Collision risk mitigation in geostationary orbit

The short and long-term effects of spacecraft explosions, as a function of the end-of-life re-orbit altitude above the geostationary orbit (GEO), were analyzed in terms of the additional contribution to the debris flux in the GEO ring. The simulated debris clouds were propagated for 72 years, taking into account all the relevant orbital perturbations. The results obtained show that 6-7 additional explosions in GEO would be sufficient, in the long-term, to double the current collision risk with sizable objects in geostationary orbit. Unfortunately, even spacecraft reorbit in between 300 and 500 km above GEO would not improve significantly the situation and an altitude increase of at least 2000 km should be adopted to reduce by one order of magnitude the long-term risk of collision among geostationary satellites and explosion fragments. The optimal debris mitigation strategy should be a compromise between the reliability and effectiveness of spacecraft end-of-life passivation, the re-orbit altitude and the acceptable debris background in the GEO ring. However, until the re-orbit altitudes currently used will be less than 500 km above GEO, new spacecraft explosions will have to be absolutely avoided for the long-term preservation of the geostationary environment.