Small Expanded Craters in the Northern Lowlands

This image shows many small craters over a larger degraded one in the northern lowlands. These small craters are smoother and shallower than their counterparts closer to the equator.

Scientists believe this difference is a result of impact into a region with subsurface ice, which sublimates when exposed to the Martian atmosphere. This causes the crater to gradually expand and flatten after impact.

Written by: HiRISE Targeting Specialists (audio: Tre Gibbs)   (24 August 2016)

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Image: NASA/JPL/University of Arizona