There have been small indications of water on Mars before, but the researchers say this is the first evidence of stable bodies of water. But there’s little heat flowing from the geologically dead interior of Mars, and under the planet’s weak gravity, the weight of 1.5 kilometers of ice does not lower the melting point by much.
The readings turned up evidence of a particularly bright radar reflection in a 12-mile-wide (20-kilometer-wide) area. The discovery was reported in the journal Science.
Researchers have long debated over whether Mars contains liquid water, a question that has finally (for the most part) been settled.
Jonathan Lunine, director of the Center for Astrophysics and Planetary Science at Cornell University, who was not involved with the research, said the finding transforms Mars from a dusty planet to yet another “ocean world” in the solar system. It was already there or thereabouts – Jupiter’s moon Europa and Saturn’s moon Enceladus have both been shown to have large bodies of water, and another Saturnian moon, Titan, is known to have standing bodies of liquid methane, but Mars was always a likely candidate, because of the evidence that large bodies existed in the past. It was home to plenty of liquid water and lakes at least 3.6 billion years ago. “Those are not ideal conditions for life to form”, Siebach said.
A new mission to Mars may have to wait, though. “This really qualifies this as a body of water”. But, he cautions, “I’d say it’s not quite the smoking gun”.
Indeed, scientists have found bacteria and other simple forms of life living in these kinds of extreme environments on our own planet, which use chemical reactions with salts and minerals to get the energy they need to live.
Given its location beneath the polar ice cap, the water is expected to be below the freezing point of water. However, there are [analogous organisms] on Earth, in the subglacial lakes of Antarctica. Orbiters have also revealed huge glaciers residing just under the surface, potentially accessible to any future explorers or even colonists that go there in the future. Although if it is, biologists have said that it would be at the limits of habitability. The Mars water would have to have a similar make-up to actually be liquid. For water to remain liquid at those temperatures, it would have to be incredibly briny. In 1987, the astronomer Stephen M. Clifford theorized that liquid water might be hiding, deep below the planet’s polar ice caps. That suggests that the water is brim full of salts, allowing it to melt. But in the two decades he’s spent studying it, he hasn’t been able to coax life from it.
“But there are terrestrial organisms that can survive and thrive, in fact, in similar environments”. MARSIS sends electromagnetic pulses down to the planet and measures how they echo back – and Orosei and colleagues discovered especially bright reflections from a broad region spanning about 12 miles, about a mile below the ice.
Between May 2012 and December 2015, Dr. Cicchetti and colleagues used MARSIS to survey a region called Planum Australe, located in the southern ice cap of Mars.