Nicolò Trabacchin, University of Padova; Giorgio Faggian, University of Padova; Valerio Pavan, University of Padova; Lorenzo Olivieri, University of Padova; Giacomo Colombatti, University of Padova
https://doi.org/10.64861/PJBC3167
Keywords: Space Debris, Cislunar Space, Fragmentation, Explosion, NRHO, ELFO
Abstract:
The cislunar domain is expected to undergo unprecedented growth in operational activity over the next decade, driven by governmental and private investments and by programs such as NASA’s Artemis architecture. Although the region is not yet congested, early indicators of operational risk have emerged: collision avoidance maneuvers have been performed in low lunar orbit and multiple conjunction alerts recorded. Fragmentation events can therefore no longer be considered implausible.
Without atmospheric drag, and given the multi-body dynamics of the Earth-Moon system, debris generated in lunar or cislunar orbits may persist for years and spread across dynamically connected regions. The nonlinear structures governing this regime challenge the predictive capability of traditional Earth-based models, making high-fidelity simulations of synthetic fragmentation populations essential to assess the severity and environmental consequences of a breakup, and to support Space Situational Awareness and future mitigation policies.
Most fragmentation studies still rely on the NASA Standard Breakup Model, whose fragment populations depend primarily on the masses of the involved bodies, derive from dated datasets, and do not explicitly account for modern spacecraft materials. The present work instead employs the Collision Simulation Tool Solver (CSTS), a semi-empirical breakup software developed at the University of Padova, which models complex geometries and heterogeneous materials and yields statistically robust fragment populations at limited computational cost.
As a representative case study, the explosion of a large spacecraft based on the Lunar Reconnaissance Orbiter design is simulated. Severity is characterized through the resulting distributions of characteristic length, area-to-mass ratio, and ejection velocity, which provide the initial conditions for dynamical propagation. Two orbital regimes of strategic relevance are considered: the 9:2 Near Rectilinear Halo Orbit selected for the Lunar Gateway, and Elliptical Lunar Frozen Orbits, of interest for future lunar PNT constellations.
The debris population is released from multiple points along each parent orbit to capture the influence of orbital phase and geometry, and propagated over 30-day and 1-year horizons with both the Circular Restricted Three-Body Problem and a full-ephemeris model, assessing the reliability of the simplified dynamics.
Results address fragment dispersion, residence time, and escape probability, with dynamically meaningful shells introduced around the Moon to classify debris residence and transit behavior, and quantify lunar surface impact risk through impact probability heat maps and temporal decay analyses. These analyses identify preferential impact zones and potential threats to future settlements.
The study delivers actionable parameters for risk assessment, inputs to mitigation policy discussions, and long-term sustainability planning in cislunar space.
Date of Conference: September 15-18, 2026
Track: Space Debris