Mars, our planetary neighbor with a similar geological history, has long been fascinated by Earthlings. Part of that is its proximity to Earth – which means it’s the most visited planet (by robots, at least); And part of that is because of a number of hopeful but faint signs that life may have been there. These hopeful signs span a series of flower-shaped boulders; for the presence of minor electrical surges; To the ever-present possibility that liquid water exists somewhere on Mars or may have once existed.
“It is possible that life appears regularly in the universe. But the inability of life to maintain habitable conditions on the planet’s surface is causing it to become extinct very quickly. Our experiment takes it a step further because it shows that even a very primitive biosphere can have a completely self-destructive effect.” “
However, a new research paper published in Nature Astronomy is an interesting introduction to the history of life on Mars. We know from geological evidence that the Red Planet underwent a major climate shift in its younger years, making it drier and less liquid. The cause of this climate shift is not well understood, and the above paper suggests that climate change, caused by gaseous emissions from life on Mars, may also have been devastated.
In a study by French and American researchers, scientists explain that life may have thrived in Martian rock (or loose dust and rock over a layer of bedrock) because it would have been filled with salt water and protected from ultraviolet and cosmic radiation. Of course, this was roughly 3.7 billion to 4.1 billion years ago, and the life in question would have resembled Earth’s microbes rather than anything particularly intelligent or sophisticated. However, these microbes could have thrived enough to consume hydrogen and carbon dioxide, both of which were present in the Martian burial at the time – and to release methane.
We know this because, on Earth, microbes like this are already found in hydrothermal vents, and they also release methane using a process known as methanogenesis. But because it does that in the ocean, little of the methane is released into that atmosphere, being absorbed to some extent by ocean water. These hypothetical Martian microbes would not have enjoyed this luxury, and the subsequent release of methane may have altered the planet’s atmosphere to the point that it eventually became hostile to microbes.
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“The projected change in atmospheric composition caused by methanogenesis would trigger a global cooling event, ending potential early warming conditions, harming surface habitability and forcing the biosphere deeper into the Earth’s crust,” the authors wrote. In order for future explorers to test their hypothesis, they add, they must target “low-to-medium-altitude lowland sites,” because these are areas where life forms behaving in this way are most likely to leave traces for humans to discover one day.
The life in question would have resembled Earth’s microbes rather than anything particularly intelligent or sophisticated.
Humans are well familiar with the idea of man-made climate change, for which there is scientific consensus that emissions of industrial civilization, especially carbon dioxide, are slowly altering the temperature of the planet. However, the idea of simple life, and perhaps even single-celled life, changing the planet’s atmosphere as much as it changed its climate is not so far fetched. In fact, something like this has happened at multiple points in Earth’s history. Between 2 billion and 2.4 billion years ago, algae converted a lot of carbon dioxide into oxygen to permanently change the composition of Earth’s atmosphere. The Great Oxygen Event, as it is known, also led to the formation of the protective ozone layer around the Earth, which protects life on Earth from harmful ultraviolet rays. Both events permanently altered the future evolutionary history of life on Earth, as well as the climate.
But while the Great Oxygenation Event made Earth more habitable for some life and less habitable for others (especially anaerobic bacteria), the possibility of Mars life making its planet inhospitable has a curious similarity to human behavior today. Man-made climate change is expected to raise sea levels, increase the number of epidemics, cause heat waves, make large areas of the planet uninhabitable, lead to more wildfires, and otherwise destroy life on Earth as we know it. The study authors did not lose sight of the similarities between Earth’s current predicament and one that may have existed on Mars billions of years ago.
“The components of life are everywhere in the universe,” astrobiologist Boris Sauterey of the Institut Biologie de l’Ecole Normale Supérieure (IBENS) in Paris, France, who led the research, told Space.com. “So it is possible that life appears regularly in the universe. But the inability of life to maintain habitable conditions on the planet’s surface is causing it to become extinct very quickly. Our experiment takes it a step further because it shows that even a very primitive biosphere can have a completely self-destructive effect.”
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Originally published at San Jose News Bulletin
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