The Bombardment History of the Giant Planet Satellites

• DOI: 10.3847/psj/ad29f4
• Publication Date: 2024-04-02T12:08:26Z
• Authors: William F. Bottke; David Vokrouhlický; David Nesvorný; Raphael Marschall; Alessandro Morbid...; Rogerio Deienno; Simone Marchi; Michelle Kirchoff; Luke Dones; Harold F. Levison
• Keywords: Neptune; Uranus

Abstract The origins of the giant planet satellites are debated, with scenarios including formation from a protoplanetary disk, sequential assembly massive rings, and recent accretion after major satellite–satellite collisions. Here, we test their predictions by simulating outer solar system bombardment calculating oldest surface ages on each moon. Our crater production model assumes projectiles originated primordial Kuiper Belt (PKB) that experienced substantial changes collisional evolution, which transformed its size frequency distribution into wavy shape, Neptune’s outward migration, ejected most PKB objects onto destabilized orbits. latter event also triggered an instability among planets some tens Myr nebula dispersed. We find all missing earliest histories, likely source being impact resetting events. Iapetus, Hyperion, Phoebe, Oberon have few to younger than when Neptune entered (i.e., they 4.52–4.53 Gyr old). remaining midsized Saturn Uranus, as well small located between Saturn’s rings Dione, surfaces still many hundreds (4.1–4.5 A much wider range found for large moons Callisto, Ganymede, Titan, Europa (4.1, 3.4, 1.8, 0.18 old, respectively). At present, favor larger forming within disks, other having several challenges overcome.