Collision risk associated with instability of MEO disposal orbits

Recent studies show that medium Earth orbit (MEO) disposal orbits, such as those recommended by the U.S. Government Debris Mitigation Guidelines, are unstable, resulting in penetration of the operational constellation by the disposal orbit perigees. The purpose of this study is to obtain an understanding of the associated collision risk posed to the operating Global Positioning System (GPS) constellation. Collision risk was assessed via direct statistical analysis of conjunction miss-distances. Study results include typical time histories of constellation penetration by disposal orbit perigees, estimates of collision risk growth over 200 years for the proposed 832 km disposal orbit, and variation of collision risk with disposal orbit plane and altitude.