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E. Ammannito (INAF-IFSI), M.T. Capria (INAF-IASF), A. Coradini (INAF-IFSI), M.C. De Sanctis (INAF-IASF)
Does Vesta have a polar cap?. This is unknown. As a study for the Dawn mission, in order to understand thoroughly this asteroid, we have developed an accurate model. We will present results obtained using a thermal evolution model of the Vesta surface, in particular we have investigated the possibility of Vesta polar caps. The model used here is derived from the model developed for the study of the thermal evolution of a comet nucleus. The model is based on the numerical solution of the heat transport and gas diffusion equations within a porous body, coupled through the sources. In fact, the sublimating gases are carrying matter and energy, therefore these two aspects of the same process are introduced as sinks and sources in the two conservation equations. Moreover, in the solution of the heat diffusion and gas equations, sublimation and re-condensation processes are taken into account, as well as the possible phase transitions of all of the ices present in the matrix. The gas diffusion equation is solved only in the upper layers of the polar region, since we think that the presence of ices is relevant only on a thin superficial shell in the polar regions. In addition, the erosion of the layer interfaces within the porous body is numerically treated by means of discrete grid, adapted continuously to the interface positions, removing numerical instabilities associated with the variation of structure and composition of the discrete layers. By applying this model to a thin layer on the surface of Vesta, we are then able to see its evolution.
The author(s) of this abstract have provided an email address for comments about the abstract: mail:eleonora.ammannito@rm.iasf.cnr.it
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.