NASA scientists have found compelling evidence that leads them to believe liquid water is present in Mars. Dark, narrow gullies on the surface of Mars contain water-bearing salts. This could only happen from water flowing downhill on the surface of the red planet, according to researchers.

The discovery was made thanks to NASA’s Mars Reconnaissance Orbiter, and it marks the first time that a planet outside of our own has the real possibility of hosting microbial life in this water.

“Of all the worlds we’ve explored, water flows only on the surface of one – ours. Which is why the discovery that water is now likely to be regularly flowing across Mars is so stunning,” said Swinburne University of Technology astrophysicist Alan Duffy.

Reaching this conclusion wasn’t at all easy though. Researchers developed a new technique to study the chemical maps on Mars’ surface. They utilized the MRO’s instruments to analyze the chemical composition of these dark streaks, or gullies, that were coming out of the Garni crater.

When they were compared to the nearby terrain, the CRISM instrument only detected these water-bearing salts on the gullies, and not in other areas. These slopes have been observed since 2011 but had never been able to be tested until now. Scientists are confident that they were cut by flowing water at some point in Mars’ history.

Of course, nowadays, Mars’ atmosphere is incredibly cold and thin. Any liquid water that makes it to the surface would either freeze or evaporate, but this new discovery shows that water might be able to exist briefly under the right salty conditions.

The full study was published on Nature Geoscience and is totally worth a read if you’re into it.