Surface Ages of the Galilean Satellites of Jupiter: the Case of Ganymede

Abstract

The icy Galilean satellites of Jupiter, Europa, Ganymede and Callisto will be the targets of intense study by orbiting spacecraft in the near future: NASA’s Europa Clipper (planned insertion into Jupiter orbit on April 11, 2030 [1]), and ESA’s JUICE (Jupiter orbit and Ganymede orbit insertion 2031 and 2034, respectively [2]). Examining the crater distributions on a planetary body is a general method to infer its geologic evolution. The sparsely cratered, tectonically intensely deformed and comparably young surface of Europa [3] provides a strong contrast to the surfaces of Ganymede [4][5] and Callisto [6] with vast expanses of dark, densely cratered plains most likely dating back to a distant past. Since no surface material from these bodies is available todate, absolute surface ages can only be derived from impact chronology models. In this study we focus on Ganymede featuring dark, densely cratered plains and bright, less cratered tectonized units, using various impact chronology models, including a recently updated model [7][8][9].