关于这张图
About a third of Mars has water ice just below the dusty surface. Figuring out exactly where is vital for future human explorers. One of the ways scientists do this is to look for landforms that only occur when this buried ice is present. These scallops are one of those diagnostic landforms. A layer of clean ice lies just below the surface in this image. As the ice ablates away in some spots the surface dust collapses into the hole that's left. These holes grow into the scallops visible here as more and more ice is lost. Between the scallops, the ice is still there, ready for some astronaut …
