Mysterious water-like streaks on Mars might be sand flows instead | New Scientist
https://www.newscientist.com/...5-mysterious-water-like-streaks-on-mars-might-be-sand-flows-instead/
The mysterious dark flows on Mars may not be water after all. Instead, they could be rivulets of sand,
set in motion by sunlight on the Martian surface.
The dark streaks form on Mars’s slopes during warm seasons, and are known as recurring slope lineae. While there is no direct evidence
of water near these areas, the leading theory is that they are caused by briny water streaming down the sides of craters and hills.
“These effects happen at the hottest times in the hottest locations, so there’s part of your brain that immediately tells you that it
should be ice melting,” says Sylvain Piqueux at NASA’s Jet Propulsion Lab in Pasadena, California. “The problem is, it’s really hard
to melt ice on Mars.” It’s easier for the ice to turn directly into water vapour, he says.
Some models suggest that recurring slope lineae could be made of water condensing out of the atmosphere,
but Mars’s atmosphere isn’t humid enough to account for what we see.
