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A. Enzian, P.R. Weissman (JPL, Caltech)
A multidimensional comet nucleus model is used to estimate the temperature and gas production distributions on the surface of cometary nuclei in the orbits of comets 46P/Wirtanen and 9P/Tempel~1. These comets are the targets respectively of the Rosetta and the Deep Space~4/Champollion comet rendezvous missions. The spherical model nucleus is assumed to be made up of a porous dust-ice (H2O, CO) matrix. Heat and gas diffusion inside the rotating nucleus are taken into account in the radial and meridional directions. A quasi-3D solution is obtained through the dependency of the boundary conditions on the local solar illumination as the nucleus rotates. As a study case, we consider a homogeneous chemical composition of the surface layer which is assumed to contain water ice. The model results include the distributions of temperature and gas production on the surface. For the chosen test case of a nucleus spin axis perpendicular to the orbital plane we find that the CO gas production on the surface is quasi-uniformly distributed, in contrast to the non-uniform water outgassing. The mixing ratio at any specific point on the comet nucleus surface is not representative of the overall mixing ratio which is observed in the coma.\\
\noindent This work is supported in part by the NASA Planetary Geology and Geophysics Program.
The author(s) of this abstract have provided an email address for comments about the abstract: Achim.Enzian@jpl.nasa.gov