Lorenzo Olivieri, DII/CISAS, University of Padova; Francesco Fabri, CISAS; Alberto Abiti, CISAS; Nicolò Trabacchin, CISAS; Cinzia Giacomuzzo, CISAS; Alessandro Francesconi, DII/CISAS, University of Padova
https://doi.org/10.64861/RJYD7039
Keywords: Space Debris, Synthetic Population, Collisions, Explosions, Simulations
Abstract:
The rapid expansion of human activities in Near-Earth space is leading to the degradation of the orbital environment, congested with both operational satellites and a vast number of debris. This latter population includes spent rocket stages, defunct satellites, and fragments from past break-up events, down to sub-millimetric debris. It represents a critical hazard to the safety of current and future missions, as even millimetre-sized objects traveling at hypervelocity possess sufficient kinetic energy to disable or destroy critical spacecraft components. As the space sector enters an era characterized by the deployment of large satellite constellations and a significant increase in launch frequencies, the ability to accurately characterize and predict the state of the orbital debris environment has become a central need for mission design, operational safety, and the definition of sustainable policies and practices. Observation systems, such as radar and optical sensors, provide indispensable data for maintaining public catalogues of tracked objects; however, they are intrinsically limited by detection thresholds, temporal gaps, and spatial coverage constraints. These limitations are particularly acute for small-scale debris, which remain largely invisible to current sensors yet contribute most significantly to the cumulative collision risk due to their high spatial density. In this context, the generation of synthetic space debris can overcome such limitations, as such populations can be employed both for short-term and long-term predictions of the consequences of fragmentation events. First, they can provide statistically accurate information on the potential propagation of the fragments generated by recent breakups, allowing both preventive manoeuvring and optimal observational scheduling. Second, they allow long-term modelling of the debris environment, giving scientists the tools to simulate the effects of different fragmentation events and enabling scenario-based analyses that explore how different technological, operational, and regulatory choices may influence the evolution of the debris environment over decades. Critical questions concerning the prevention of runaway collision cascades, often referred to as the Kessler Syndrome, or the long-term viability of specific orbital shells can be clearly supported by the representation provided by synthetic populations. The generation of reliable synthetic populations depends fundamentally on the robustness of the modelling tools employed. In this regard, the Collision Simulation Tool Solver (CSTS), developed at the Center of Studies and Activities for Space (CISAS) “G. Colombo” of the University of Padova in the framework of contracts with the European Space Agency and the Italian Space Agency, represents a sophisticated solution. This tool allows modelling a large variety of collision and explosion scenarios involving complex systems, such as entire satellites with many design details included, providing statistically accurate results with a computational effort orders of magnitude lower than hydrocodes. The software is based on a hybrid modelling strategy, in which complex bodies are described as a net of Macroscopic Elements (ME) representing spacecraft elementary building blocks. On one hand, the fragmentation of the Macroscopic Elements is addressed through the use of semi-empirical breakup models applied, at element level, only to those spacecraft parts which are involved in the collision. On the other hand, structural distortion, fracture, and separation of satellite broken parts are modelled with a discrete-element approach through the simulation of momentum transfer to the Macroscopic Elements through the net, taking into account energy dissipation inside elements and across links. Through this combined modelling scheme, CSTS simulations can reproduce the overall fragmentation process in detail providing the population of generated fragments and detached elements, with full knowledge of their geometrical and mass properties and of their relative velocity. CSTS has been validated by comparing the tool predictions with empirical data from ground-based impact tests on simple targets as well as sub-scale spacecraft models, showing a consistent agreement with the experiments. In addition, it has been employed to replicate different in-space break-ups, including the COSMOS 1408 anti-satellite test, the explosion of INTELSAT 33E, and the COSMOS 2251 – IRIDIUM 33 collision. In this work the generation of dedicated populations of event-related space debris populations is shown, and their potential utilization is described with simple use cases. In particular, synthetic populations are already available for a representative medium-sized observation satellite, for a rocket stage subjected to explosions, and for an exploding GEO telecommunication satellite. In addition, reference populations have been generated for spacecraft in the Cislunar environment as a testing ground for the evaluation of potential environmental scenarios. This simulation approach allows to generate in advance ready-to-use synthetic debris populations, supporting real-time assessment and response in the event of similar future fragmentations.
Date of Conference: September 15-18, 2026
Track: Space Debris