The Enceladian crater production function

Abstract

Interpreting Enceladus&#39;s past and present surface history and interior state remains challenging, owing to uncertain prescription of its impact bombardment history and limited interpretation of its crater statistics. Further progress in understanding its evolutionary history can be achieved with an improved crater chronology model and a thorough assessment of Enceladus&#39;s surface. Here we present the first step in the form of a comprehensive, global crater catalogue with geomorphology survey for Enceladus. From our dataset we build the crater production function (CPF), which is the underlying, unmodified crater size-frequency distribution of the satellite surface, assuming no subsequent modification. We obtained the CPF with a data-driven approach; therefore it makes no assumptions about the impactor source population or planet evolution models or the timing of impact. We fit the CPF with a high-order polynomial as is customary for the Moon and Mars, capturing the slope variations across different crater diameter ranges. The Enceladian CPF generally has a steeper cumulative slope than that of the Moon and Mars for small crater diameters D_cr < 10 km, as well as that of the size-frequency distribution of trans-Neptunian objects. This CPF serves as a critical observational input for an Enceladian crater chronology model, enabling the conversion of crater densities into absolute surface ages. Extending the crater cataloguing and CPF derivation of this study to other Saturnian satellites will determine whether the Enceladian CPF is unique; a shared CPF would indicate a common impactor population, providing observational constraints on the size-frequency distribution of small bodies in the outer Solar System.