Potentially Hazardous Objects (PHOs) represent one of the most significant natural threats for Earth. Consequently, space agencies are expanding their planetary defense programs and investigating mission architectures capable of responding rapidly to late detections. Current planetary defense strategies rely on reactive missions that are fully designed only after a threat is discovered; such missions typically require 5-10 years from initial design to launch and operational readiness. This timeline is incompatible with late-warning scenarios, where discovery may occur only months or a few years before potential impact. To overcome this limitation, a promising architectural alternative consists of deploying a kinetic impactor on a suitable Earth–Moon orbit in advance. Such a spacecraft would remain in a long-term parking orbit, ready to perform a rapid escape as soon as a hazardous object is identified. The effectiveness of this concept depends on three major factors: (i) ability to depart the Earth-Moon system quickly and efficiently; (ii) station-keeping cost associated with the parking orbit; and (iii) fraction of the celestial sphere, or PHO population, that can be reached under realistic fuel and time constraints.

Within this context, the present work addresses the design, comparison and selection of candidate Earth-Moon parking orbits and the analysis and optimization of associated escape strategies. The goal is to identify the most suitable orbital configuration and escape architecture to support a pre-deployed kinetic impactor for planetary defense. Motion within the Earth–Moon system is described in the Circular Restricted Three-Body Problem (CR3BP), whereas the transition to heliocentric dynamics is introduced via patched conics at the Earth’s sphere of gravitational influence.

Previous contributions have largely focused on specific orbits, such as the Gateway 9:2 Near-Rectilinear Halo Orbit (NRHO), or few other solutions in the Heliocentric regime; these choices were justified by other mission needs or constraints. This paper aims at providing a comprehensive and systematic exploration of a variety of orbit families and escape strategies, specifically tailored for rapid asteroid interception , thus enhancing escape efficiency/costs and responsiveness, thereby strengthening the strategic value of an in-orbit interceptor.

The study begins by computing and analyzing several families of Earth-Moon periodic orbits using differential correction and pseudo-arclength continuation. These include resonant orbits, halo-type orbits, and previously unexplored families named Low-Energy Prograde Cycler Orbits, recently introduced in the literature. Each orbit is evaluated through a unified set of metrics: dynamical stability index, station-keeping cost, and escape opportunity frequency. This classification provides an immediate way to identify orbits that combine low operational maintenance with favorable natural escape channels, forming the foundation on which escape optimization is subsequently built.

The analysis of escape trajectories starts with classifying the feasible strategies and defining their optimization variables. Two strategies are investigated in detail: direct escape, consisting of a single impulsive maneuver applied at a selected phase of the periodic orbit and a two-impulse gravity-assisted escape, where an initial maneuver places the spacecraft on a trajectory that performs a close Earth flyby, during which a second impulse is applied to inject the spacecraft onto an escape trajectory aiming at the Earth’s sphere of gravitational influence with the desired heliocentric velocity. To support the optimization process, a preliminary grid search is carried out to explore the decision space and provide well-conditioned initial guesses for the ensuing nonlinear refinement.

Following detailed analysis of the different combinations of orbits and strategies, a comprehensive reachability study is conducted using real PHO datasets. For each object, the required escape conditions are compared with the maneuver derived from the optimized strategies. This enables an empirical assessment of which parking orbit and escape provides the best coverage and responsiveness for planetary defense.

Overall, the work presents an integrated orbital and escape-trajectory design for identifying viable Earth–Moon parking orbits and their corresponding departure paths for pre-deployed kinetic impactors. The results highlight trade-offs between stability, operational cost, escape performance, and population reachability, offering concrete guidance for future planetary defense architectures.