Study On Typical Applied Orbits Around Terrestrial Planets

Orbits around the center are preference to close and continuous observations to terrestrial planets. With the background of orbits around terrestrial planets, this thesis studies orbit perturbations, artificial orbits, the influence of perturbations on spacecraft formation configuration, and optimization of utility orbits.Firstly, orbits around terrestrial planets are investigated by using perturbation theory, and the major perturbations suffered by spacecraft orbiting Mercury, Venus, the Earth, and Mars are compared, respectively. By using analytical methods, the dynamics of several typical orbits around terrestrial planets are analyzed: Sun-synchronous orbit, the critical inclination orbit, and frozen orbit. The differences of key property between the utility orbits around terrestrial planets and the Earth are analyzed.For artificial orbits, the feasibility of using continuous lowthrust to arbitrarily design the orbital parameters of Sun-synchronous orbits, frozen orbits, and Sun-synchronous frozen orbits are studied. Considering the effects of main zonal harmonic terms(J2, J3, and J4) ofterrestrial planets' non-spherical gravitational potentials, the thrust and characteristic velocity of variety of control strategies are derived. The energy-saving control laws are designed for artificial Sun-synchronous orbits, frozen orbits, and Sun-synchronous frozen orbits. Simulations demonstrate the validity of the control strategies using continuous lowthrust.To study the influence of perturbations on spacecraft formation configuration, the relationship between the formation configuration parameters and the classic orbital elements is derived, and then, the effects of the first- and second-order secular perturbations due to non-spherical gravitational potential of terrestrial planets are analyzed. The control method through modifyingthe semi-major axis to reduce the effect is presented. As an example, spacecraft formations around Mercury, Venus, the Earth, and Mars are simulated and analyzed. Results show the effectiveness of this method.To optimize the utility orbits around terrestrial planets, the algorithm framework using the Multi-objective Evolutionary Algorithm Based on Decomposition(MOEA/D) is employed. Examples of orbits around Mars show that the algorithm framework is effective. To overcome the disadvantages of long-time estimation and high-cost search, Gaussian Process Modelling is used to assist to improve the algorithm framework.