Woohoo!! Something’s flowing down a gully in an impact crater and Mars and it might be water! NASA and Malin Space Science Systems today announced that their scientists may have found evidence of flowing liquid water, possibly in the form of an icy, slushy, muddy flow that spread about 5-10 swimming pools worth of water across the surface at the mid-latitudes of Mars!
The scientists are not yet sure what the mechanism is behind the flowing material, but one possible scenario has flowing liquid squirting out from broken layers of rock in impact craters. As it does, it forms gullies and deposits sand, silt, and minerals in the flow path. The water itself forms fog, mist, and water droplets that freeze into crystals.
How do we know this is a liquid flow and not a landslide? Scientist Ken Edgett pointed out the differences between how a landslide looks on Mars and how a feature created by flowing water looks. The liquid that flowed across the surface most likely had sediments in it, sort of like a mudflow. The way it moved down the 20- to 30-degree slope in the crater in the image indicates that it had to be water. The brightness of the flow feature is very unusual. In landslides and impact craters, material that is turned up from below the surface is usually dark.
If this feature was a landslide, it would be darker. The material we see is lighter, which indicates that it could be water that flows out from underground, hits the cold air and low-pressure atmosphere and turns into a frothy stream. Or, it could also be water with salts and other minerals entrained in it. Either way, it’s quite likely that the flow has water in it.
If this is a water flow, how is the liquid getting out? What’s causing the flow? The scientists are still debating the sources: subsurface aquifers, melting snow, or ground ice (which does require something to melt it). It’s still unclear why the water is flowing; now we need to figure out why.
The interesting thing is that these water flows are coming out of the walls of impact craters. The force of a collision weakens rock, and any aquifers would then find a ready outlet for flowing water through the broken, cracked rock.
There’s still a lot to learn, but the cool story is that we now have proof of flowing water on Mars.
The other find announced today was the discovery of at least 20 very recent impact craters on Mars. The collisions occurred sometime between May 1999 and March 2006. This is an interesting juxaposition of finds; both may help scientists understand the story of water on Mars and the very real, daily events that continually change the Martian surface. Stay tuned!