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Recent works demonstrated that the dynamics caused by the planetary oblateness coupled with the solar radiation pressure can be described through a model based on singly averaged equations of motion. The coupled perturbations affect the evolution of the eccentricity, inclination and orientation of the orbit with respect to the Sun–Earth line. Resonant interactions lead to non-trivial orbital evolution that can be exploited in mission design. Moreover, the dynamics in the vicinity of each resonance can be analytically described by a resonant model that provides the location of the central and hyperbolic invariant manifolds which drive the phase space evolution. The classical tools of the dynamical systems theory can be applied to perform a preliminary mission analysis for practical applications. On this basis, in this work we provide a detailed derivation of the resonant dynamics, also in non-singular variables, and discuss its properties, by studying the main bifurcation phenomena associated with each resonance. Last, the analytical model will provide a simple analytical expression to obtain the area-to-mass ratio required for a satellite to deorbit from a given altitude in a feasible timescale. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this work is to compute transfer trajectories from a given Low Earth Orbit (LEO) to a nominal Lissajous quasi-periodic orbit either around the point L 1 or the point L 2 in the Earth–Moon system. This is achieved by adopting the Circular Restricted Three-Body Problem (CR3BP) as force model and applying the tools of Dynamical Systems Theory. It is known that the CR3BP admits five equilibrium points, also called Lagrangian points, and a first integral of motion, the Jacobi integral. In the neighbourhood of the equilibrium points L 1 and L 2, there exist periodic and quasi-periodic orbits and hyperbolic invariant manifolds which emanate from them. In this work, we focus on quasi-periodic Lissajous orbits and on the corresponding stable invariant manifolds. The transfers under study are established on two manoeuvres: the first one is required to leave the LEO, the second one to get either into the Lissajous orbit or into its associated stable manifold. We exploit order 25 Lindstedt–Poincaré series expansions to compute invariant objects, classical manoeuvres and differential correction procedures to build the whole transfer. If part of the trajectory lays on the stable manifold, it turns out that the transfer’s total cost, , and time, , depend mainly on: [1.] the altitude of the LEO; [2.] the geometry of the arrival orbit; [3.] the point of insertion into the stable manifold; [4.] the angle between the velocity of insertion on the manifold and the velocity on it. As example, for LEOs 360km high and Lissajous orbits of about 6000km wide, we obtain . As further finding, when the amplitude of the target orbit is large enough, there exist points for which it is more convenient to transfer from the LEO directly to the Lissajous orbit, that is, without inserting into its stable invariant manifold. [Copyright &y& Elsevier]

This contribution investigates the properties of a category of orbits around Enceladus. The motivation is the interest in the in situ exploration of this moon following Cassini's detection of plumes of water and organic compounds close to its south pole. In a previous investigation, a set of heteroclinic connections were designed between halo orbits around the equilibrium points L 1 and L 2 of the circular restricted three-body problem with Saturn and Enceladus as primaries. The kinematical and geometrical characteristics of those trajectories makes them good candidates as science orbits for the extended observation of the surface of Enceladus: they are highly inclined, they approach the moon and they are maneuver-free. However, the low heights above the surface and the strong perturbing effect of Saturn impose a more careful look at their dynamics, in particular regarding the influence of the polar flattening of the primaries. Therefore, those solutions are here reconsidered by employing a dynamical model that includes the effect of the oblateness of Saturn and Enceladus, individually and in combination. The dynamical equivalents of the halo orbits around the equilibrium points L 1 and L 2 and their stable and unstable hyperbolic invariant manifolds are obtained in the perturbed models, and maneuver-free heteroclinic connections are identified in the new framework. A systematic comparison with the corresponding solutions of the unperturbed problem shows that qualitative and quantitative features are not significantly altered when the oblateness of the primaries is taken into account. Furthermore, it is found that the J 2 coefficient of Saturn plays a larger role than that of Enceladus. From a mission perspective, the results confirm the scientific value of the solutions obtained in the classical circular restricted three-body problem and suggests that this simpler model can be used in a preliminary feasibility analysis. • Orbits in the Saturn–Enceladus three-body problem with oblate primaries are computed. • Heteroclinic connections between libration point orbits around Enceladus are designed. • Performance of heteroclinics as science orbits is assessed. • Solutions offer long, uninterrupted views of lunar surface at low speeds. • Solutions confirm previous results in classical circular restricted three-body problem. [ABSTRACT FROM AUTHOR]