As NASA’s Perseverance rover begins its search for ancient life on the surface of Mars, a new study suggests the Martian subsoil may be a good place to search for possible current life on the Red Planet.
The study, published in the journal Astrobiology, examined the chemical makeup of Martian meteorites – rocks lifted off the surface of Mars that eventually landed on Earth. Analysis determined that these rocks, if in constant contact with water, would produce the chemical energy needed to support microbial communities similar to those that survive in the unlit depths of the Earth. Because these meteorites may be representative of large swathes of the Martian crust, the results suggest that much of Mars’ subsoil could be habitable.
“The big implication here for the science of underground exploration is that wherever you have groundwater on Mars, there’s a good chance that you have enough chemical energy to support microbial life underground,” Jesse said. Tarnas, a postdoctoral researcher at NASA’s Jet Propulsion Laboratory who led the study while completing his doctorate. at Brown University. “We don’t know if life ever began below the surface of Mars, but if it did, we believe there would be enough energy to sustain it until today.”
Over the past few decades, scientists have discovered that the depths of the Earth are home to a vast biome that exists largely separate from the world above. Lacking sunlight, these creatures survive using the byproducts of chemical reactions produced when rocks come into contact with water.
One of these reactions is radiolysis, which occurs when radioactive elements in rocks react with water trapped in the pores and fracture space. The reaction breaks water molecules into their building blocks, hydrogen and oxygen. The released hydrogen is dissolved in the remaining groundwater, while minerals like pyrite (madman’s gold) absorb free oxygen to form sulphated minerals. Microbes can ingest dissolved hydrogen as fuel and use the oxygen stored in sulfates to “burn” that fuel.
In places like the Kidd Creek mine in Canada, these “sulfate reducing” microbes have been found living more than a mile underground, in water that has not seen the light for over a billion years. years. Tarnas is working with a team co-led by Professor Jack Mustard of Brown University and Professor Barbara Sherwood Lollar of the University of Toronto to better understand these subterranean systems, with the goal of looking for similar habitats on Mars and elsewhere in the system. solar. The project, titled Earth 4-D: Subsurface Science and Exploration, is funded by the Canadian Institute for Advances in Research.
For this new study, the researchers wanted to see if the ingredients for radiolysis-focused habitats could exist on Mars. They drew on data from NASA’s Curiosity rover and other orbiting spacecraft, as well as compositional data from a suite of Martian meteorites, which are representative of different parts of the Earth’s crust.
Researchers were looking for the ingredients of radiolysis: radioactive elements like thorium, uranium and potassium; sulphide minerals which could be converted to sulphate; and rock units with adequate pore space to trap water. The study found that in several different types of Martian meteorites, all of the ingredients are present in sufficient abundance to support Earth-like habitats. This was especially true for the breccias of regoliths – meteorites from crustal rocks more than 3.6 billion years old – which had the highest survival potential. Unlike Earth, Mars does not have a plate tectonics system that constantly recycles crustal rocks. So these ancient grounds remain largely intact.
The researchers say the findings help argue for an exploration program that looks for signs of current life in the Martian subsoil. Previous research has found evidence of an active groundwater system on Mars in the past, researchers say, and there is reason to believe groundwater exists today. A recent study, for example, raised the possibility that an underground lake is hiding under the southern ice cap of the planet. This new research suggests that wherever there is groundwater, there is energy for life.
Tarnas and Mustard say that while there are certainly some technical challenges involved in underground exploration, they are not as overwhelming as people might think. A drilling operation would not require “an oil rig the size of Texas,” Mustard said, and recent advances in small borehole probes could soon put Martian depths within reach.
“The subsoil is one of the frontiers of Mars exploration,” Mustard said. “We’ve studied the atmosphere, mapped the surface with different wavelengths of light, and landed on the surface in half a dozen places, and this work continues to tell us a lot about the planet’s past. the possibility of current life, the basement will be absolutely where the action is. “
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