Dark, finger-like features that appear and extend down some Martian slopes during the warmest months of the Mars year may be evidence of salty water on Mars.
These features in Mars’s southern hemisphere can best be explained by flows of briny water, although competing theories have also been proposed.
If the geographical features are in fact due to salty water, it will be the first observation of liquid water on Mars.
Read more at Jet Propulsion Laboratory, California Institute of Technology