KOSI: Gas drag derived from ice/dust-particle trajectories

Trajectories of the emitted ice/dust particles were successfully monitored by a high speed shutter video camera during the large scale experiment KOSI-5 (Nov.1989) performed in the DLR Space Simulator. These new results complement and quantify the high resolution observations of the surface obtained previously in the small chamber. The particles are coupled rather then loosely deposited on the surface. The authors conclude that the particle dynamics is dominated by the acceleration during their flight. This acceleration is caused by the momentum transfer from the gas sublimating from the sample. The net observed acceleration in the direction normal to the surface is in the range 10-20 m/sec2. The ice/dust particles appear to be entrained into the gas flow, rather than ejected from the surface