Primitive life forms thrived on Mars around the same time prehistoric life was developing in Earth’s oceans — but the Red Planet’s denizens doomed themselves, a new study suggests.
Mars’ microorganisms were likely flourishing just under its crust, gobbling up the hydrogen in its atmosphere, around 3.7 billion years ago, according to the study published in the scientific journal Nature on Monday. But the depletion of the planet’s hydrogen may have caused an ice age that led to their extinction, the study says.
“The ingredients of life are everywhere in the universe,” the study’s author, Sorbonne University post-doctoral researcher Boris Sauterey, told Space.com. “So it’s possible that life appears regularly in the universe. But the inability of life to maintain habitable conditions on the surface of the planet makes it go extinct very fast.
“Our experiment takes it even a step farther as it shows that even a very primitive biosphere can have a completely self-destructive effect.”
Mars’ once-moist and warm climate was conducive to life billions of years ago, around the same period when simple life forms were developing in Earth’s prehistoric oceans, the study notes.
But the Red Planet was significantly cooled off by the microbes’ consumption of hydrogen and excretion of methane, which contributed to the thinning of its carbon dioxide-rich atmosphere.
While temperatures on Mars could have been between 14 and 68 degrees, they may have plummeted by about 400 degrees when the planet’s once-dense atmosphere was depleted of the greenhouse gases carbon dioxide and hydrogen that it relied on to warm the planet, the study says.
The increasingly inhospitable climate would have caused the early Martian life forms to recede deeper into the crust of the planet to survive over a period of hundreds of millions of years, the research says.
Ultimately, they would likely have doomed themselves — raising “a bit gloomy” but also a “very stimulating” issue, the study says.
“They challenge us to rethink the way a biosphere and its planet interact,” Sauterey said.
Meanwhile, during the same period, microbes on Earth some 68 million miles away may have helped foster a warmer climate that supports complex life because our planet is dominated by nitrogen, scientists said.
“On ancient Mars, hydrogen was a very potent warming gas because of something we call the collision-induced absorption effect where molecules of carbon dioxide and hydrogen interact with each other,” Sauterey said.
“We don’t see that on Earth because our planet’s atmosphere is not as rich in carbon dioxide as that of Mars used to be. So the microbes essentially replaced a more potent warming gas, hydrogen, with a less potent warming gas, methane, which would have had a net cooling effect.”
Researchers said the findings support the theory that microbial life may still be present deep in the Martian crust and may have survived near the surface of the planet’s warmest regions such as Hellas Planita, Isidis Planitia and Jezero Crater — once the site of a lake system, where NASA’s Mars Preservation rover is collecting rocks.
On Thursday, the rover gathered samples that indicated signs of microbial life were once present in Jezero Crater, NASA said.
“The places on the planet where those microbes would have been closest to the surface would have been the warmest regions,” Sautery said.
“And the warmest places are usually the deepest places. At the bottom of these craters and valleys, the climate is much warmer than on the rest of the surface, and that’s why it would be much easier to search there for evidence of these life forms.”
With AP