Researchers in Italy have announced what they hope is a major discovery: A body of salty water may lurk beneath the surface of Mars, just off to the side of one of the red planet’s massive ice caps.
In a paper published (paywall) in the journal Science, the team reports using electromagnetic radar on the European Space Agency’s Mars Express spacecraft to probe a region on the southern pole of Mars. The radar, known as Mars Advanced Radar for Subsurface and Ionosphere Sounding, or MARSIS, echoed back more over an area of 12 miles (20 km), as Gizmodo explains. Between 2012 and 2015, researchers carefully measured these reflections. After ruling out all other possible explanations, they concluded that this 12-mile stretch must be some sort of underground reservoir of liquid water, at least three feet (about 100 cm) deep.
Water here would be a tantalizing sign of possible life—although there’s still no evidence of anything living on Mars. “This could be, perhaps, the first habitat we find on Mars,” Roberto Orosei, a planetary scientist at the National Institute of Astrophysics in Italy and lead author of the paper, told the Washington Post (paywall).
The idea that there could be water in these specific regions was put forward some 30 years ago by Stephen Clifford, a scientist who now works at the Planetary Science Institute in Tucson, Arizona. Water on Mars has previously been found either frozen, or in ancient remains. The water in this particular case is thought to be mixed with perchlorate salts, which would make it thick (and poisonous to humans)—and explain how it can exist in liquid form at temperatures around -90°F (-67.7°C).
The possibility of water is the most recent hint that some kind of life could inhabit Mars. Scientists will next likely look for connecting bodies of water to see if they have found a lone reservoir or part of a larger labyrinth of underground water. Water more abundant than perviously thought could be a resource for future astronauts (provided it can be filtered and heated properly).
These findings still need to be confirmed—ideally by an actual visit to the planet. However, at the moment, the world’s space powers are actually forbidden to actually get near any Martian water, per the 1967 Outer Space Treaty, out of concerns for contaminating any life that may be there with bits of our own.