This study examines the impact of total solar irradiance on the orbital stability of a space probe executing one or more gravity assist maneuvers. Analytical models are developed to describe the dependence of photon flux pressure and solar wind influence on the probe's trajectory as a function of orbital radius. Numerical simulations of ballistic orbits incorporating gravity assists demonstrate that even minor perturbations induced by solar radiation can lead to significant deviations from nominal trajectories. The amplification of these deviations through gravity assists highlights the necessity of accounting for solar radiation effects in high-precision mission planning. The findings provide critical insights for the design and control of interplanetary missions, ensuring enhanced trajectory predictability and stability. © 2025 Elsevier B.V., All rights reserved.