New NASA images show “tendrils” of what appears to be mud flowing down hillsides, researchers say. “It's hard to imagine they are formed by anything other than fluid seeping down slopes,” notes one scientist. The cold temperatures when the tendrils appear suggest they aren’t fresh water, the BBC reports. “The best explanation we have for these observations so far is flow of briny water, although this study does not prove that,” says the lead researcher.
“Liquid water is absolutely essential for life, and we've found life on Earth in pretty much every moist niche,” says an astrobiologist who wasn’t part of the study. “So perhaps there could be hardy microbes surviving in these short periods of summer meltwater on the desert surface of Mars.” The findings are the closest we have to evidence of liquid water on the planet, NASA notes. Click through to the agency’s website for video of the Mars flows.