Mars is hiding a lake -- and new hope for (tiny) Martian life

Microbes on Earth have been known to survive in similar conditions.

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Eric Mack
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Here is an illustration of the Mars Express spacecraft probing the southern hemisphere of Mars. 

ESA/INAF/Davide Coero Borga

Mars may look dusty and dead, but scientists have uncovered strong evidence of a lake of liquid water lying beneath the Red Planet's southern ice cap. 

For centuries, there have been hints and hopeful speculation of a wetter side of Mars, from alien-built canals to dark streaks that kinda, sorta look like damp sand. But time and again, further investigation reveals that any potential water spotted on our neighbor world is either an illusion or frozen stiff

A team of researchers used radar data collected from the European Mars Express orbiter to identify what appears to be a salt water lake 20 kilometers (12.5 miles) wide and about 1.5 km (1 mile) below the surface of the ice.

The investigation took several years to rule out other possible explanations for the radar echoes picked up at the bottom of Mars.

"We found, in fact, that any other explanation for these very strong echoes was not really tenable," said Roberto Orosei of the Italian National Institute for Astrophysics, who is lead author on a paper published online Wednesday in the journal Science. "So we had to conclude that there is water on Mars today."

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Orosei said in a video released by Science that the team was unable to determine how deep the subglacial lake might be, but he estimates that it extends at least one meter.

"Which is something that really qualifies this as a body of water, a lake. [It's] not really like some kind of melt water filling some space between rock and ice." 

Finding water doesn't mean that we've found a weird warm spot at the Martian south pole, however. Orosei estimates the hidden lake could be as cold as -30 degrees Celsius (-22 degrees F), but fails to freeze because of the high salt content that significantly lowers its freezing point. Similar super-chilled lakes exist on Earth beneath the Antarctic and Greenland ice sheets. 

What about the inevitable follow-up question about alien life forms swimming around?

"This is certainly not a very pleasant environment for life," Orosei said, but noted that there are single-celled organisms on Earth that can survive in very cold briny waters by feeding on those salts.

It won't be easy to confirm that what looks like a lake on radar isn't just another false start in the search for a moist part of Mars. The research will likely require sending a robot with a serious drilling rig. That's probably beyond our technological capability for now, although Elon Musk and his Boring Company may beg to differ

That said, the paper in Science ends on a hopeful note: "There is no reason to conclude that the presence of subsurface water on Mars is limited to a single location."

So the search for an oasis on Mars continues. If found, it'll likely appeal only to fans of intensely salty drinks. Martian margaritas, anyone?

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