Ripples in a crater

A piece of Mars: Many small craters on Mars are filled, at least in part, by small dunes or ripples. It’s one of the distinguishing features of Mars — a surface marked by geology both old (craters) and young (dunes). This particular crater isn’t so old — boulders surrounding it were made from rocks flung from the impact when it formed, and they are usually one of the first things to erode away as a crater ages. (HiRISE ESP_026726_1790)