Influence of the spacecraft end-of-life re-orbiting altitude on the long-term collision risk in the geostationary ring Original Research Article

A novel approach was developed to assess the contribution of satellite explosions to the object density in the geostationary ring. A low intensity explosion of a typical operational spacecraft was simulated at eight different altitudes, in between 0 and 2000 km above the geostationary orbit (GEO). The fragments produced were propagated for 72 years, taking into account all the relevant perturbations, and their contribution to the average object density in the GEO ring, both short and long-term, was analyzed as a function of the end-of-life re-orbiting altitude. The explosions in geostationary orbit are the most detrimental for the GEO ring environment. However, the average fragment density in the ring is never higher than 15 of the current background, decreasing to less than 1100 of the existent environment after 4 years, apart for the density rebound, about five decades later, due to the luni-solar perturbations. The spacecraft end-of-life re-orbiting is a possible mitigation solution, but the long-term situation improves quite slowly, as a function of the altitude above GEO, if the explosions continue to occur. A re-orbiting 300 km above the geostationary altitude seems adequate to guarantee, after 2 – 4 years, a long-term average density of fragments in the GEO ring at least two orders of magnitude below the present-day background, even during the density rebound observed after 54 years. However, at least 1000 km of re-orbiting are needed to stay below that 1100 threshold also in the short-term.