The paper presents experimental studies on the degassing of porous ice and porous mixtures of ice and sand in a vacuum. The study aims to find the relationship between the surface recession rate and the subsurface temperature gradient as well as the granulation and composition of the material. We propose an empirical equation tested on samples with a mass fraction of non-volatile material to ice in the range of 0–3.65. Based on the proposed equation, calculations were carried out, which indicate the possibility of landslides on the inclined areas on the surface of comet 9P/Tempel 1.