However, MRO has observed other Martian features that do seem associated with liquid water - dark streaks known as recurring slope lineae.
RSL lines snake down crater walls and other slopes during warm weather on the Red Planet, and some researchers think they're caused by briny water that contains an iron-based antifreeze. Direct evidence of flowing water at RSL sites, however, remains elusive.
If water does flow across the surface of present-day Mars from time to time, the planet would be a likelier bet to host life as we know it. Here on Earth, life teems pretty much anywhere liquid water exists.
Ancient Mars was much more hospitable to life. For example, NASA's Curiosity rover discovered an ancient lake-and-stream system near its Red Planet landing site that could have supported microbial life billions of years ago.
Originally published on Space.com.
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