen.

As part of that, Jesus Martinez FriasA planetary geologist and astrobiologist at IGEO (CSIC-UCM) points out that this is a theoretical model, “of excellent quality and really interesting”, but “astronomically speculative”: “Considering an ‘environmental model’ of Mars, no. Although there is no evidence of life or its potential biomarkers, the methodology proposed and used “It’s an interesting exercise with valid conclusions, but it needs more rigor and scientific rigor than being purely theoretical,” he suggests.

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However, the authors point to three key places where future (or present) missions could find primitive life: Hellas Plains, Plains of Isis And Crater Lake. According to scientists, this last site Ancient lake basin The Perseverance rover is currently rolling on it, already taking samples that will be sent back to Earth for analysis within a decade. The trajectory of Martian life predicted by this theoretical model is probably imprinted on them.

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