Critical Conjunction Detection and Mitigation

Kurzfassung

Criteria for the critical conjunction are discussed. In the current collision avoidance operation, the collision probability is a key parameter for the criticality assessment of the detected conjunction to decide an avoidance maneuver. The conventional probability threshold of ~10-4 has been applied for LEO conjunctions at the German Space Operations Center. However, not all conjunctions can be decided only by this criterion due to the large variation of the orbit uncertainties estimated for the numerous space objects. To evaluate the effect of this characteristic, the collision probability and the avoided risk for the probability threshold were formulated using the standard deviations related to the covariance ellipse projected onto the B-plane, which is perpendicular to the relative velocity. The encountering objects of the past conjunctions were also categorized by the same parameter. The avoidable conjunction was then evaluated in terms of the operational aspects. Finally, the collision risk as a result of the collision avoidance operation was assessed.