Comets, sliding of surface dust II

In this paper we presented the results of laboratory experiments dealing with the sliding of desiccated sand on the inclined surfaces of cometary analogs. The experiments were performed in a vacuum, using porous mixtures of water ice and quartz sand. The inclination angle of the surfaces of the samples was about 10 degrees lower than the repose angle. The sliding was possible when the mobility coefficient defined as the ratio of forces was lower than unity i.e. when the layer of sand as the whole was not fluidized. The observed effect of sliding was due to the rolling, or sliding of grains present on the surface. It is important, that the process of sliding of desiccated sand can be caused by the sublimation of underlying water ice despite its relatively low volatility.