Research On Impact Dynamics And Momentum Transfer Of Binary Asteroid System

Asteroids often encounter collisions when they are moving,either by celestial body or an artificial object.Asteroid binary system exists widely in solar system.In this paper,the affect and the motion state of ejecta around an asteroid binary system are studied.Firstly,the dynamic environment around the binary asteroid system is analyzed.The motion of ejecta and its influence on the momentum of the asteroids are discussed.By the method of numerical simulation,a phase diagram of the ejecta is obtained.This phase diagram shows a distinct structure.We also found that the objects produced by the impact may be a potential source of the objects which move around asteroids.Reasons of the structure in the diagram are analyzed.The main contents of this paper include:In the introduction,the main research progresses in the field of asteroid impact and defense are introduced.Kinetic impact,as the most feasible defense method in technology at present,has already been tested in some real exploration missions.In the processes of research in this field,researches on ejecta mainly focus on numerical integration of specific problems,but do not pay attention to the properties of the ejecta as a whole group.And we found that few researches studied the movement of ejecta of an asteroid binary system.The basic theories of the craters are introduced.Firstly,the physical process of an impact is introduced.The source of the change of momentum of the asteroid and the calculation method of a mass element from the impact crater is discussed.Then,the properties of ejecta are discussed in detail.Through analysis,it is shown that low-speed ejecta carries more mass and momentum.However,it’s easier for the low-speed ejecta to land back on the asteroids.Finally,a brief analysis is made on an impact on a single asteroid.The dynamic theory around the asteroid binary system is introduced.The dynamic model is established and the stability of the asteroid binary system is discussed.It is explained that the angular velocity of revolution of the asteroid binary system is not arbitrary.It must satisfy some conditions which is up to the asteroid binary system.Normalization of the motion equation is carried out and the calculation method of the Jacobi constant is introduced.The calculation method of special functions is discussed.Finally,the research work of the evolution of an asteroid binary system in the vicinity of large celestial bodies is introduced.The Jacobi constant is used to make an in-depth study of the specific asteroid binary system,which is revealing the movement restrictions of the Jacobi constant on ejecta.We classified the ejecta based on its different initial states,which is related to the phase diagram which is discussed in the following paper.The method and strategy of selecting impact point in an impact mission are discussed.The motion state of ejecta is discussed in detail.The Jacobi constant and phase diagram are used to classify ejecta.By the method of numerical simulation,the effects of different types of ejecta on the momentum of asteroids are calculated.It is further clarified that it is very important to study the motion state of ejecta.Otherwise,an asteroid deflection mission may fail to achieve the expected effect.The phase diagram is used to analyze the motion state of ejecta.Special structures appear in the phase diagram usually,which can classify ejecta and analyze the causes.With the help of numerical simulation,the dynamic reasons of the structures in phase diagram are analyzed.The different structures of the asteroid binary system are discussed in details.We regard the diagram as 7 types.Based on the shape and dynamic environment,we can determine the type of orbits.We discuss the method of how to obtain the motion characteristics of ejecta from the phase diagram structure by combining the information of the impact point and the asteroid binary system is described.Also,the influences of the shape of the asteroid binary system on the phase diagram structure are discussed.The innovations of this paper include:1、The dynamic environment around a binary asteroid system is studied.The strategy of impact is analyzed.2、The characteristic of the momentum which is taken by ejecta is studied.Also,some special ejecta orbits are found.3、We put forward the method of analyzing the properties of ejecta.We studied the reasons for the formation of special structures in the phase diagram.We discussed the method of judging the type of the ejecta orbit.