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Mars subsurface holds potential for microbial life, study suggests

The Perseverance rover is currently heading across Mars to search for evidence that there was once microbial life living there. Now, new research suggests that the area beneath the planet’s surface, called the subsurface, might be potentially hospitable for life.

Even though much of life as we know it relies directly or indirectly on sunlight, there are environments in which life can flourish even without sunlight. On our planet, these ecosystems can be found in deep caves or at the bottom of the ocean around thermal vents. Researchers believe that the Martian subsurface could be similarly habitable for microorganisms.

This is similar to a phenomenon found on Earth, where bacteria can survive underground without sunlight thanks to chemical reactions between rocks and water such as radiolysis where radioactive elements react with water to produce hydrogen and oxygen.

To understand what the Martian subsurface is made of, researchers can look at meteorites that have landed on Earth from Mars and analyze their composition. The researchers in the new study found evidence of radioactive elements in Mars meteorites, as well as rocks with large enough pores to trap water.  That means there is evidence that subsurface rocks could provide a home for bacteria if they were in contact with water.

“The big implication here for subsurface exploration science is that wherever you have groundwater on Mars, there’s a good chance that you have enough chemical energy to support subsurface microbial life,” said lead author of the study Jesse Tarnas, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory and Brown University, in a statement. “We don’t know whether life ever got started beneath the surface of Mars, but if it did, we think there would be ample energy there to sustain it right up to today.”

This opens up a new opportunity for research in the search for life, by digging down beneath the Mars surface.

“The subsurface is one of the frontiers in Mars exploration,” Brown University professor Jack Mustard said. “We’ve investigated the atmosphere, mapped the surface with different wavelengths of light, and landed on the surface in half-a-dozen places, and that work continues to tell us so much about the planet’s past. But if we want to think about the possibility of present-day life, the subsurface is absolutely going to be where the action is.”

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