In 2018 scientists reported the discovery of a large saltwater lake under the ice at Mars’s south pole. The researchers have confirmed the presence of that lake and now found three more lakes.
The discovery was reported on September 28 in Nature Astronomy, using radar data from the European Space Agency’s Mars-orbiting spacecraft, called Mars Express following the detection of a single subsurface lake in the same region on the discovery in 2018. The finding was based on just 29 observations made from 2012 to 2015 and researchers said that they need more evidence to support the claim.
Mars Express used a radar instrument called the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS). It sends out radio waves that bounce off layers to the planet’s surface and subsurface. The signal is reflected to indicate the kind of material that is present at a location like rock, ice, or water. The team detected areas that indicate bodies of liquid water trapped more than one kilometer of Martian ice.
The low pressure that results from the planet’s lack of a substantial atmosphere makes liquid water impossible. Mars must have a high salt content to make water remain liquid. There could be water trapped under Mars’s surface, when the planet once had seas and lakes billions of years ago.
The presence of the lakes is still debated. Researchers were not convinced that the identified regions were water. But if such exist it could be potential habitats for Martian life.