**DPS Pasadena Meeting 2000, 23-27 October 2000**

*Session 43. Other Planetary Satellites Posters*

Displayed, 1:00pm, Monday - 1:00pm, Friday, Highlighted Tuesday and Thursday, 3:30-6:30pm, C101-C105, C211
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## [43.06] Steady State Convection within Medium-size Icy Satellites

*J. Leliwa-Kopystynski (Institute of Geophysics, University of Warsaw, Poland, and Space Research Center of PAS, Warsaw, Poland), L. Czechowski (Institute of Geophysics, University of Warsaw, Poland)*

We consider the satellites of the size range from Mimas or
Protheus (radii 200 km) to Titania (790 km). The lower limit
is that of the smallest sphere-like bodies. The upper limit
is determined by requirement that no phase transitions
occurs inside the body or these transitions are only of
marginal significance. Therefore, the considered bodies
could be 6 satellites of Saturn, 5 of Uranus, Protheus, and
Charon. Since Miranda is probably a re-accretion product and
density of Protheus is unknown therefore our class of
satellites contains 11 globes in total. Their densities are
known and therefore the mass ratio rock/total and
radioactive heat production can be estimated quite well. Two
extreme models of the satellites are considered:
non-differentiated (homogeneous) and fully differentiated
with rocky core and icy mantle. For the first model there is
a uniform distributions of radioactive sources and the
convection can develop within the whole globe. For the
second case, the radioactivity determines the heat flux
through the boundary between rocky core and icy mantle; in
this case the possibilities of convection are discussed
within the icy mantle. Axially symmetric convection is
considered. The model is based on the equations:
Navier-Stokes, thermal conductivity, mass continuity, and on
the equation of state. They involved a large set of
parameters of which the viscosity is the least known and it
is strongly dependent on temperature. Written in
dimensionless form for constant viscosity the equations have
only one parameter, the Rayleigh number Ra. Set of
solutions, for different Ra, and for constant viscosity or
for temperature dependent viscosity are presented. The
solutions, when converted into dimensional form, are applied
for interpretation of particular tectonic features on the
icy satellites (e.g. Samarkand Sulci on Enceladus and Ithaca
Chasma on Tethys). Correlation between tectonic features and
far-near sides orientation is expected.

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