Dispersion of debris clouds from on-orbit fragmentation events

The fragmentation of a satellite creates numerous debris. A new approach is chosen to model in four phases the dispersion of an ensemble of particles which originates from a common breakup point. During the first revolutions the ensemble is represented as a pulsating ellipsoid in an orbiting reference system (phase A). Within a few hours, the cloud spreads out to the shape of a torus (phase B). Due to the nonsphericity of the earth, different drift rates in ascending node and argument of perigee cause the torus to open to a band limited in latitude by the inclination of the parent satellite (phase C). In the last phase (D), starting after complete nodal and apsidal dispersion, only the cleaning effect of air drag has to be considered. Consequences for the LEO environment of fragmentations like that of the Ariane V-16 third stage in 1986 are investigated. Spatial density and collisional risk diminish quickly in the direct vicinity of the breakup point, but remain significant for years in a broad environment.