Ancient underground lakes discovered on Mars

Mars could be home to more liquid water than we originally thought.

Amanda Kooser
Freelance writer Amanda C. Kooser covers gadgets and tech news with a twist for CNET. When not wallowing in weird gear and iPad apps for cats, she can be found tinkering with her 1956 DeSoto.
Amanda Kooser
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This beautiful ESA image of the Martian surface is titled Cappuccino swirls at Mars' south pole.

ESA/DLR/FU Berlin/Bill Dunford

Be sure to pack arm floaties and a really big drill when you visit Mars. A whole world of water-filled ponds may be hiding beneath the southern ice cap on the dry and dusty red planet.

A new study led by researchers at Roma Tre University in Italy strengthens the case for a 2018 discovery of a hidden lake under the Martian polar ice, and then extends the find to include three new ponds. 

The researchers used radar data from the European Space Agency's Mars Express orbiter to make its original detection of liquid water. 

"Now, taking into account more data and analyzing it in a different way, three new ponds have been discovered," ESA said in a statement Monday. The team published its study in the journal Nature Astronomy on Monday.

The lakes appear to be lurking under a hefty layer of ice. The largest lake is about 19 miles (30 kilometers) across with a series of smaller ponds surrounding it. 

The researchers expect the water must be incredibly salty to stay liquid at low temperatures. A separate 2019 study suggested volcanic activity might help keep the water from freezing, but the current paper leans heavily into the salt concept.

"While it is not possible for water to remain stable on the surface today the new result opens the possibility that an entire system of ancient lakes might exist underground, perhaps millions or even billions of years old," said ESA.

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Humans are busy searching for signs of life -- particularly evidence of ancient microbes -- on Mars. NASA's new Perseverance rover will continue this quest from the surface of the red planet. Liquid water reservoirs would be an especially tempting place to look for life, but reaching these ponds would be extremely difficult. There's 1 mile (1.5 kilometer) of ice in the way.

We may not get any big answers out of the Martian south pole anytime soon, but it could give us a future target for exploration once our technology is up to the challenge.