The JUICE Lunar-Earth gravity assist from trajectory design, navigation and spacecraft operations perspective

Abstract. This paper describes the world’s first-ever Lunar–Earth Gravity Assist (LEGA) performed by ESA’s JUICE spacecraft on 19–20 August 2024 from trajectory design, navigation and spacecraft operations point of view.

This double flyby – Moon first, Earth second – enabled a large Delta-V gain while minimizing propellant use, redirecting JUICE toward its next destination: Venus (August 2025) and ultimately Jupiter (2031). The manoeuvre was unprecedented in complexity, requiring extremely accurate navigation, rigorous preparation, and coordinated operations across engineering, flight dynamics, and science teams.

Overall, JUICE demonstrated outstanding platform stability, navigation accuracy, and subsystem robustness during this critical milestone, validating the operational feasibility of LEGA as an enabling technique for complex interplanetary trajectories.

This paper is an executive summary of papers published on LEGA trajectory design [Schoenmaekers et al. (2014); Boutonnet et al. (2023)], navigation [Syndercombe et al. (2025)] and spacecraft operations [Heck et al. (2025)].