A piece of Mars: Small dunes (or possibly ripples) are likely no longer moving in today’s winds. Or are they? Dark splotches on their upper (northern) sides suggest some kind of wind scour has recently occurred. Winds blow, create dunes, then stop blowing, only to later strengthen and reactivate, destroy, bury, or overwrite older dunes. This seems to be a theme in many of my images. But that’s probably because it seems to be a theme for Mars. (HiRISE ESP_028288_1720)