CAPE CANAVERAL, Fla. (AP) - A new study suggests that dark streaks on Mars are signs of flowing sand - not water.
Monday's news throws cold water on 2015 research that indicated these recurring slope lines were signs of water currently on Mars. Instead, Arizona scientists said these lines appear more like dry, steep flows of sand, rather than water trickling downhill, at or near the surface.
The scientists say if water is present, it's likely a small amount - and not conducive to life.
NASA, meanwhile, says the jury is still out.
The space agency's top Mars scientist, Michael Meyer, says the latest study does not rule out the presence of water. But he acknowledges it's not as exciting as "the idea of rivers going down the sides of cliffs."