Three-dimensional subsurface images are revealing structures within the Martian polar ice caps, including previously obscured layering, a larger volume of frozen carbon dioxide contained in the south polar cap, and bowl-shaped features that may be buried impact craters within both polar caps. This information will help scientists better understand Martian climate changes and may allow them to determine the age of the polar caps without using climate models. The 3-D data volumes were assembled from observations by the Shallow Radar (SHARAD) onboard NASA’s Mars Reconnaissance Orbiter (MRO) during more than 2000 orbit passes over each Martian pole.