Dynamical maps of Styx, Nix, Kerberos, and Hydra on the a_C–e_C plane of Charon’s initial conditions. On each map, black curves are Charon’s tidal trajectories, obtained for initial e_C values of 0.01, 0.1, and 0.2; the initial conditions of the corresponding moon are fixed at those given in JPL from Table 1. The blue tones represent regular motions, while the brick tones correspond to increasing instabilities and chaotic motion; the colour bar on the top shows Δe. The locations of the main MMRs are indicated.