Evolution of Fragmentation Cloud in Highly Eccentric Orbit Using Representative Objects

Many historical on-orbit satellite fragmentations occurred in Highly Eccentric Orbits (HEOs) such as the Geostationary Transfer Orbit (GTO). Such fragmentations produce fragment clouds that interfere with the Low Earth Orbit (LEO) environment and pose a threat to operational satellites. Objects in HEO undergo complex dynamics due to the influence of perturbations varying as a function mainly of their altitude and area-to-mass ratio. The evolution of such a cloud, including small objects down to 1 mm, is not well understood. This paper describes a method to model the evolution of a fragmentation cloud in HEO under the influence of atmospheric drag and Earth's oblateness. Semi-analytical techniques are applied to propagate represen- tative objects constituting the cloud; rather than following the evolution of many distinct fragments. The proposed method is applied on a GTO upper stage using the standard NASA break-up model to nd the distribution right after the fragmentation. The evolution of the fragment cloud is analysed statistically and time of closures are calculated for the formation of the torus along the parent orbit and the band around Earth. Assumptions on the evolution of the cloud that are valid in LEO are shown to be invalid for clouds in HEO.