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