http://www.space.com/12543-mars-myst...alt-water.html
Salt water could be running down some slopes of Mars every spring, researchers suggest.
Such a finding would suggest new directions to search for any life that still existed on the Red Planet.
Clusters of dark, narrow lines that periodically emerge and lengthen on slopes in the warmer regions suggest briny water on Mars might still be flowing in a few rare places on the planet's surface.
"This is water today, not in the past," study co-author Alfred McEwen, a planetary scientist at the University of Arizona, told SPACE.com. [Photos: The Search for Water on Mars]
A great deal of evidence on the Martian surface suggests the planet was wet and perhaps capable of supporting life in the past. Although frozen water has been detected near the surface in many middle-to-high latitudes, there has been no definitive evidence that liquid water still runs across its surface.
"Water today on Mars was suggested previously, but it's not clear if those claims withstood follow-up studies," McEwen added. "That may prove true with this case as well, but for now, this is the best candidate for water today on Mars."
The scientists discovered the strange lines after a University of Arizona student used a computer algorithm on pictures of the Martian surface taken by the High Resolution Imaging Science Experiment (HiRise) on the Mars Reconnaissance Orbiter. The algorithm was capable of identifying subtle changes on Mars over time. The images covered a variety of latitudes and span across approximately three Martian years.
The student, Lujendra Ojha, said in a statement: "I was baffled when I first saw those features in the images after I had run them through my algorithm. We soon realized they were different from slope streaks that had been observed before. These are highly seasonal, and we observed some of them had grown by more than 200 meters [650 feet] in a matter of just two Earth months." [FAQ: What the Possibility of Water on Mars Means]
These finger-like streaks extend down some slopes during the warmest months of the Martian year. They fade in winter, then re-emerge in the spring.
"What's most interesting to me is that it took so long to discover these details from images that were seen or acquired long ago but not examined in detail long ago," McEwen said. "It makes me wonder how many other things we're missing."
These features, called "recurring slope lineae," reach down steep slopes such as the rims of impact craters, usually on sides facing the equator. While they can be hundreds of feet long, they are only about 1.6 to 16 feet (0.5 to 5 meters) wide, much narrower than gullies seen in the past on Martian slopes.
The scientists detail their findings in the Aug. 5 issue of the journal Science.
Evidence of Present-Day Liquid Water On Mars?
(https://chiefsplanet.com/BB/showthread.php?t=248070)