Beneath the Frost: Discovery of a Hidden Lake on Mars

A group of Italian researchers claims to possess compelling proof of a hidden lake of liquid water on Mars. This finding contributes to the conjecture that life may have existed on Mars in the past — and enhances the idea that it could potentially exist there even now, given that liquid water is a vital component for life.

The evidence stems from a device known as MARSIS, which is part of the European Space Agency’s Mars Express satellite orbiting the Red Planet. MARSIS is a specific type of radar referred to as ground-penetrating radar.

“Ground-penetrating radars utilize radio waves that can penetrate the soil and subsequently return reflections from the material beneath the surface,” explains Roberto Orosei, lead researcher on MARSIS and a planetary scientist at the Italian National Institute for Astrophysics.

Such radars are advantageous when investigating potential liquid water sources, “because water serves as a very potent radar reflector,” he notes.

Between May 2012 and December 2015, the Mars Express radar mapped a region adjacent to the south pole of Mars.

Upon examining the data, Orosei and his team discovered what appeared to be a lake measuring approximately 12 miles in diameter, lying a mile beneath a surface composed of water ice and dust. Scores of these subglacial lakes exist on Earth, primarily in Antarctica.

However, Orosei and his colleagues were cautious about declaring they had found liquid water on Mars. Extraordinary claims that seem implausible often turn out to be so.

Instead, they endeavored to devise as many alternative explanations as possible for their observations.

“After years—literally a couple of years of … discussions, debates, and let’s say, mutual puzzlement,” Orosei states, “we genuinely began to feel assured that any other explanation would be inadequate.”

Or, he adds, somewhat paraphrasing Sherlock Holmes, “When you have eliminated the impossible, whatever remains must necessarily be the truth.”

A report detailing the discovery of the subterranean lake appears in the journal Science.

Other researchers are very impressed.

“I believe this is exceptionally strong evidence that liquid water exists beneath the poles in this south polar layered terrain on Mars, which is tremendously thrilling,” remarks Ellen Stofan, the John and Adrienne Mars Director at the Smithsonian’s National Air and Space Museum. Prior to her tenure at the museum, she was part of the MARSIS science team.

Stofan notes that finding liquid water is something scientists are extremely keen on, “because life here on Earth developed in liquid water. It persisted in the oceans for over a billion years. Therefore, as we extend our search beyond Earth, seeking signs of life elsewhere, we are consistently on the lookout for liquid water.”

The water in the Martian subterranean lake is likely salty; otherwise, it would solidify even deep underground, Stofan explains. Furthermore, the salts are probably composed of substances known as perchlorates, “which are highly toxic to life here on Earth. But on Mars, who can say?”

The origin of the water discovered by the Italian team remains unclear, and it is uncertain whether other underground lakes can be found.

Nevertheless, it is certain that these new findings will motivate other scientists to explore further.

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