Rachmaninoff double-ring basin on Mercury

Rachmaninoff double-ring basin on Mercury
Rachmaninoff double-ring basin on Mercury On approach to its third flyby, MESSENGER captured a photo of a double-ring basin only partially imaged during the previous encounter. Craters on Mercury larger than 200 kilometers in diameter tend to be double-ring basins; this one is 260 kilometers across. Originally the basin would have had a rough floor; it is now filled with "smooth plains," likely lava flows. The center of the basin is cut by troughs that are concentric to the crater rim, which are probably tectonic in origin, formed as a result of stresses within Mercury's crust. Such concentric troughs (which form when the crust extends) within craters are rare on Mercury, whose surface tectonics are mostly compressional, resulting from Mercury's entire crust shrinking. The crater was later named Rachmaninoff. NASA / JHUAPL / CIW