NASA scientists have taken the discovery of water on Mars another step further, identifying evidence of ancient lakes that existed on the Red Planet.

According to Reuters, authors of a study published in the journal Science identified past activity on Mars similar to that on Earth. They also detailed some of the specific indicators that made the Gale Crater the desired landing spot for the Curiosity rover.

"Observations from the rover suggest that a series of long-lived streams and lakes existed at some point between 3.8 billion to 3.3 billion years ago, delivering sediment that slowly built up the lower layers of Mount Sharp," Ashwin Vasavada, an Mars Science Laboratory project scientist, said in a press release. "However, this series of long-lived lakes is not predicted by existing models of the ancient climate of Mars, which struggle to get temperatures above freezing."

John Grotzinger, a geologist at the California Institute of Technology, told Reuters the researchers "knew that we had a lake there, but we hadn't grasped just how big it was" and that identifying a lake on Mars would be "a very positive sign for life."

NASA was also fascinated by the Gale Crater because of Mount Sharp, which is a remnant of long-occurring erosion taking place in the lakebed.

"Paradoxically, where there is a mountain today there was once a basin, and it was sometimes filled with water," Grotzinger said in the release. "Curiosity has measured about 75 meters of sedimentary fill, but based on mapping data from NASA's Mars Reconnaissance Orbiter and images from Curiosity's cameras, it appears that the water-transported sedimentary deposition could have extended at least 150-200 meters above the crater floor, and this equates to a duration of millions of years in which lakes could have been intermittently present within the Gale Crater basin."