Orbital Dynamics and Stability of Near-Earth Asteroids

Near-Earth Asteroids (NEAs) represent a dynamically complex population of small Solar System bodies whose orbits are shaped by persistent gravitational interactions rather than static Keplerian motion. Understanding the orbital dynamics and stability of NEAs is essential both for reconstructing their origin and for assessing their long-term evolution and potential impact risk. This study presents a structured analysis of the dynamical framework governing NEA motion, emphasizing the roles of multi-body perturbations, planetary encounters, and resonant mechanisms. The orbital evolution of NEAs is shown to be strongly influenced by close gravitational encounters with terrestrial planets, which induce stochastic changes in orbital elements and limit long-term predictability. In parallel, mean-motion and secular resonances—particularly those associated with Jupiter and Saturn—act as efficient transport channels from the main asteroid belt into near-Earth space and drive systematic variations in eccentricity and inclination. The combined effects of resonant overlap and frequent planetary encounters render most NEA orbits intrinsically chaotic, leading to dynamical instability on timescales of millions of years. Numerical studies indicate that NEAs are transient members of the near-Earth region, with evolutionary pathways that include planetary collision, solar impact, or ejection from the inner Solar System. This work highlights the fundamental dynamical processes governing NEA stability and provides a coherent framework for interpreting their observed orbital distribution.