In a paper published in the journal Nature Geoscience, Dr. McEwen and other scientists identified waterlogged molecules — salts of a type known as perchlorates — in readings from orbit.
"That's a direct detection of water in the form of hydration of salts," Dr. McEwen said. "There pretty much has to have been liquid water recently present to produce the hydrated salt."
Though young Mars was inundated by rivers, lakes and maybe even an ocean a few billion years ago, the modern moisture is modest. Scientists have long known that large amounts of water remain — but frozen solid in the polar ice caps. There have been fleeting hints of recent liquid water, like fresh-looking gullies, but none have proved convincing.
[T]hat strengthens the possibility of finding microbial life on the Red Planet. The presence of liquid water on Earth is intimately linked with the formation of life, so the odds are better than ever that extraterrestrial organisms are nearby in our Solar System.This is mind-blowing, eye-popping news.