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CEAS EuroGNC 2026

Lunar Lander Variable-Mass Dynamics Modeling Considering Propellant Sloshing
Carl-Johann Winkler Research Assistant, Technische Universität Dresden, Chair of Flight Mechanics and Control, 01307 Dresden, Germany.
Paul Acquatella GNC Systems Engineer, European Space Agency, Guidance, Navigation & Control Section, 2201 AZ Noordwijk, The Netherlands.
Francesco Capolupo GNC Systems Engineer, European Space Agency, Guidance, Navigation & Control Section, 2201 AZ Noordwijk, The Netherlands.
Harald Pfifer Professor, Technische Universität Dresden, Chair of Flight Mechanics and Control, 01307 Dresden, Germany.
Abstract:
Precision landings on the lunar surface are essential for accessing scientifically valuable sites and enabling future lunar base operations. Achieving such accuracy demands high-fidelity representations of the spacecraft dynamics during early GNC development phases. This work addresses two major challenges in modeling lunar lander dynamics: 1) the accurate capturing of variable-mass dynamics due to rapid propellant consumption, and 2) the characterization of sloshing-induced perturbations, which are strongly dependent on the fill level and the lander's acceleration. Expanding upon a rigid body dynamical model, in this paper we derive a set of nonlinear equations of motion that incorporates both variable-mass effects and sloshing dynamics using a pendulum-based approximation parameterized for spherical tanks. The formulation is modular and scalable, allowing a straightforward integration of multiple tanks and propulsion systems. The model's validity is demonstrated through a simplified lunar lander scenario showing very close alignment with published data on sloshing mode characteristics.
Keywords: GNC Design; Lunar Lander; Variable Mass; Propellant Sloshing; Equations of Motion
 View PDF CEAS-GNC-2026-041 doi: 10.82124/CEAS-GNC-2026-041


Carl-Johann Winkler, Paul Acquatella, Francesco Capolupo, Harald Pfifer: Lunar Lander Variable-Mass Dynamics Modeling Considering Propellant Sloshing. Proceedings of the 2026 CEAS EuroGNC conference. Madrid, Spain. May 2026. doi: 10.82124/CEAS-GNC-2026-041.
BibTeX entry (UTF-8):

@Incollection{CEAS-GNC-2026-041,
    author = {Winkler, Carl-Johann and Acquatella, Paul and Capolupo, Francesco and Pfifer, Harald},
    title = {Lunar Lander Variable-Mass Dynamics Modeling Considering Propellant Sloshing},
    booktitle = {Proceedings of the 2026 {CEAS EuroGNC} conference},
    address = {Madrid, Spain},
    month = may,
    year = {2026},
    doi = {10.82124/CEAS-GNC-2026-041}
}