The Zooniverse is going back to Mars with Planet Four: Ridges. 

We need your help to find polygonal ridges (intersecting lattices of thin ridges enclosing polygonal shapes) on the Martian surface. Polygonal ridges are rare, but with more locations discovered we can start to figure out how they formed and whether past water on Mars’ surface played a role. Computers are not good at spotting these features in images from orbit, but the human eye can.

Explore the Red Planet today at