Introduction

In 2015 the International Astronomical Union (IAU) named the impact crater shown in this image mosaic from the High Resolution Stereo Camera (HRSC) after the US scientist Ronald Greeley, who passed away in 2011. Greeley was a pioneer in the field of planetary geology, which he taught and researched at Arizona State University from 1977 onwards. From the very outset, in 1988, Greeley was also a member of the HRSC experiment team –first on the unsuccessful Russian mission Mars 96 and then on the follow-up Mars Express mission, operated by the European Space Agency (ESA).