Assessment of the on-ground risk during re-entries

The present paper outlines methods which allow to quantify and monitor the on-ground population risk in the course of a hazardous re-entry event. The risk potential will be derived from an object related casualty cross-section, the endangered ground swath, and the underlying population density. Means will be described to perform a long-term risk assessment for a given latitude band, and a short-term risk assessment for a given nodal longitude of the final re-entry orbit. In case of residual manoeuvring capabilities strategies will be outlined to manage and reduce the risk potential by controlling the nodal longitude of the final orbit, and the impact footprint. The usefulness of these concepts will be demonstrated for the historic re-entries of Skylab and Salyut-7, and for the recent re-entry of the Mir space station.