End-of-life disposal in inclined geosynchronous orbits

The first version (2002) of the Mitigation Guidelines issued by the Inter-Agency Space Debris Coordination Committee (IADC) defined a toroidal Geosynchronous Protected Region, extending 200 km below and above the geosynchronous altitude of 35,786 km, and spanning latitudes in between -15 and +15 deg with respect to the Earth equator. A formula was also proposed (slightly amended in 2007) for the appropriate end-of-life disposal of spacecraft, in order to guarantee no further interference with the protected region over the long-term. These definitions were elaborated when the nearly exclusive utilization of the geosynchronous region consisted of geostationary satellites placed and maintained, during their operational lifetime, close to the Earth equator. When finally abandoned, due to the concurring action of geopotential and luni-solar perturbations, such objects displayed a characteristic periodic orbit plane evolution, with a period of about 54 years and a maximum inclination of about 15 deg. However, significantly Inclined Geosynchronous Orbits (IGO) are currently considered for various applications, like satellite navigation systems, intelligence and telecommunications. In the light of these developments, the aim of this presentation is to review the current definition of the Geosynchronous Protected Region, assessing if it would need an extension. Special attention is paid to the end-of-life disposal, in order to check the potential weaknesses of the current IADC formula and re-orbiting recommendations, focusing on the consequences of having operational orbits characterized by medium or high inclinations.