8 Things You Need To Know About NASA Finding Water On Mars
7. So Are They Streams?
Even though they contain flows of liquid water, the RSL are not exactly the picturesque, babbling brooks that you might be envisioning.
Pure liquid water is highly unstable on the surface of Mars due to the lower atmospheric pressure. Basically, water on Mars boils and becomes a gas at 10°C, but it still freezes at the usual 0°C, leaving only a narrow window in which liquid freshwater can exist.
Fortunately, this is where perchlorates come into it. These chlorinated hydrocarbons can basically bind water to them and prevent it freezing or evaporating when it usually would. This creates a super-concentrated brine and this is what is supposedly flowing down the Martian slopes. Maybe a way to think of them is like those expanding water gel beads that people use in flower arranging.
On Earth, some microbes actually use perchlorates as part of their life cycle, using it as an energy source. So, even though these RSL are less like the lush, verdant rivers as much as a sort of super-salty ooze (yum), life still isn't off the cards.