Practical deep-space geocentric and out-of-ecliptic orbits in the sun-earth restricted three-body problem

This paper presents new families of geocentric orbits in the Sun-Earth spatial elliptic three-body problem (ER3BP) useful for deep space science missions such as planet finding and characterization. The main driver for this study is the need to find practical geocentric orbits that remain within a bounded distance from Earth, thus allowing high data-rate communication while ensuring safe operational environment far from thermal perturbations and visual occultations as well as Earth's magnetic and radiation fields, yet free of the stability and stationkeeping concerns associated with libration point missions or Halo orbits. The orbit characterization procedure is performed using a novel approach. Optimal initial conditions are found using niching genetic algorithms, which render global optimization while permitting several optimal or sub-optimal solutions to co-exist. This approach yields diverse families of orbits, both planar and three-dimensional, including out-of-ecliptic orbits that greatly reduce the impact of the local zodiacal cloud. Stability of the orbits is determined using the notion of practical stability. The effect of solar radiation pressure and the Moon's gravitational perturbation are simulated, showing that the orbits are not significantly affected. This feature implies that no station-keeping is required. Optimal direct transfer trajectories from Low Earth orbit are briefly presented, showing that insertion into the characterized orbits may be performed using modest energetic requirements.