Hunter Morris, The Aerospace Corporation; Matthew Hejduk, The Aerospace Corporation; Lauri Newman, NASA
Keywords: conjunction assessment, risk aggregation
Abstract:
Issues with Satellite Collision Risk Aggregation
H.A. Morris and M.D. Hejduk, The Aerospace Corporation; L.K. Newman, NASA CARA
With the observed growth in the orbital population due to the deployment of large satellite constellations, there is a strong need for a credible measure of long-term satellite collision risk. One widespread and intuitive tool for this task is the so-called “aggregate Pc”, which is based on the Pc or “probability of collision” metric widely used in conjunction assessment. This approach, while possessing
many attractive qualities, has one major drawback: it is unlikely to accurately reflect the expected long-term frequency of collision. This is because the derivation of the Pc itself relies on a hidden assumption that is very unrealistic from a frequentist perspective. The Pc may be justifiable on Bayesian grounds, but a Bayesian probability can be potentially misleading in a long-term risk assessment context, where the natural interpretation is in terms of long-term frequencies. In light of this problem, several alternative methods of long-term risk assessment are explored, some of which show promise but none of which is entirely satisfactory for immediate deployment.
Date of Conference: September 16-19, 2025
Track: Conjunction/RPO