Although the first study suggesting liquid water might be found at the base of Martian polar caps was published almost 31 years ago, the new findings mark the first tangible evidence of the presence of liquid water on the Red Planet.
Deep dive from the sky The discovery was led by a team of Italian researchers who used the readings sent back by the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS).
Analysing the properties of the reflected radar signals and considering the composition of the layered deposits and expected temperature profile below the surface, the scientists interpret the bright feature as an interface between the ice and a stable body of liquid water, which could be laden with salty, saturated sediments. This is the first time that they've found a sustained body of water on the planet.
If confirmed, this would be the most significant body of liquid water found on Mars to date. They focused on a region below the surface of Mars' southern polar ice cap, an area suspected for the past 31 years to have an underground lake. On Earth, places like these are home to bacteria adapted to the extreme conditions of sub-glacial, briny lakes. (AAP) A provided image shows an artist's impression of the Mars Express spacecraft probing the southern hemisphere of the red planet. However, "SHARAD uses higher-frequency radio waves that cannot penetrate as deep as MARSIS can", Pettinelli says. But scientists thought that Mars had lost the majority of its liquid water.
What does discovery of liquid water on Mars actually mean?
Water is usually a sign of life, in fact, it's one of the principles of astrobiology. The ice on Mars would also shield the Martian lake from the damaging radiation that bombards the planet's surface.
Several researchers said it would be crucial to figure out whether this body of water is the only one, or part of an interconnecting body of underground aquifers - in part because a network increases the possibility it could have harboured life.
"This is now our best, albeit slim chance of discovering life elsewhere in our Solar System until the more complex missions to Europa or Enceladus, the moons of Jupiter and Saturn we also believe have subterranean water sources". "Moreover, it provides a valuable confirmation that the water that once flowed abundantly over the Martian surface in the form of seas, lakes and rivers filled the voids in the subsurface". But the radar reflections could be produced by a layer of water less than a meter thick, so it could be just a thin layer of liquid lining the base of the ice sheet.
Michael Meyer believes the more we study Mars, the more we will learn how life could be supported and where there are resources to support life in the future.
However, its radar technology varies slightly from the one onboard the Mars Express.
The scientists who analyzed these radar echoes were careful to consider all the things that could have made the echoes they measured, including explanations that don't involve liquid water, and they were able to rule out most of those explanations.
Now that we know for sure that there is a reservoir of liquid water just beneath the planet's surface, astronomers around the globe will be thinking of ways to get down to that water to see what's there.