Effect of release conditions on casualty risk factor in uncontrolled re-entry of large space debris

Abstract

Abstract In this research, two existing re-entry models, the Debris Risk Assessment and Mitigation Analysis (DRAMA) model and the Debris Assessment Software (DAS) are used to study the influences of varying the parameters of the debris disposal orbit and its release conditions on the resultant casualty risk factor. With this perspective, the de-orbiting stage of an active debris removal (ADR) mission can be designed such that the parameters of the disposal orbit minimize the casualty risk of large debris re-entry, while maintaining feasible fuel and time constraints on the de-orbit manoeuvre. With respect to release conditions, the effect of introducing a small-magnitude impulse onto the debris at the release is studied, consequently showing that the casualty risk factor can be lowered even further. The change in the risk factor that results from an impulse is highly dependent on both the magnitude and the direction of the impulse with respect to the debris flight path. Furthermore, it has previously been demonstrated that the orientation and surface area of a piece of debris at the onset of re-entry have a significant impact on the characteristics of the re-entry. To this end, the coupled orbit-attitude propagator developed in our prior work, Debris SPin/Orbit Simulation Environment (D-SPOSE), is used to analyze the rotational state evolution of the debris between its release at ~ 200 km and the onset of re-entry assumed at ~ 125 km altitude. The debris is released with various attitude orientations, and the implications of the attitude state during descent on the DRAMA re-entry analysis are discussed.