Results from Comet Nucleus Model Team at the International Space Science Institute, Bern, Schwitzerland.

Kurzfassung

Five one-dimensional algorithms for heat and gas transport in porous icy bodies have been applied, each to four simplified compositions of comet nucleus models: (1) pure H2O ice, (2) a mixture of H2O and CO ices, (3) a mixture of H2O ice and dust, and (4) a mixture of H2O and CO ices and dust. In addition, two different pore radii were assumed in models 3 and 4. The algorithms were chosen on the basis of recent applications and independent code development and evolution. A sixth algorithm was used only in a few models. Results for spinning comet nucleus in the orbit of Comet 46P/Wirtanen were compared to establish credibility of the five algorithms. Discrepancies in results were discussed and isolated for possible causes. The algorithms were then investigated and modified by the presenting team members. After resolution of major differences from the simple models, each team member will be able to address more complex models of their own choosing with greater confidence. These models will include investigations of the effects of amorphous versus crystalline water ice, trapped gases versus frozen gases, multi-dimensional calculations, and dust mantle development and removal. Results and progress on the algorithms, and plans for further development are discussed.