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Projecte llegit

Títol: Design of a Hybrid Satellite Constellation for Lunar Communications and Navigation

Estudiants que han llegit aquest projecte:

Director/a: GUTIÉRREZ CABELLO, JORDI

Departament: FIS

Títol: Design of a Hybrid Satellite Constellation for Lunar Communications and Navigation

Data inici oferta: 04-02-2026     Data finalització oferta: 04-10-2026


Estudis d'assignació del projecte:
    GR ENG SIST AEROESP
Tipus: Individual
 
Lloc de realització: EETAC
 
Paraules clau:
Lunar Satellite Constellations, Multi-Objective Optimization,Astrodynamics,Space Navigation (PNT),Genetic Algorithms,Orbital Stability
 
Descripció del contingut i pla d'activitats:
As lunar exploration enters a transformative era, with the expected concurrency between China, and the US and Europe, the demand for a robust, high-availability communication infrastructure is paramount.

This Bachelor's Thesis explores the architecture of a hybrid satellite constellation designed to ensure seamless connectivity between Earth and the Moon, as well as among disparate lunar surface locations.

By integrating satellites across Low Lunar Orbit (LLO), Medium Lunar Orbit (MLO), and Earth-Moon Lagrange points, we will study the way to optimize coverage while rigorously accounting for the Moon's gravitational irregularities. The resulting design shall offer a scalable solution for continuous, high-bandwidth data relay in the challenging lunar orbital environment.
 
Overview (resum en anglès):
The renewed international interest in lunar exploration, driven by programmes such as NASA's Artemis, the Commercial Lunar Payload Services initiative and ESA's Moonlight, has created an urgent need for dedicated Positioning, Navigation and Timing (PNT) and communication infrastructure around the Moon. Unlike terrestrial Walker constellations, lunar satellite architectures cannot be designed through closed-form analytical rules. The Moon's highly non-uniform gravity field, driven by mass concentrations (mascons), together with strong third-body perturbations from the Earth and Sun and resonant instability mechanisms such as the Kozai-Lidov effect, render the orbital parameter space discontinuous and largely unpredictable, demanding high-fidelity numerical propagation and heuristic, population-based optimisation methods.

This work presents an integrated framework for the preliminary design of hybrid lunar communications and navigation constellations. The framework couples high-fidelity orbital propagation, implemented through TUDAT and the CEGM03 lunar gravity field, with the NSGA-II multi-objective genetic algorithm, implemented via pymoo. An offline, empirically validated stability-grid characterisation of the lunar Keplerian parameter space is used to filter the search efficiently, while the genetic algorithm searches jointly over coverage, navigation geometry (2D-HDOP and GDOP), Earth connectivity and annual station-keeping cost.

One of the central methodological contributions of this work is a hybrid-computed $\Delta$v metric that routes each candidate orbit to one of three estimation branches according to its dynamical regime: a doubly-averaged secular model for high, non-frozen orbits; an element-wise recovery-burn model derived directly from the propagated trajectory for low orbits; and a dedicated libration branch that replaces the otherwise tautological near-zero cost of near-frozen orbits with a physically meaningful, measured maintenance cost. This routing scheme is validated against the Moonlight Elliptical Lunar Frozen Orbit of Leonardi et al. and against the doubly-averaged station-keeping estimates of Tselousova.

The framework is applied to three case studies: a global lunar stability survey a communications-relay and navigation constellation optimised for dual-pole coverage. The results show that the optimiser autonomously rediscovers frozen-orbit solutions, that navigation performance improves systematically as the search space is progressively constrained towards dynamically favourable regions, and that communications and navigation objectives are largely complementary rather than antagonistic within the explored design space. A cross-validation against the published navigation study of Zanotti et al. confirms that the framework independently converges to the same optimal inclination band despite differences in optimiser, parametrisation and point-of-interest configuration, providing confidence in the overall methodology.

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