NASA’s Curiosity rover sent back new info that all but confirms Mars was once covered in lakes and streams. This is exactly the information scientists set out to discover. A few years after Curiosity landed on the Martian planet’s surface, we now know that Mars was capable of storing water over an extended period of time—to the point where the Red Planet may have once resembled Earth millions of years ago.

“Observations from the rover suggest that a series of long-lived streams and lakes existed at some point between about 3.8 to 3.3 billion years ago, delivering sediment that slowly built up the lower layers of Mount Sharp,” said Ashwin Vasavada, Mars Science Laboratory scientist at NASA’s JPL.

Even prior to Curiosity’s arrival on Mars, scientists have long suspected the planet was home to ancient lakes. Heck, scientists believe there still might be remnants of water intermittently flowing on the planet today.

This video here might give you a pretty good idea of what a water-covered Mars would have looked like. Much different than the parched landscape we know today.

“Our challenge is to figure out how this more clement Mars was even possible, and what happened to that wetter Mars,” said NASA’s Michael Meyer.

Back in April, NASA revealed that although the surface of Mars is very much barren and withered, it might be a completely different picture underneath, as evidence found by Curiosity suggested water does indeed exist below the surface. However, scientists believe the water is more of a brine, or an extremely salty solution. Hardly the right conditions to support human life.

“During the traverse of Gale, we have noticed patterns in the geology where we saw evidence of ancient fast-moving streams with coarser gravel, as well as places where streams appear to have emptied out into bodies of standing water,” Vasavada said. “The prediction was that we should start seeing water-deposited, fine-grained rocks closer to Mount Sharp. Now that we’ve arrived, we’re seeing finely laminated mudstones in abundance that look like lake deposits.”

The mudstone indicates the presence of bodies of standing water in the form of lakes that remained for long periods of time, possibly repeatedly expanding and contracting during hundreds to millions of years. These lakes deposited the sediment that eventually formed the lower portion of the mountain.

“Paradoxically, where there is a mountain today there was once a basin, and it was sometimes filled with water,” said John Grotzinger, the former project scientist for Mars Science Laboratory at the California Institute of Technology in Pasadena, and lead author of the new report. “We see evidence of about 250 feet (75 meters) of sedimentary fill, and based on mapping data from NASA’s Mars Reconnaissance Orbiter and images from Curiosity’s camera, it appears that the water-transported sedimentary deposition could have extended at least 500 to 650 feet (150 to 200) meters above the crater floor.”

Now that scientists are sure lakes and streams once existed on the planet, it’s now time to figure out where that water went, and where it came from in the first place. “This is a good time to go back to reevaluate all our assumptions,” said NASA scientist John Grotzinger.