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Briny Underground Lakes May Be All That Remain of Martian Ocean | Smart News

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When scientists first found signs of a lake under Mars’ south pole in 2018, questions abounded over how such a feature could form and whether the measurements were accurate. Now, a study published this week in Nature Astronomy not only confirms the size and location of the first lake, but also shows three more, smaller bodies of water nearby.

The study adds 100 measurements to the team’s original 29 figures for a clearer picture of the region. The four lakes are hidden a mile under the surface of Mars’ icy south pole, and may be full of salt and sediments to remain liquid even in extreme cold temperatures. Some scientists not involved in the study are cautious about the research team’s conclusions, but the study authors see the discovery as an optimistic signal in the search for life on Mars.

“Here we have not just an occasional body of water, but a system,” Roma Tre University planetary scientist Elena Pettinelli, a co-author on the study, tells Nadia Drake at National Geographic. “The system was probably existing a long time ago, when the planet was very different, and this is maybe the remnant of that.”

Even if the lakes are inhospitable for life, the fact that the south pole holds multiple water features suggests that they might be the last remnants of the Red Planet’s ancient oceans. Mars is covered in the signs of erosion that suggest water once flowed across its now dry, rocky surface. Observations made by the Curiosity rover suggest that Mars used to be covered in a vast ocean, Colin Schultz wrote for Smithsonian in 2013.

“As the early Martian climate cooled, such an ocean would have frozen and eventually sublimed away,” or evaporated from solid ice into water vapor without melting first, Planetary Science Institute researcher

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There might be even more underground reservoirs of liquid water on Mars

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Four underground reservoirs of water may be sitting below the south pole of Mars. The new findings, published today in Nature Astronomy, suggest Mars is home to even more deposits of liquid water than once thought.

The background: In 2018, a group of Italian researchers used radar observations made by the European Space Agency’s Mars Express orbiter to detect a lake of liquid water sitting 1.5 kilometers below the surface of Mars. The lake, which was about 20 kilometers long, was found near the south pole, at the base of an area of thick glacial ice called the South Polar Layered Deposits. Those radar observations were made by an instrument called Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS).

The new study: Two years later, after a new analysis of the complete MARSIS data set (composing over 134 radar collection campaigns), members of that same team have confirmed the presence of that body of water. But they have also found evidence of three others, each less than 50 kilometers away from the location of the first. The new analysis applies lessons learned in discriminating between wet and dry subglacial conditions in radar data for Antarctica and Greenland. 

The newly discovered patches of water don’t seem to be much different from the one found in 2018. They range from an estimated 10 to 30 kilometers in length. They all start at a depth of about 1.5 kilometers underground, although it’s still unknown how deep any of them actually run.

The water: Don’t expect to be able to drink this water. The only reason it’s been able to stay liquid despite frigid temperatures on Mars is that it’s likely very briny (or salty). Salts can significantly lower the freezing point of water. Calcium, magnesium, sodium, and other salt deposits are found