Three underground lakes have been detected close to the south pole of Mars.
Scientists additionally confirmed the existence of a fourth lake – the presence of which was hinted at in 2018.
Liquid water is significant for biology, so the discovering might be of curiosity to researchers finding out the potential for all times elsewhere within the Solar System.
But the lakes are additionally regarded as extraordinarily salty, which might make it tough for any microbial life to outlive in them.
Mars’ skinny ambiance signifies that the presence of liquid water on the floor is a near-impossibility. But water might stay liquid beneath floor.
The newest discovery was made utilizing information from a radar instrument on the European Space Agency’s (Esa) Mars Express spacecraft, which has been orbiting the Red Planet since December 2003.
In 2018, researchers used information from the Marsis radar to report indicators of a 20km-wide subsurface lake positioned 1.5km beneath Mars’ south polar layered deposits, a thick polar cap shaped by layers of ice and dirt.
However, that discovering was primarily based on 29 observations collected by Marsis between 2012 and 2015. Now, a group together with most of the identical scientists from the 2018 research have analysed a a lot greater dataset of 134 radar profiles gathered between 2010 and 2019.
“Not only did we confirm the position, extent and strength of the reflector from our 2018 study, but we found three new bright areas,” mentioned co-author Elena Pettinelli from Roma Tre University in Italy.
“The main lake is surrounded by smaller bodies of liquid water, but because of the technical characteristics of the radar, and of its distance from the Martian surface, we cannot conclusively determine whether they are interconnected.”
The group borrowed a method generally utilized in radar sounder investigations of sub-glacial lakes in Antarctica, Canada and Greenland, adapting the strategy to analyse the information from Marsis.
“The interpretation that best reconciles all the available evidence is that the high intensity reflections (from Mars) are coming from extended pools of liquid water,” mentioned co-author Sebastian Lauro, additionally from Roma Tre University.
There’s not sufficient warmth at these depths to soften the ice, so scientists imagine the liquid water should include excessive concentrations of dissolved salts. These chemical salts (totally different to the stuff we sprinkle on our chips) can considerably decrease water’s freezing level.
In truth, latest experiments have proven that water with dissolved salts of magnesium and calcium perchlorate (a chemical compound containing chlorine certain to 4 oxygens) can stay liquid at temperatures of -123C.
“These experiments have demonstrated that brines can persist for geologically significant periods of time even at the temperatures typical of the Martian polar regions (considerably below the freezing temperature of pure water),” mentioned co-author Graziella Caprarelli, from the University of Southern Queensland, Australia.
“Therefore we think that any process of formation and persistence of sub-ice water beneath the ice polar caps requires the liquid to have high salinity.”
Whether life might survive in such circumstances will depend on simply how salty these Martian swimming pools are. On Earth, solely very particular forms of microbes, often known as halophiles, can survive within the saltiest our bodies of water.
Roberto Orosei, chief scientist on the Marsis experiment, mentioned: “While the existence of a single sub-glacial lake could be attributed to exceptional conditions such as the presence of a volcano under the ice sheet, the discovery of an entire system of lakes implies that their formation process is relatively simple and common, and that these lakes have probably existed for much of Mars’ history.
“For this purpose, they might nonetheless retain traces of any life types that might have advanced when Mars had a dense ambiance, a milder local weather and the presence of liquid water on the floor, just like the early Earth.”