Degassing of Comet Analogs: New Laboratory Measurements of Vapor Pressure between Sand–Ice Agglomerates

Abstract This work aims to investigate the rate of production of vapor from the nuclei of comets when they are composed of porous dust–ice agglomerates of different sizes. The reason for starting the research was the discrepancy between the values of vapor pressure between agglomerates required by different theoretical models to reproduce the results of experiments. The model of sublimation of ice from dust–ice agglomerates used in Fulle et al. and Ciarniello et al. assumes zero pressure between agglomerates. However, the generalized model with the pressure between agglomerates being a function of temperature reproduces the results of laboratory experiments when the vapor pressure should not be close to zero. In the present work, we present new experiments including direct measurements of the gas pressure within samples composed of porous agglomerates. The measured pressure is clearly higher than zero. The results of the experiments are compared with the results of mathematical simulations.