This January 14, 2011 image from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter show portions of the Martian surface in unprecedented detail. This one shows many channels from 1 meter to 10 meters (approximately 3 feet to 33 feet) wide on a scarp in the Hellas impact basin. On Earth we would call these gullies. – AFP Photo

WASHINGTON: Scientists have spotted dark stripes on some slopes on Mars in the warmer months, and they believe it may be evidence of flowing salt water, NASA researchers said on Thursday.

If confirmed, it would be the first discovery of active liquid water in the ground on Mars.

Finger-like markings have shown up along several steep slopes in the middle latitudes of Mars’ southern hemisphere, fading again once colder temperatures move in, according to data from NASA’s Mars Reconnaissance Orbiter.

“The best explanation we have for these observations so far is flow of briny water, although this study does not prove that,” said Alfred McEwen of the University of Arizona’s Lunar and Planetary Laboratory.

“It’s a mystery now, but I think it’s a solvable mystery with further observations and experiments,” said McEwen, lead author of a study explaining the findings in the journal Science.

NASA experts are still not sure if what they have witnessed is actually water flowing on the red planet, where no liquid water has ever been found to date.

“By comparison with Earth, it’s hard to imagine they are formed by anything other than fluid seeping down slopes,” said Mars Reconnaissance Orbiter Project Scientist Richard Zurek of NASA’s Jet Propulsion Laboratory.

“The question is whether this is happening on Mars and, if so, why just in these particular places.” Frozen water has been detected in some of Mars’ higher latitudes, and other evidence has suggested that water interacted with the Martian surface throughout the planet’s history.