Evaluation of minimum coverage size and orbital accuracy at different orbital regimes for one order of magnitude reduction of the catastrophic collision risk

• Published in: Advances in space research 2015-03, Vol.55 (6), p.1673-1686
• Main Authors: Sánchez-Ortiz, Noelia, Domínguez-González, Raúl, Krag, Holger
• Format: Article
• Language: English
• Subjects: Accuracy; Catalogue coverage; Catastrophic collision risk; Collision avoidance; Collision dynamics; Mathematical models; Orbital accuracy; Orbitals; Orbits; Reduction; Risk; Space debris; Space situational awareness; Space Surveillance and Tracking
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2014.12.034

•Statistical catastrophic collision risk along mission lifetime is assessed.•Catalogue coverage and accuracy are suggested for reliable conjunction assessment.•Evaluation of required performance for different orbital regimes is presented. One of the main objectives of Space Surveillance and Tracking (SST) systems is to support space collision avoidance activities. This collision avoidance capability aims to significantly reduce the catastrophic collision risk of space objects. In particular, for the case of the future European SST, the objective is translated into a risk reduction of one order of magnitude whilst keeping a low number of false alarm events. In order to translate this aim into system requirements, an evaluation of the current catastrophic collision risk for different orbital regimes is addressed. The reduction of such risk depends on the amount of catalogued objects (coverage) and the knowledge of the associated orbits in the catalogue (accuracy). This paper presents an analysis of the impact of those two aspects in the capability to reduce the catastrophic collision risk at some orbital regimes. A reliable collision avoidance support depends on the accuracy of the predicted miss-events. The assessment of possible conjunctions is normally done by computing the estimated miss-distances between objects (which is compared with a defined distance threshold) or by computing the associated collision risk (which is compared with the corresponding accepted collision probability level). This second method is normally recommended because it takes into account the reliability of the orbits and allows reducing false alarm events. The collision risk depends on the estimated miss-distance, the object sizes and the accuracy of the two orbits at the time of event. This accuracy depends on the error of the orbits at the orbit determination epoch and the error derived from the propagation from that epoch up to the time of event. The modified DRAMA ARES (Domínguez-González et al., 2012, 2013a,b; Gelhaus et al., 2014) provides information on the expected number of encounters for a given mission and year. It also provides information on the capacity to reduce the risk of collision by means of avoidance manoeuvres as a function of the accepted collision probability level and the cataloguing performance of the surveillance system (determined by the limiting coverage size-altitude function and the orbital data accuracy). The assessment of avoidance strategies takes