NASA presented Thursday what may be the strongest evidence yet of liquid water on the surface of Mars.

Pictures taken by the powerful HiRISE camera aboard the Mars Reconnaissance Orbiter (MRO) showed fingers of dark material running down rocky slopes facing the equator during spring and summer months. Scientists believe that this represents a significant sign that briny water is flowing on the surface of the red plant.

The dark stripes, approximately 0.5 yards wide and hundreds of yards long, appear during the warm months and then disappear again in cold months. The salty surface of Mars means that liquid water would be salty as well, making it less likely to freeze at the observed tempratures.

"These dark lineations are different from other types of features on Martian slopes," MRO project scientist Richard Zurek said in a press advisory. "Repeated observations show they extend even farther downhill with time during the warm season."

Lead researcher Alfred McEwen told Discovery News the latest pictures were not a smoking gun and laboratory tests could provide more evidence.

"Whether this is related to Mars' habitability or not, I think you'd need a lander or something to go investigate in more detail. This (discovery) provides places where there is water accessible to the surface," he added.

"What's really exciting to me is that it shows a new active phenomenon on Mars. It shows how little we really know."

Watch this video from NASA.