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Ancient Mars may have had an environment capable of hosting an underground world full of microorganisms, scientists report.
But if they existed, the researchers concluded, these simple life forms would profoundly alter the atmosphere, triggering a Martian ice age and killing themselves.
The findings offer a bleak view of how the universe works.
Life, even a simple one like a microbe, “may in fact often cause its own death,” said the study’s lead author, Boris Sauterey, now a postdoctoral researcher at the Sorbonne University in France.
The results “are a bit frustrating, but I think they’re also very stimulating,” he said. “They challenge us to rethink the way the biosphere and its planet interact.”
In a study in the journal Nature Astronomy, Sotre and his team said they used climate and topographic models to assess the habitability of the Martian crust about 4 billion years ago, when the red planet was thought to be filled with Water, more livable than it is today. .
They speculate that hydrogen-absorbing, methane-producing microbes may have thrived beneath the surface, with dirt a few inches (tens of centimeters) thick enough to protect them from the intense incoming radiation.
According to Sotre, any ice-free place on Mars could host these creatures, as they did on early Earth.
However, Sotri said early Mars’ likely wet, warm climate would have been compromised by large amounts of hydrogen being sucked out of a thin, carbon dioxide-rich atmosphere.
With temperatures plummeting by nearly minus 200 degrees Celsius, any creature at or near the surface could bury deeper to survive.
In contrast, given the nitrogen-dominated atmosphere, microbes on Earth may help maintain temperate conditions, the researchers said.
Kaveh Pahlevan of the SETI Institute said that future models of the Martian climate would need to take into account the French study.
Another recent study led by Pahlevan showed that Mars was born wet with warm oceans for millions of years.
His team concluded that the atmosphere at the time would have been dense, mostly hydrogen, as a heat-trapping greenhouse gas that was eventually transported to higher altitudes and disappeared into space.
The French study, which investigated the climate impact of microbes that might have existed when the Martian atmosphere was dominated by carbon dioxide, was not applicable earlier, Pahlevan said.
“However, their study clearly shows that if (this) life existed on Mars” in the early stages, “they would have had a significant impact on the climate at the time,” he added.
The best place to find traces of past lives? French researchers have proposed the unexplored Hellas Planita or plain and Jezero crater on the northwestern edge of the Isidis Plain, where NASA’s Perseverance rover is currently collecting rocks for return to Earth in a decade.
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