KOSI experiments are discussed from the point of view of their possible applications to cometary sciences. Scales and geometries of KOSI and comets are compared, making it obvious that laboratory simulation of any global cometary features is impossible. To indicate the difficulties in process simulation, we discuss in some detail the properties of the gas flow generated by the sublimating ice/dust samples, the interaction of the gas with the emitted grains and heat transport within the sample. Some emphasis is laid on the gas-grain interaction showing that large grains have to be very fluffy (fractal) if gas drag is responsible for their emission. ¿American Geophysical Union 1991