Galactic Cosmic-Ray Bombardment of Europa’s Surface

Jupiter's moon Europa is exposed to Galactic cosmic rays (GCRs), highly energetic particles from deep space that constantly bombard its surface. Here we have investigated the effect of GCRs on Europa's surface by carrying out particle physics simulations of secondary particle cascades that occur within surface ice due to incident GCR ions. We find that shielding by the Jovian magnetosphere prevents a significant fraction of the GCR spectrum from reaching Europa. Furthermore, we find that while GCRs are capable of affecting the surface down to depths of at least 10 m, the radiation dose due to these particles is small. Within the uppermost meter of Europa's surface, radiation due to magnetospheric particle bombardment dominates over the GCR dose except for surface locations at high latitudes, where the magnetospheric radiation flux is small.