  We discuss a model describing the spin orbit resonance cascade. We assume
that the primary has a two-layer (core-shell) structure: it is composed by a
thin solid crust and an inner and heavier solid core that are interacting due
to the presence of a fluid interface. We assume two sources of dissipation: a
viscous one, depending on the relative angular velocity between core and crust
and a tidal one, smaller than the first, due to the viscoelastic structure of
the core. We show how these two sources of dissipation are needful for the
capture in spin-orbit resonance. The crust and the core fall in resonance with
different time scales if the viscous coupling between them is big enough.
Finally, the tidal dissipation of the viscoelastic core, decreasing the
eccentricity, brings the system out of the resonance in a third very long time
scale. This mechanism of entry and exit from resonance ends in the $1:1$ stable
state.
