The lunar probe often has some remaining fuel on completing the predefined Moon exploration mission and may carry out some additional tasks from the Moon orbit using the fuel.The possibility for the lunar probe to esc...The lunar probe often has some remaining fuel on completing the predefined Moon exploration mission and may carry out some additional tasks from the Moon orbit using the fuel.The possibility for the lunar probe to escape from the Moon and the Earth is analyzed.Design and optimization of the trajectory from the Moon orbit to the Near Earth Asteroids (NEAs) using the spacecraft's residual fuel is studied.At first,the semi-major axis,inclinations and the phase relations with the Earth of all the numbered NEAs are investigated to preliminarily select the possible targets.Based on the Sun-centered two-body problem,the launch window and the asteroid candidates are determined by calculating the minimum delta-v for two-impulse rendezvous mission and one-impulse flyby mission,respectively.For a precise designed trajectory,a full ephemeris dynamical model,which includes gravities of the Sun,the planets and the Moon,is adopted by reading the JPL ephemeris.The departure time,arrival time,burning time duration and thrust angles are set as variables to be designed and optimized.The optimization problem is solved via the Particle Swarm Optimization (PSO) algorithm.Moreover,two feasible NEA flyby missions are presented.展开更多
The motion of a surface vehicle on/above an irregular object is inv.estigated for a potential interest in the insitu explorations to asteroids of the solar system. A global valid numeric method, including detailed gra...The motion of a surface vehicle on/above an irregular object is inv.estigated for a potential interest in the insitu explorations to asteroids of the solar system. A global valid numeric method, including detailed gravity and geo- morphology, is developed to mimic the behaviors of the test particles governed by the orbital equations and surface cou- pling effects. A general discussion on the surface mechanical environment of a specified asteroid, 1620 Geographos, is presented to make a global evaluation of the surface vehicle's working conditions. We show the connections between the natural trajectories near the ground and differential features of the asteroid surface, which describes both the good and bad of typical terrains from the viewpoint of vehicles' dynamic performances. Monte Carlo simulations are performed to take a further look at the trajectories of particles initializing near the surface. The simulations reveal consistent conclusions with the analysis, i.e., the open- field flat ground and slightly concave basins/valleys are the best choices for the vehicles' dynamical security. The dependence of decending trajectories on the releasing height is studied as an application; the results show that the pole direction (where the centrifugal force is zero) is the most stable direction in which the shift of a natural trajectory will be well limited after landing. We present this work as an example for pre-analysis that provides guidance to engineering design of the exploration site and routing the surface vehicles.展开更多
The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.Thi...The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.This allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen 2.We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission.By comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos. 10832004 and 11072122)
文摘The lunar probe often has some remaining fuel on completing the predefined Moon exploration mission and may carry out some additional tasks from the Moon orbit using the fuel.The possibility for the lunar probe to escape from the Moon and the Earth is analyzed.Design and optimization of the trajectory from the Moon orbit to the Near Earth Asteroids (NEAs) using the spacecraft's residual fuel is studied.At first,the semi-major axis,inclinations and the phase relations with the Earth of all the numbered NEAs are investigated to preliminarily select the possible targets.Based on the Sun-centered two-body problem,the launch window and the asteroid candidates are determined by calculating the minimum delta-v for two-impulse rendezvous mission and one-impulse flyby mission,respectively.For a precise designed trajectory,a full ephemeris dynamical model,which includes gravities of the Sun,the planets and the Moon,is adopted by reading the JPL ephemeris.The departure time,arrival time,burning time duration and thrust angles are set as variables to be designed and optimized.The optimization problem is solved via the Particle Swarm Optimization (PSO) algorithm.Moreover,two feasible NEA flyby missions are presented.
基金supported by the National Basic Research Program of China(973 Program)(2012CB720000)the National Natural Science Foundation of China(11372150)
文摘The motion of a surface vehicle on/above an irregular object is inv.estigated for a potential interest in the insitu explorations to asteroids of the solar system. A global valid numeric method, including detailed gravity and geo- morphology, is developed to mimic the behaviors of the test particles governed by the orbital equations and surface cou- pling effects. A general discussion on the surface mechanical environment of a specified asteroid, 1620 Geographos, is presented to make a global evaluation of the surface vehicle's working conditions. We show the connections between the natural trajectories near the ground and differential features of the asteroid surface, which describes both the good and bad of typical terrains from the viewpoint of vehicles' dynamic performances. Monte Carlo simulations are performed to take a further look at the trajectories of particles initializing near the surface. The simulations reveal consistent conclusions with the analysis, i.e., the open- field flat ground and slightly concave basins/valleys are the best choices for the vehicles' dynamical security. The dependence of decending trajectories on the releasing height is studied as an application; the results show that the pole direction (where the centrifugal force is zero) is the most stable direction in which the shift of a natural trajectory will be well limited after landing. We present this work as an example for pre-analysis that provides guidance to engineering design of the exploration site and routing the surface vehicles.
文摘The characteristics of asteroids are vital parameters for planning asteroid exploration missions.These characteristics have been explored in close range for some typical asteroids,and are summarized in the article.This allows estimates of the characteristics of asteroid 2016HO_(3),the target of the first Chinese asteroid exploration mission,Tianwen 2.We obtain 80 characteristic parameters in 9 categories and analyze their impacts on the mission.By comparing three close-range exploration modes,we provide advantages and disadvantages of each,and propose suitable methods for the exploration of 2016HO_(3).Owing to the weak gravity and small size of 2016HO_(3),a combination of multiple hovering positions and active orbiting is recommended for scientific exploration.