Investigation of Debris Cloud Expansion Using Metric-Based Analysis

The continuous growth of the space debris population around the Earth is undermining the use of space as a resource, which is critical for several space-based services used in everyday life.The sustainability of space activities and the safety of operational satellites is threatened by the increasing number of in-orbit breakups occurring each year, caused by collisions and explosions of inactive spacecraft.Therefore, a fast assessment of the debris cloud produced after catastrophic events is crucial to provide information for tasks such as collision avoidance maneuvers, observation planning and short-term risk investigations.Moreover, long-term investigations can provide insights into the consequences of such events.In this work, novel metrics for the characterization of the expansion of a debris cloud throughout time are proposed.In the first phase, the formulation exploits the synthetic generation of fragmentations through the application of the NASA Standard Breakup Model and the propagation of the cloud for a given time interval using a density-based approach.The latter treats the debris cloud as a continuum, rather than employing a piece-by-piece formulation, speeding up the propagation process.The typical timescales of the evolution of the cloud are investigated, leveraging Ashenberg's formulation for the time of band formation and comparing it with numerical goodnessof-fit tests to assess its accuracy.The aim of the metrics is to compute at each snapshot the spread of the fragments, which enables to capture the phase of the cloud evolution and the dispersion of the cloud itself.This method allows to detach the characterization of the cloud from the density-based model, which yields a complete description of the evolution of the cloud at the expense of higher complexity.The metric was devised in the context of the Orbital Fragmentation rEconstruction tool for forensics Analysis (OFELIA), an ESA-funded project, where the characterization of the debris cloud through the metric is integrated into the full analysis of the breakup event to aid several operations such as sensor pointing for observation, fragmentation reconstruction and collision risk assessments.