Nicolò Trabacchin, University of Padova; Jan Siminski, ESA/ESOC; Lorenzo Olivieri, University of Padova
https://doi.org/10.64861/HKKM1877
Keywords: Cislunar, Tracking, Surveillance, Space Debris, Initial Orbit Determination
Abstract:
The cislunar region, the vast volume of space extending from GEO to the Moon and encompassing the Earth-Moon libration points, is rapidly emerging as a critical domain for scientific exploration and commercial expansion. Over the coming decades, missions sponsored by governmental agencies, commercial operators, and international partners are expected to populate lunar transfer trajectories, libration-point orbits, and lunar orbits with an increasingly diverse set of spacecraft. This raises concerns regarding orbital congestion, coordination complexity, and long-term collision risk. Unlike Low Earth Orbit, where decades of largely unregulated activity have produced a hazardous debris environment requiring costly mitigation, the cislunar domain still offers a rare strategic opportunity: deploying surveillance and tracking capabilities before congestion reaches critical levels.
To date, most research has concentrated on the detectability performance of candidate observatory architectures, emphasizing sensor coverage and sensitivity for the identification of resident space objects. A fundamental aspect remains comparatively underexplored: the effective trackability of space objects in the highly dynamic, weakly bound environment of the cislunar regime. This challenge is inherently more complex than its near-Earth counterpart. Two-body dynamics provide a well-conditioned framework for orbit determination in LEO; in the cislunar domain, third-body perturbations and the multi-body structure of the Earth-Moon system alter the problem fundamentally, producing strong sensitivity of trajectory propagation to initial-state uncertainties and non-uniqueness of initial orbit determination, since a common set of observations may be compatible with multiple candidate trajectories. The situation becomes more critical in contingency scenarios: the fragmentation of a single large spacecraft could disperse a debris cloud along unstable manifolds, populating vast regions of cislunar phase space.
To investigate this scenario, the present work develops an observatory architecture dedicated to tracking space objects in the cislunar domain, with the observer placed on an Earth-Moon orbit chosen for its favorable geometry and wide observational coverage. The tracked population is not derived from the NASA Standard Breakup Model, which relies on databases built from past events and simplified fragmentation assumptions. Instead, it is generated through the simulated fragmentation of an LRO-class satellite using the Collision Simulation Tool Solver, a semi-empirical tool developed at the University of Padova that represents complex spacecraft configurations at reasonable computational cost.
Building on this foundation, the work moves beyond detection to a systematic, population-level assessment of trackability. Observation windows and revisit opportunities are first evaluated for the proposed observatory geometry. A dedicated sensitivity analysis, built around the Fisher Information Matrix of each observed arc, is then used to identify the geometrical and temporal parameters that govern the suitability of the resulting data for initial orbit determination and to characterize the latency with which observation sets potentially conducive to orbit reconstruction become available.
Rather than proposing a prescriptive operational concept, the study offers a methodological framework for assessing cislunar trackability under realistic dynamical and observational constraints, moving the discussion from sensor detectability toward sustained, reliable tracking as the central enabling capability for future Cislunar Space Situational Awareness architectures.
Date of Conference: September 15-18, 2026
Track: Cislunar SDA