Scientists have found salty liquid water flowing on the surface of present day Mars.

The discovery, published online on Sept. 28 in the journal Nature Geoscience, opened possibilities of life existing in the planet. An image by NASA's Mars Reconnaissance Orbiter (MRO) showed dark narrow streaks called recurring slope lineae (RSL) originating from the walls of Mars' Garni crater, according to Space.com. These streaks are said to be caused by liquid water.

"This is tremendously exciting," James L. Green, the director of NASA's planetary science division, said during a news conference on Monday, as quoted by The New York Times. "We haven't been able to answer the question, 'Does life exist beyond Earth?' But following the water is a critical element of that. We now have, I think, great opportunities in the right locations on Mars to thoroughly investigate that."

The study's lead author, Lujendra Ojha of the Georgia Institute of Technology in Atlanta, told Space.com via email that liquid water is a key requirement for life on Earth to thrive. "The presence of liquid water on Mars' present-day surface therefore points to environment[s] that are more habitable than previously thought," Ojha said, as reported by the news outlet.

Ojha and his colleagues first discovered RSL in 2011 through the images captured by the High Resolution Imaging Science Experiment (HiRISE) camera, which was on board NASA's MRO, Space.com noted.

RSL take place in various locations on Mars, "from equatorial regions up to the planet's middle latitudes," Space.com added. These streaks are just 1.6 feet to 16 feet (0.5 to 5 meters) wide, but have the capacity to extend for hundreds of meters downslope. In addition, RSL streaks appear during warm weather but disappear when temperatures drop, pushing scientists to consider that liquid water is involved in their formation.

Study co-author Alfred McEwen of the University of Arizona said that the features found aren't exactly "burbling streams," more like "wet soil, thin layers of wet soil, not standing water," the news outlet further reported. Researchers identified RSL-associated salts known as perchlorates, a chlorine-containing substance prevalent in the planet. The property increases the stability of brine on Mars.

John M. Grunsfeld, NASA's associate administrator for science, said that they are discussing sending a spacecraft to one of Mars' regions in the 2020s, probably with experiments meant to look for life, The New York Times wrote.

Mars had lakes, rivers, and maybe an ocean a few billion years ago, but current moisture is modest and only small patches of damp soil appear, not pools of standing water. Scientists have also known that large amounts of water remain in Mars, but it was frozen solid in the polar ice caps, the news outlet added.