Dynamics of Small Celestial Body and Orbit Design Under Low Thrust Spacecraft

Small celestial bodies (SCB) including Near-Earth asteroids (NEA), as potentially dangerous that threaten the security of Earth and humankind, have now attracted attention of major spacefaring nations. Exploration of SCB is not only an important means to implement planetary defense, but also to obtain more valuable space resources and information. In China’s deep space detection program, 10 NEA are initially selected as potential targets. In this paper, orbit dynamics of the 10 asteroids are analyzed, and 2019VL5 is selected as an example to design and optimize the orbit of spacecraft under low thrust propulsion. First, a combined system with polar coordinates and orbit parameters are proposed to construct a spatial dynamic model for spacecraft motion, and initial conditions of geocentric transfer orbit are searched by the shape method. For the complex orbit optimization, continuous low thrust problem is formulated based on Pontryagin’s principle with dynamic model, and particle swarm optimization (PSO) algorithm accordingly with the improved Newton’s iteration method is applied to determine the initial values of energy-optimized covariance variable, then the fuel optimal orbit of heliocentric transfer of spacecraft is obtained by homotopic iteration. This method could provide a solution for the defense detection of small celestial bodies, as well as for the rapid determination of orbit design and optimization of spacecraft under low thrust.