Short caption: Topographic Map of Chryse Planitia with Location of Possible Buried Basin Discoved by MARSIS
Full caption: This topographic map, based on Mars Orbiter Laser Altimeter data, shows the MARS Express ground tracks and the arc structures detected by MARSIS (Mars Advanced Radar for Subsurface and Ionospheric Sounding) that are interpreted to be part of a buried impact basin about 250 km in diameter. The topographic relief represented in the image is 1 km, from low (purple) to high (red). The projected arcs are shown in red for orbit 1892 and white for orbit 1903. There is no obvious feature in the surface topography that corresponds to the buried feature identified with MARSIS data.

Credit: ASI/NASA/ESA/Univ. of Rome/JPL/MOLA Science Team