Flowing Water On Mars

NASA scientists announced today that they’ve assembled strong evidence that liquid water flows on the Martian surface. There isn’t any indication that this means there’s life on Mars, but when you keep in mind that everywhere we find water on Earth we find living things, it’s exciting stuff.

After studying years worth of images collected by the Mars Reconnaissance Orbiter, a particular feature jumped out (tour the gorgeous HiRise image library at beautifulmars). Dark streaks called Recurring Slope Lineae (RSL) appeared on a seasonal basis, coinciding with conditions that could support liquid water in the form of salty brines.

Animation of seasonal flows in Hale Crater:

Think of these RSL streaks (visible in the image gallery up top) like water flowing downhill through sand, causing it to change color as the wet stuff seeps toward the valleys below. If you’re picturing rushing rapids, it’s really more like a wet sponge. These brines, made of chlorate and perchlorate minerals, are much saltier than our own seas, which allows this water to remain liquid in Mars’ frigid climate. Saltwater is especially intriguing for astrobiologists, as salty stuff has higher odds than freshwater for supporting biological chemistry.

NASA billed this report of liquid saltwater as “major”, but this isn’t the first news of water on Mars. Martian hydrology has a long, exciting history. As far back as Mariner 9, dry river and lake beds suggested that the red planet was once much wetter, and later missions told of an ocean-covered Mars several billion years ago. As recently as April 2015, the Mars Curiosity rover found similar brines near the surface at night. We’ve also known for a while that the Mars of today is home to significant amounts of frozen water ice, enough to cover the planet in a thin, wet, puddle if it melted. 

What makes today’s announcement so interesting isn’t that water exists on Mars, but that it still flows near the surface on a seasonal basis. Mars super-thin atmosphere led many to believe that any liquid water near the surface would boil away, and the dynamic nature of the wet stuff means that we’ve got a lot to learn about our planetary neighbor.

Read more at The Atlantic, The New York Times, and io9.


#Mars #the power of science #the more you know

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