An analysis of complex craters on Mercury

We performed a global crater survey that collected geographic coordinates, diameter of the craters, and diameter of the interior complex structure using the mosaic of images captured by the MDIS camera aboard the spacecraft MESSENGER. In this study we identified 20,782 craters across the surface of Mercury. We further classified each crater as simple or complex. Complex craters are subdivided into three main categories: central peak craters, peak ring basins, and central pit craters. A total of 1760 central peak craters were identified, making central peak craters the dominant type of complex crater on Mercury. We find that the median diameter value of central peak craters on Mercury is 38 km, compared to 10 km on Mars. In addition, the diameter of the peak structure in the interior of the crater on Mars is larger relative to the diameter of the host crater than central peak craters on Mercury. Peak ring basins were the second most numerous at a total of 86 identified. Peak ring basins are the largest crater type analyzed in this study and occur most often on Mercury compared to any other body in the solar system. We also identified 32 central pit craters on Mercury, which usually form on volatile rich planets. All central pit craters are summit pit craters, and analysis of the basal peak diameter indicates that summit pit craters on Mercury form by partial collapse of the central uplift in otherwise normal central peak craters. The diameter of the pits are smaller relative to the host crater on Mercury than either Mars or Ganymede. We find that volatiles have no correlation with the formation of central pit craters on Mercury.