Structural Selection in Macroscopic Orbital Systems: Admissible Trajectories Under Gravitational Constraint

Macroscopic orbital motion is traditionally described in terms of forces, initial conditions, and long-term dynamical evolution. While this framework successfully predicts trajectories, it often obscures why certain orbital configurations persist robustly under perturbation while others rapidly destabilize. In this work, we present a structure-first interpretation of orbital stability in which gravitational fields act as global constraints that select admissible trajectories prior to detailed dynamical evolution. We show that stable orbits correspond to structurally admissible corridors in phase space, while dissipation and perturbations suppress non-recoverable paths rather than generating orbital structure. This ordering preserves standard celestial mechanics while clarifying the origin of orbital robustness and long-term persistence. The framework provides a unified interpretive language for macroscopic orbital systems without invoking cosmological assumptions, temporal restructuring, or modifications to gravitational theory. Keywords: Structural selection, orbital stability, celestial mechanics, gravitational constraint, admissible trajectories, phase-space structure, perturbations and dissipation, orbital dynamics.