Scientists are celebrating Christmas in July after discovering Mars has a pool.
A radar-equipped probe has detected the first concrete evidence of existing liquid water on Mars, in the form of a large lake under one of its polar ice caps.
Lead researcher Roberto Orosei said it’s the closest his team can get to confirming that the lake is truly water, without drilling through a glacier to sample the reservoir.
“We discovered water on Mars,” Orosei said, in a video interview released with the study.
The discovery resolves a long-running debate over whether there is liquid water on Mars, according to the Italian Space Agency (ASI) researchers who ran the operation.
The lake is approximately 20 kilometres wide and sits 1.5 km below the Martian surface under a heavy polar glacier. It’s also extremely cold and filled with a briny mix of salt and other minerals, according to the study published in the latest edition of the journal Science.
WATCH: Italian Space Agency says concrete evidence found of liquid water on Mars
The buried lake was first detected by a team of Italian astronomers using the Mars Express spacecraft, which surveyed the planet’s southern polar cap between May 2012 and December 2015.
The spacecraft used a ground-penetrating radar to scan the region and found a sharp contrast in the echo under a section of the glacier, which matched the profile of a subglacial lake.
The research team spent several years taking more scans and analyzing the data before announcing the findings to confirm the data.
“Any other explanation for these very strong echoes was not really tenable,” Orosei said.
“We had to conclude that there is water on Mars today.”
The suspected lake matches the radar profile of the liquid water reservoirs under glaciers in Antarctica and Greenland, according to the study.
The results appear to be scientifically sound, and reflect the same kind of scans that are produced by subglacial lakes on Earth, according to Anja Diez of the Norwegian Polar Institute.
“They rule out a number of possible explanations … leaving the existence of liquid water, either as a distinct water layer or as saturated sediments, as the only explanation,” she wrote in a commentary on the findings.
Worst lake ever
The prospect of water on Mars is enough to spark renewed talk of one day colonizing the Red Planet.
However, the underground reservoir isn’t exactly human friendly.
“This is certainly not a very pleasant environment for life,” Orosei said.
Orosei didn’t rule out the possibility of life altogether, as there are single-cell organisms that live in similar subglacial lakes on Earth.
He estimates the water temperature to be somewhere between -10 and -30 C, though it’s probably still liquid because of dissolved salt, magnesium, calcium and sodium that would have leached into it from the Martian rock.
“Together with the pressure of the overlying ice, this lowers the melting point, allowing the lake to remain liquid,” the study authors say.
Orosei says the water is at least one metre deep, although scans are unable to determine exactly how deep it goes.
The lake sits under a glacier on the southern plain of Mars, known as the Planum Australe.
The lake was found in a relatively flat area where ground-penetrating radar scans are easier to read, ASI scientist Enrico Flamini told Global News.
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Flamini has been looking for water on Mars since the 1970s, and was among the scientists who pushed for a radar to be installed on the Mars Express in the first place.
He says he suspected there might still be underground water on Mars, based on the knowledge that it once flowed across the surface.
“This water could have also penetrated to the subsurface,” he said. “If this was the case, water should have remained there.”
Flamini says the suspected lake has likely been there since Mars had liquid water, some four billion years ago. And if that’s the case, it might also contain microscopic life left over from that period.
He added that his team has now developed a process for finding underground water, which should make it easier to find more lakes under the Martian surface.
The Mars Express first detected frozen water within the polar glacier in 2004. However, most of the ice is composed of frozen carbon dioxide.
Orosei says another mission is necessary to determine for sure whether there is water beneath the glacier. However, that would require more advanced technology than is currently available, because the lander would need to drill 1.5 kilometres down in order to reach the suspected lake.
“Getting there and acquiring the final evidence that it is indeed a lake will not be easy,” he said.
Flamini says it’s also not a great spot for a human colony, because they would also need to dig deeply to access the potential water supply.
“Let’s search for something that is maybe nearer to the surface,” he said.
Flamini says the next best opportunity to look for water will likely come with the launch of the Mars 2020 rover, which is slated to carry a wide array of instruments to the Red Planet.
“Now it’s time for other teams to work on this,” he said.