As earthlings have begun to explore Mars with our robot spacecraft in orbit and on the ground, one of the most fascinating features we’ve found are the recurring slope lineae.
They can be seen on Mars as long dark streaks, which expand in the martian summertime and then retract again. They’ve been discussed as possible evidence for liquid water, seeping or flowing on Mars today.
New research – published November 20, 2017 in the peer-reviewed journal Nature, now suggests this is not so. The steepness of more than 150 of these features has now been assessed with a powerful telescopic camera on NASA’s Mars Reconnaissance Orbiter.