NASA's Curiosity rover has discovered critical evidence that there may be water under Mars' surface.
Deposits of ice have already been found on Mars, but these findings suggest this ice could be turned into liquid water, which is a key element for the existence of life.
According to the Washington Post, Curiosity was exploring the Red Planet's Gale Crater when it came upon salts known as perchlorates.
Under the right temperatures and humidity, perchlorates can drastically lower the temperature of ice and absorb water vapor from the atmosphere, turning it into a salty solution.
Morten Bo Madsen, associate professor and head of the Mars Group at the University of Copenhagen, said of perchlorates:
These can decrease the freezing point of water by more than 70 degrees. And they attract water quite violently.
Curiosity's weather technology discovered such conditions exist every day during Mars' winter and spring seasons.
Overnight, the ice on Mars may be converted into liquid water, which then soaks into its soil, the Guardian reports.
The planet Mars once contained an entire ocean, but the Gale Crater currently is too cold to support microorganisms.
Bo Madsen and his fellow study authors, however, are under the impression perchlorates aren't just confined to this area, so the conversion of ice into liquid water may be occurring all over Mars.
But even if water were to form, it would be in quantities small enough to fit in-between grains of soil.
There's so little water that you can't even see it visibly.
Mars' surface is also penetrated deeply by cosmic radiation that has proven to be able to kill Earth's most durable microorganisms.
If there was ever life on Mars, it most likely existed billions of years ago when scientists say the planet was protected from this radiation by a magnetic field similar to Earth's.