Italian scientists say they have discovered a lake of liquid water beneath the southern polar ice cap of Mars.
The finding was reported in the journal Science on Wednesday and is the result of radar echoes picked up by an instrument on a spacecraft that has been orbiting the red planet for 15 years.
The pool is said to be about 20 kilometers wide and no more than a meter deep.
Researchers noted that the lake's ice-cold temperatures and high levels of salt create a harsh environment for any living organism.
But they didn't rule out the possibility of life.
In order to find out, scientists will have to send a robot that is able to drill through the thick layer of ice that is encapsulating the lake.