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Would life on Mars be lurking deep under the ground?

Artist image of NASA’s Insight lander on the surface of Mars. Insight landed on Nov. 26, 2018, to study Mars’ internal structure and composition.
(NASA/JPL-Caltech)

WASHINGTON — To find life on Mars, scientists may need to specify surface exploration, and “go deep.”

Usually missions to Mars to search for signs of life purpose, the surface of the planet, in places where there are signs of the old water (a reliable indicator of where life is found on Earth). But while no life on the Mars surface, there are a plethora of microbial Martians congregating underground, according to research presented Dec. 11 here at the annual meeting of the American Geophysical Union (AGU).

In the past few decades, explorations underground on Earth has shown that the so-called deep biosphere — a underground area filled with micro-organisms. And scientists suspect that a similar organic-rich zone may be thriving under the martian surface. [Mars-like Places on Earth]

In fact, perhaps there was never an evolutionary pressure to inhabit the surface of Mars at all, Joseph Michalski, a senior lecturer at the Department of Earth Sciences at the University of Hong Kong, said at the presentation. The expectation is that life evolved on the Martian surface may indicate a deviation determined by what we know about life on our planet, Michalski said.

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Billions of years ago, when the planets in our solar system were young, the surface of Mars is probably similar to that of the Earth, the rocks neighbor. That all changed when Mars lost its magnetic field, which is exposed to a bombardment of intense radiation that would have made the survival of above-ground very challenging, Michalski told Live Science.

However, it is possible that life is already “cooking” on Mars before that happened. Scientists think that life first appeared on Earth approximately 3.8 billion to 3.9 billion years ago, when conditions in some places probably looked like today hydrothermal conditions — just as Mars in the time. Perhaps, life arose on Mars at the same time that it is the shape of the Earth, but adapted exclusively to life underground, Michalski said.

“The life would have originated in these hydrothermal settings and survived in the underground for quite a long time,” he said.

And as the Earth’s deep biosphere is an indication, the underground Martian microbial communities could be exceptionally rich and diverse. The earth’s deep biosphere was first discovered only about 30 years ago, and estimates since then have suggested that the deep-living micro-organisms constitute almost half of all life on the planet, Michalski told Live Science.

Microbes in the Earth’s deep biosphere play a role in the burial of carbon that could otherwise be a greenhouse gas, are associated with deep energy resources “and are important for understanding the origin and evolution of life,” Michalski said.

“We are at a point now where it is really a boundary of understanding of what ‘deep biosphere’ really means on Earth, and how that relates to exo-planets and the other planets in our solar system,” he said. “It is a window to our own origin.”

Mars surface, is a particularly promising place to start looking for alien microbes because it is “more habitable” for micro-organisms than the Earth’s deep biosphere. Underground rock on Mars is more porous than it is on Earth — making bags for the nutrients and gas exchange, and Mars’ cooler core (while still molten) provides a more welcoming temperature for microbes living in deep rock, Michalski added.

“We can single-celled organisms that can be dormant for a long time, but can survive by metabolizing hydrogen, methane, and possibly sulphur,” Michalski told Live Science. “Without being too specific, we think that there are a lot of possibilities.”

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Original article on Live Science.

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