From Earth, lifeless Mars can seem like a serene and boring planet. However, scientists noticed some little black dots in a satellite image of the Martian sand that may hint at an exciting, explosive geography. You are 200 miles directly above the Martian surface — looking down. This image was taken by the Mars Reconnaissance Orbiter on Jan. 27, 2010. (The color was added later.) What do we see? Well, sand, mostly. As you scroll down, there's a ridge crossing through the image, then a plain…