TerraSAR-X Orbital Debris Assessment

This report presents the various aspects related to orbital debris collision avoidance for the TerraSAR-X spacecraft. After having introduced the orbital debris environment, the space catalog maintained by the American military was analyzed in terms of availability, completeness, update frequency and accuracy. The collision risk for TerraSAR-X was therefore assessed, taking into account the catalogued objects and several models currently used by the scientific and engineering communities around the world. The collision avoidance experience matured by other space projects and agencies was briefly reviewed and the implications of adopting conjunction assessment and avoidance maneuvers for the TerraSAR-X project were examined in terms of rationale, alert and maneuver frequency, ground sensors and flight dynamics software requirements, maneuver strategies and Delta-V. The investment and operational cost of an effective collision assessment and avoidance system should be weighted against the relative importance of the evaluated probability of collision with dangerous debris, of the order of 1/1000 during the nominal mission duration, and the level of collision risk reduction, approximately 10%, reasonably affordable with the existing technology and resources.