Position paper on space debris mitigation

Bonnal C., Flury W., Hussey J., Anselmo L.

Space debris  Orbit determination 

For several decades, orbital debris have been identified as a serious concern! This orbital debris potentially threatens future space missions, mainly in Low Earth Orbits and in Geostationary Earth Orbit, due to the risk of high energy collisions with valuable spacecraft. Orbital debris comprise the non-functional hardware orbiting the Earth, decommissioned spacecraft, spent upper stages, operational debris or residues from collisions; 94% of catalogued orbital objects are nowadays orbital debris. A complete presentation of the topic has been published with the year 2000 revision of the IAA Position Paper on Orbital Debris1. There are only very limited ways to improve the risks or effects of collisions: . Removal of large potential colliders does not seem practically feasible today, due to operational and programmatic constraints, . Collision avoidance is possible only with large catalogued debris, but requires access to precise orbital data for the largest debris, thanks to propagation of orbital tracks based on large observation facilities . Shielding of critical spacecraft is possible up to a low energy limit only: debris larger than 1 or 2 cm impacting an active spacecraft may have very deadly effect . Mitigation is by far the most efficient strategy: limiting the number of orbital debris in the critical orbital zones is the most efficient strategy for long term stability of the orbital population The study led by an ad-hoc group of specialists from the International Academy of Astronautics (IAA) under the leadership of Commission V, has established a number of clear recommendations aiming at promoting long term orbital debris mitigation. The study covered both the spacecraft and the launchers topics, through two independent subworking groups, whose findings are presented separately in this document. Their major recommendations are very similar: . There shall be no generation of operational debris: a space mission shall be clean, generating no long-term orbital debris such as clamp bands, fairings, optics protections, . There shall be no risk of explosion following end of mission: any spacecraft or upper stage left in orbit shall be 'passivated', i.e. its internal energy shall be eliminated: residual propellants shall be dumped, pressurants shall be depleted, batteries safed, etc. As per beginning of 2005, more than 180 in-orbit explosions have occurred, generating about 40% of the orbital debris population: it can easily be avoided. . Two orbital regions shall be protected, due to their economical importance: Low Earth Region, ranging up to 2000 km altitude, and Geostationary Earth Orbit. A clear motto has been identified as a long term strategy: there shall be no orbital debris creation within these two protected regions. As this recommendation may not sound realistic currently, it may be replaced in the coming decade by there shall be no long lived orbital debris creation within the two protected regions.

Source: Noordwijk: ESA Publication Division, 2006

Publisher: ESA Publication Division, Noordwijk, NLD