The long-term dynamical evolution of Saturn's moon Pallene and its diffuse dusty ring

Pallene is a small moon of Saturn in between the orbits of Mimas and Enceladus. It shares its orbit with a diffuse ring of dusty material. Similar Saturnian satellites—Anthe, Methone, and Aegaeon—are all in corotation resonances with Mimas, but Pallene has not been known to be librating in any resonance. We carry out short-, medium-, and long-term numerical simulations of Pallene and the major Saturnian satellites from Mimas to Titan to explore Pallene's dynamical evolution. We produce diffusion maps through frequency map analysis to gain a better perspective on the dynamical behavior and future stability of Pallene and the dust particles in its neighborhood. First-order resonances with either Mimas or Enceladus in Pallene's neighborhood tend to be unstable regions, and eccentricities of test particles are excited especially in the region near the 6:7 resonance with Mimas and the 5:4 resonance with Enceladus. Because Pallene displaces the test particles near its own orbit, the presence of the diffuse ring suggests that the dust particles are regularly being replenished. We explore possible resonant arguments that influence Pallene's orbital evolution during long-term simulations. Although we do not find a permanent Pallene resonance capture scenario in any simulation, we do observe interesting evolution of some resonant angles, especially between Pallene and Enceladus. We also consider the tidal evolution of Pallene, Mimas, and Enceladus to constrain Pallene's origin and evolution. We do not expect Pallene to be older than a few hundred million years because its semi-major axis would have crossed that of Enceladus, suggesting it could be a fragment from Enceladus.