Right now, Marte It is a frozen desert in which, for the time being, no signs of life have been found. But this has not always been the case: in its early days, some 4.5 billion years ago, volcanic activity flourished on its surface. And it is discussed whether 3,700 million years ago, when life arose on Earth, something similar happened on our neighboring planet. Now, a study shows a theoretical model that indicates the possibility that the primitive Martian subsoil was inhabitable by beings that consumed hydrogen and produced methane. The conclusions have just been published in the journal ‘Nature Astronomy’.
This is not the first study that points to the hypothesis that the Red Planet was habitable in the past. Multiple investigations have pointed to the presence, millions of years ago, of oceans on its surface that could have supported life. In fact, vehicles like Curiosity or Perseverance search ‘in situ’ in places that scientists believe would have been covered with these liquid masses. However, not many models have been carried out that calculate the effective probability of this scenario.
Boris Sauterey, from the Institut de Biologie de l’Ecole Normale Superieure IBENS (Paris), and colleagues tried to simulate whether microorganisms consuming hydrogen and producing methane (the ‘diet’ of the first living inhabitants of Earth) could have survived on early Mars just below the surface, a few centimeters deep, where they would have been protected from the intense radiation hitting the ground directly. The bottom line is yes, “any ice-free place on Mars could have been riddled with these organisms,” says Sauterey.
The data goes further: these hypothetical Martian inhabitants would have produced “a biomass similar to that of the primitive ocean on Earth”; that is, a ‘population’ of living beings in the same proportion as the one that existed 3,700 million years ago under the waters of our planet. This ecosystem would have endangered the presumably hot and humid climate of early Mars because of so much hydrogen extracted from the thin, carbon dioxide-rich atmosphere. In turn, this would have caused temperatures to drop by nearly -400 degrees Fahrenheit (minus -200 degrees Celsius). As a consequence and in the face of climate change, these microorganisms would have had to seek habitats deep 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 below it.
“Although the work is based on theoretical climate and ecological models, (…) it gives us some interesting ideas,” he says for SMC Spain. Cesar Minor Salvan, Professor of Biochemistry at the University of Alcalá-. For example, differences in climate, geochemistry (such as salinity) and, above all, in the characteristics and composition of the atmosphere, conditioned the evolution of these ecosystems. Thus, while on Earth the activity of methanogens could favor habitability and the evolution of life, on Mars it could be the opposite, causing these organisms to globally cool the planet. Therefore, life on Mars had to continue below the surface, ever deeper, using geochemical processes as a source of hydrogen.”
For its part, Jesus Martinez Friasplanetary geologist and astrobiologist at IGEO (CSIC-UCM), points out that it is a theoretical model “of great quality and really interesting”, but “astrobiologically speculative”: “Considering an ‘ecological model’ of Mars, when there is no Even with no evidence of life or its potential biomarkers, it is an interesting exercise, with valid conclusions regarding what was suggested and the methodology used, but which would require greater solidity and scientific rigor, beyond what is purely theoretical”, he indicates.
Still, the authors point to three key places where future (or present) missions could find primitive life: Hellas Plains, The Plains of Isis and the Crater Lake. This last location is, according to scientists, the bed of an ancient lake in which the Perseverance rover is currently rolling, which is already taking samples that in a decade will be sent to Earth for analysis. Perhaps the trail of those Martian beings predicted by this theoretical model has been captured in them.