aerospace Article Results of Long-Duration Simulation of Distant Retrograde Orbits Gary Turner Odyssey Space Research, 1120 NASA Pkwy, Houston, TX 77058, USA;
[email protected] Academic Editor: Konstantinos Kontis Received: 31 July 2016; Accepted: 26 October 2016; Published: 8 November 2016 Abstract: Distant Retrograde Orbits in the Earth–Moon system are gaining in popularity as stable “parking” orbits for various conceptual missions. To investigate the stability of potential Distant Retrograde Orbits, simulations were executed, with propagation running over a thirty-year period. Initial conditions for the vehicle state were limited such that the position and velocity vectors were in the Earth–Moon orbital plane, with the velocity oriented such that it would produce retrograde motion about Moon. The resulting trajectories were investigated for stability in an environment that included the eccentric motion of Moon, non-spherical gravity of Earth and Moon, gravitational perturbations from Sun, Jupiter, and Venus, and the effects of radiation pressure. The results indicate that stability may be enhanced at certain resonant states within the Earth–Moon system. Keywords: Distant Retrograde Orbit; DRO; orbits-stability; radiation pressure; orbits-resonance; dynamics 1. Introduction 1.1. Overview The term Distant Retrograde Orbit (DRO) was introduced by O’Campo and Rosborough [1] to describe a set of trajectories that appeared to orbit the Earth–Moon system in a retrograde sense when compared with the motion of the Earth/Moon around the solar-system barycenter. It has since been extended to be a generic term applied to the motion of a minor body around the three-body system-barycenter where such motion gives the appearance of retrograde motion about the secondary body in the system.