Mars today is marked by its endless red desert plains. But it was not always like that. There was water and it flowed on its surface longer than previously estimated, a new research by NASA says. The Red Planet rippled with rivers and ponds just like Earth billions of years ago, providing a potential habitat for microbial life. That water, however, evaporated as the planet’s atmosphere thinned over time. It was believed that the water evaporated about three billion years ago. But two scientists studying data, which Mars Reconnaissance Orbiter (MRO) accumulated over the last 15 years, have found evidence which changes the timeline significantly.

Their research has revealed that there was liquid water on Mars as recently as 2–2.5 billion years ago. Which means water flowed on Mars a billion years more than previous estimates. The scientists relied on the chloride salt deposits left behind by the evaporating icy meltwater. Certain valley networks on Mars suggested water flowed there until very recently, but there was no conclusive evidence. The presence of liquid water is confirmed by the salt deposits, which are the first mineral evidence.

The findings have been published in the open-access AGU Advances journal. And they raise interesting new questions, including how long microbial life could have survived on Mars.

The study’s lead author Ellen Leask and Caltech professor Bethany Ehlmann used data from an MRO instrument called Compact Reconnaissance Imaging Spectrometer for Mars to map the chloride salts across Mars’ southern hemisphere. In a report on the NASA website, Ehlmann said the astounding fact was that MRO has led to fresh findings on the nature and timing of these river-connected ancient salt ponds after more than a decade of supplying high-resolution image, stereo, and infrared data.

NASA’s Mars Odyssey orbiter, which was launched in 2001, detected the salt crystals for the first time 14 years ago. MRO, which has higher-resolution instruments than Odyssey, has been studying the salts since its launch in 2005.