Mars study reveals subsurface water in Red Planet’s vast lake system

Researchers working with data from the European Space Agency’s Mars Express orbiter have detected four subsurface lakes at the planet’s south pole. In a follow up to the 2018 discovery of a large body of water about 1.5 kilometers beneath the surface, three more water bodies were found in the same region spanning about 75,000 square kilometers.

“We identified the same body of water, but we also found three other bodies of water around the main one,” planetary scientist Elena Pettinelli of the University of Rome, one of the scientists responsible for the discovery, said in comments published by the journal Nature. “It’s a complex system.” The full data findings were detailed in a paper published on September 28th.

The Martian lakes were found using an instrument called the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) which measures with radio waves similar to how subsurface glacial lakes on Earth are identified. Given both the depth and the freezing temperatures on the planet, it’s also thought that the subsurface water must have a high salt content similar to some Antarctic regions. “From a thermal point of view, it has to be salty,” Pettinelli said.

Mars topography map with false-color additions. | Image credit: NASA/JPL

Where water is found, the potential for also finding life is increased substantially, and salt levels up to five times that of Earth’s ocean water have been found to be amenable to life on our planet. NASA’s Perseverance rover, currently on its way to the red planet, will be searching for those very indicators with its astrobiologically-focused mission. At the super salt concentrations that might be required for liquid water on Mars, though, the environment is more problematic if not impossible.

“There’s not much active life in these briny pools in Antarctica,” John Priscu, an environmental scientist at Montana State University explained. “They’re just pickled. And that might be the case [on Mars].” Priscu’s group in Bozeman studies microbiology in icy environments, and in water where salt concentrations reach around 20 times ocean water levels, life is absent.

Another issue with the recent Mars Express data may be what the findings indicate overall, namely whether the ‘bright spots’ identified as possible lakes are actually lakes at all. There has been debate among scientists since the original 2018 discovery over whether Mars’s core emits enough heat to support liquid lakes, for instance.

“I do not think there are lakes,” Jack Holt, a planetary scientist at the University of Arizona, countered. “There is not enough heat flow to support a brine here, even under the ice cap.” Holt is on one of the science teams of NASA’s Mars Reconnaissance Orbiter. “If the bright material really is liquid water, I think it’s more likely to represent some sort of slush or sludge,” concurred Mike Sori, a planetary geophysicist at Purdue University.

Still, regardless of the outcome, the findings add to the growing dataset for future Mars-bound travelers to use in their exploration plans. But if these subsurface lake findings are further confirmed in the near future, the search for life on Mars just became a bit more promising.

Mars study reveals subsurface water in Red Planet’s vast lake system
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