Design of High-Inclination Artificial Frozen Orbits Around Europa

High-inclination near-circular orbits are valuable for Europa’s global observation. However, the eccentricity drifts due to Jovian third-body gravity and Europa’s nonspherical gravity perturbations. Previous studies have concentrated on long lifetime orbits, but seldom maintained the orbits with low-thrust propulsion. In this work, we propose methods for designing near-circle and high-inclination artificial frozen orbits around Europa. The design method is separated into two parts. First, based on an analytical method, two frozen strategies are developed for maintaining the Europa probe, which use indirect and direct neutralization of the eccentricity drift, respectively. The analysis of the evolution characteristic of the artificial frozen orbit is presented. Second, through a semi-analytical approach, fuel-optimal low-thrust strategies which satisfy the proposed frozen strategies are derived to generate the artificial frozen orbits. Numerical simulations show that these artificial orbits have the ability of achieving the frozen behavior, with acceptable required velocity increments. The low-cost control strategies are also obtained.