Consideration of Space Debris Mitigation Requirements in the Operation of LEO Missions

Space debris is an emerging factor in the operation of spacecraft in the Low Earth Orbit regime (LEO) where some altitude bands are densely populated with man-made objects. The consequences are the perturbation of operations through frequent warnings and, casually, collision avoidance manoeuvres. ESA is operating three spacecraft in sunsynchronous orbits. Conjunctions have been monitored since 2004 and the process has been considerably improved and is now significantly assisted by the warning bulletins submitted by the Joint Space Operations Centre (JSpOC). The number of warnings to process and collision avoidance manoeuvres to perform is a function of the probability thresholds used in the various procedures and the object density which again depends on altitude. This paper addresses the number of warning events as a function of the operating altitude for LEO spacecraft. It demonstrates the experience made in ESA with their collision avoidance process and criteria.