A team of scientists studying data from a satellite orbiting Mars say they have discovered evidence of several lakes of what they believe is salty, liquid water beneath the surface of the planet's south pole.
The discovery, detailed in a study published Monday in the journal Nature Astronomy, expands upon a tentative finding in 2018, which was made using data from the European Space Agency's (ESA) Mars Express satellite.
A radar instrument known as the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) produced evidence of what astronomers believed was a large saltwater lake under the ice at Mars's south pole, a finding that was met with excitement and some skepticism at the time.
Since then, the same group of scientists examined 10 years' worth of radar images sent from the spacecraft and found not only more evidence confirming the original salt lake, but enough for at least three more lying underneath the Martian surface.
Confirming the existence of liquid water on Mars is significant, in that it could provide a possible habitat for life.
The new evidence came after researchers examined over 100 radar images taken by the satellite from 2010 through 2019. The scientists saw what seemed to be several subglacial liquid bodies ranging in size from just over 19 kilometers across to as small as just under 5 kilometers.
The average temperature on Mars is around minus 26 degrees Celsius, far too cold for water to remain liquid at the surface. But the researchers believe the lakes maintain their liquid state due to their high concentrations of salt.
Some scientists believe Mars was once a wet, warm world and may even have hosted life forms at some point in its early history. But over time, the planet's atmosphere was stripped away because it lacks a magnetic field like Earth's, making it seemingly inhospitable.
This latest discovery suggests that some pockets of the Martian terrain may be habitable and could contain some form of microbial life that escaped from the planet's freezing surface to the waters beneath.