Surface of section of Hamiltonian ${\widehat{\mathscr{H}}}^1$ using the L and Λ′ values of Cassini Flyby 2. Librational solutions around the main nutation-orbit resonances are plotted in blue, while secondary resonances are shown in gray. A large chaotic sea (purple) surrounds the 3:1 resonance; a smaller chaotic separatrix surrounds the 4:1. At rapid spin rates, many invariant tori are preserved (black).