Crowding of the geostationary orbit

The number of likely collisions and disturbances suffered by an active geostationary satellite involving abandoned geosynchronous satellites and other active satellites in the same longitudinal slot is evaluated. While the risk of a collision with (and even of disturbances from) abandoned satellites is very remote, the risk of a collision and the number of likely disturbances during the lifetime of a satellite with other satellites operating in the same longitudinal slot could be unacceptably high, its value depending on stationkeeping strategies which, in turn, depend on mission constraints and satellite design. Provisions involving spacecraft and ground station equipment to reduce collision and disturbance risks are discussed. Algorithms to build a detailed model of the population of abandoned objects around the geostationary orbit are presented.