On Monday, NASA announced a major breakthrough it found flowing on the surface of Mars: liquid saltwater.

This is the first time humans have discovered liquid water on the surface of any planet in the solar system besides Earth, and it is the strongest evidence yet that Mars could support life.

Scientists have suspected for years that liquid water might exist on the surface of Mars, but they had never found direct evidence to support their suspicions.

That changed Monday with a paper that was published in the journal Nature Geosciences.

This groundbreaking discovery not only supports the possibility of current life on Mars, but it is important for potential future manned missions to Mars.

The discovery is "giving us a much better view that Mars has resources that are useful to future travelers," said Jim Green, director of planetary science at NASA Headquarters, during a media briefing on Monday. "The exciting thing is that I think we will send humans in the future ... who will be able to live on the surface and use the resources there."

What's more, water on Mars could "decrease the cost and increase the resilience of human activity on the planet," added Mary Beth Wilhelm, a member of the team announcing the discovery who is at NASA's Ames Research Center in Moffett Field.

Liquid water has many uses:

It can be used for drinking.

It can be used to produce breathable oxygen.

It can help make rocket fuel to launch astronauts off the planet and back home.

How to find water on Mars

A team of scientists used instruments on NASA's Mars Reconnaissance Orbiter satellite to analyze the composition of minerals embedded in dark, deep grooves on the Martian surface around three different regions on Mars.

They discovered that the minerals were a type of salt, perchlorates, and had molecular water in their crystal structure. This suggests that the water is saltwater and not pure.

Here's a GIF showing how these dark grooves change over time, showing evidence of the flow of liquid water:

The scientists think small streams of saltwater flow downhill on the surface of Mars during the warmer summer season, when temperatures can get up to 70 degrees Fahrenheit around the Martian equator.

And as the water flows, it traces these dark grooves in the sand that had been a tantalizing hint of water on Mars.

Now the scientists are positive it's liquid water.

"What that seems to be telling us is that water plays a key role in the formation mechanism of these features," Lujendra Ojha of the Georgia Institute of Technology in Atlanta said. Ojha discovered "possible flows of saltwater on Mars" back in 2011, according to The Verge.

The next step

The scientists do not yet know where this water is coming from and how much of it exists.

"Now that we know what we're looking for, we can begin to better search and look and see if there is an aquifer network supplying these, but that is actually the next step," Michael Meyer, the lead scientist for the Mars Exploration Program at NASA Headquarters, said during the media briefing.