  Over the south pole of Enceladus, an icy moon of Saturn, geysers eject water
into space in a striped pattern, making Enceladus one of the most attractive
destinations in the search for extraterrestrial life. We explore the ocean
dynamics and tracer/heat transport associated with geysers as a function of the
assumed salinity of the ocean and various core-shell heat partitions and bottom
heating patterns. We find that, even if heating is concentrated into a narrow
band on the seafloor directly beneath the south pole, the warm fluid becomes
quickly mixed with its surroundings due to baroclinic instability. The warming
signal beneath the ice is diffuse and insufficient to prevent the geyser from
freezing over. Instead, if heating is assumed to be local to the geyser,
emanating from tidal dissipation in the ice itself, the geyser can be
sustained. In this case, the upper ocean beneath the ice becomes stably
stratified and thus a barrier to vertical communication, leading to transit
timescales from the core to the ice shell of hundreds of years.
