Laboratory investigation of the evolution of cometary analogs: Results and interpretation

Kossacki KJ, Kömle NI, Leliwa-Kopystyński J, Kargl G


128(1), 1997, 127-144, 10.1006/icar.1997.5701

The thermal and structural evolution of multicomponent ice/mineral samples due to surface radiative heating has been investigated experimentally. The components of the samples were water ice, carbon dioxide ice, and dunite. Starting with originally homogeneous mixtures, we observed the sublimation of different volatiles under low pressure and low temperature conditions. This process resulted in the formation of stratified samples, containing clearly divided regimes with different chemical composition and cohesivity. A new computer model, developed along the lines of our previous work, is applied to provide a quantitative description of the observed temperature evolution and stratification within the samples. These processes may play a key role in the formation of surface layers of cometary nuclei. Within the ROSETTA mission, several already accepted experiments aim at a direct (in situ) investigation of just these near-surface layers on the nucleus of Comet P/Wirtanen. Therefore, both the rather generally applicable thermal model and the particular results of our laboratory experiments may provide useful support for the design of these experiments.