Scalloped landscape on Mars, satellite image. This image shows part of the western Utopia Planitia region on Mars. These scalloped depressions probably form by removal of ice-rich subsurface material by sublimation. This is a similar process to permafrost polygons that form on Earth. These landforms most likely show that sub-surface ice is present or has been present geologically recently. These observations were made by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter spacecraft. Image published in 2017.