NASA: Evidence of water flows on Mars

Although the source and the chemistry of the water is unknown, the discovery could affect thinking about whether the planet that is most like Earth in the solar system could support present day microbial life. The finding is based on a study that was published Monday in Nature Geoscience.

Scientists were intrigued by gullies spotted on Mars in 2011, which they suspected were cut by flowing water. But they had been unable to make measurements to confirm the theory.

Researchers behind Monday's study developed a new technique to analyze chemical maps of the Martian surface obtained by NASA's Mars Reconnaissance Orbiter. 

Lujendra Ojha, a graduate student at the Georgia Institute of Technology and the lead author of the paper, said, “We're not claiming that we found … evidence of liquid water. We found hydrated salts.”

The discovery “confirms that water is playing a role in these features,” explained Alfred McEwen, a planetary scientist with Arizona State University. “We don't know that it's coming from the subsurface. It could come from the atmosphere.”

But the prospect of liquid water, even seasonally, raises the intriguing prospect that Mars, which is presumed to be a cold and dead planet, could support life today.

“Water [in a liquid state] is essential to life as we know it, so finding water is a big step. On Earth, anywhere there's water in nature, there is life, but that isn't necessarily true on the surface of Mars,” McEwen told Al Jazeera.

“The water may be such a dense brine that life can't flourish, and the radiation environment of Mars' surface is detrimental. However, finding the water is step one, and we need future investigations to look for life at these locations,” he added.

NASA's Curiosity rover, which has been exploring the planet's surface since 2012, has found evidence that Mars had all the ingredients and suitable habitats for microbial life to exist at some point in its past.

Scientists have been trying to figure out how it transformed from a warm, wet and likely Earth-like planet early in its history into the cold desert that exists today.

Billions of years ago, Mars, which lacks a protective global magnetic field, lost much of its atmosphere. Several initiatives are underway to determine how much of the planet’s water was stripped away and how much remains locked in ice in underground reservoirs.

Al Jazeera and Reuters. With additional reporting by Ali Younes.