Criscrossing the south polar region of Mars, cracks and ridges line the frozen ground, broken by the occasional spray of dark material spewed by a geyser of released subsurface gases. These lines are referred to as “spider troughs” due to their resemblance to cobwebs, as seen from the Mars Reconnaissance Orbiter.
This image was taken by the HiRISE camera on December 27, 2008. Click here for a color close-up.
Image credit: NASA/JPL/University of Arizona