  Beneath the icy shell encasing Enceladus, a small icy moon of Saturn, a
global ocean of liquid water ejects geyser-like plumes into space through
fissures in the ice, making it an attractive place to investigate habitability
and to search for extraterrestrial life. The existence of an ocean on Enceladus
has been attributed to the heat generated in dissipative processes associated
with deformation by tidal forcing. However, it remains unclear whether that
heat is mostly generated in its ice shell or silicate core. Answering this
question is crucial if we are to unravel patterns of ocean circulation and
tracer transport that will impact both the habitability of Enceladus and our
ability to interpret putative evidence of any habitability and/or life. Using a
nonhydrostatic ocean circulation model, we describe and contrast the differing
circulation patterns and implied ice shell geometries to be expected as a
result of heating in the ice shell above and heating in the core below
Enceladus' ocean layer. If heat is generated primarily in the silicate core we
would predict enhanced melting rates at the equator. In contrast, if heat is
primarily generated in the ice shell we would infer a poleward-thinning ice
geometry consistent with Cassini Mission observations.
