  Europa is an icy ocean world, differentiated into a floating ice shell and
solid interior, separated by a global ocean. The classical spin-orbit coupling
problem considers a satellite as a single rigid body, but in the case of
Europa, the existence of the subsurface ocean enables independent motion of the
ice shell and solid interior. This paper explores the spin-orbit coupling
problem for Europa from a dynamical perspective, yielding illuminating
analytical and numerical results. We determine that the spin behavior of Europa
is influenced by processes not captured by the classical single rigid body
spin-orbit coupling analysis. The tidal locking process for Europa is governed
by the strength of gravity-gradient coupling between the ice shell and solid
interior, with qualitatively different behavior depending on the scale of this
effect. In this coupled rigid model, the shell can potentially undergo large
angular displacements from the solid interior, and the coupling plays an
outsize role in the dynamical evolution of the moon, even without incorporating
the dissipative effects of shell non-rigidity. We additionally discuss the
effects of a realistic viscoelastic shell, and catalogue other torques that we
expect to be sub-dominant in Europa's spin dynamics, or whose importance is
unknown. Finally, we explore how the choice of tidal model affects the
resulting equilibrium spin state.
