A Crater Enlarged by the Sublimation of Ice

This image covers part of the ejecta from an impact crater (about 6-kilometers in diameter) to the west in Utopia Planitia. The ejecta lobes have morphologies suggesting icy flow. Several small (about 100 to 200 meters in diameter) craters on top of those lobes have a distinctive formation. One interpretation is that the impact crater exposed nearly pure water ice, which then sublimated away where exposed by the slopes of the crater, expanding the crater's diameter and producing a scalloped appearance. The small polygons are another indicator of shallow ice. https://photojournal.jpl.nasa.gov/catalog/PIA23759