Three underground lakes have been detected near the south pole of Mars.
Scientists also confirmed the existence of a fourth lake – the presence of which was hinted at in 2018.
Liquid water is vital for biology, so the finding will be of interest to researchers studying the potential for life elsewhere in the Solar System.
But the lakes are extremely salty, which could make it difficult for any microbial life to survive in them.
Mars’ thin atmosphere means that the presence of liquid water on the surface is a near-impossibility. But water could remain liquid below ground.
The latest discovery was made using data from a radar instrument on the European Space Agency’s (Esa) Mars Express spacecraft, which has been orbiting the Red Planet since December 2003.
