Orbital Dynamics Of High Area-to-mass Ratio Satellite And Analytic Method For Long-term Evolution

High area-to-mass ratio satellite aims to a kind of satellite which has a characteristic dimension of centimeter or millimeter and area-to-mass ratio larger than 1m2/kg.The chip satellite and smart dust belong to this kind of satellite.The dynamics of high area-to-mass satellite is inclined to environmental forces,thus its orbit and attitude are coupled,and the orbit drifts easily.The function of single high area-to-mass satellite is usually limited.To accomplish more complex missions,high area-to-mass satellites are usually performed in a constellation,cluster or swarm.For these reasons,this paper focus on the solutions of equilibrium orbits,research on dynamics and control of high area-to-mass satellite and long-term evolution of satellite constellation.In this way,the theory basis is found for high area-to-mass satellite applications.The thesis mainly researches on the high area-to-mass ratio satellite dynamics and orbit manuver,and long-term evolution of satellite constellation.We make intensive work on orbital characteristics at different heights,long-term evolution of constellation and orbit control method in orbit transfer.The main research results are as follows.Drag and solar radiation pressure,as functions of area-to-mass ratio,are main environmental forces for a HAMR satellite orbiting in LEO and MEO.Drag makes the energy of the orbital height decrease sharply.Energy gains from solar radiation pressure.It is propable to low down the descending rate of orbit radius by usage of solar radiation pressure.Thus,the trajectory can be stable due to the influence of central-body gravitation,drag and solar radiation pressure.For this reason,we model orbital dynamics of high area-to-mass satellite under J2 perturbation,drag and solar radiation pressure.Moreover,we present the equilibrium equations,which are solved by semi-analytical method.After that,the initial conditions satisfying the equilibrium orbits are given.We obtain the conclusion that the equilibrium orbits can be divided into two groups according to the relative positions of satellite,the Earth and the Sun.One is the equilibrium orbit with initial perigee lying between the Earth and the Sun.This kind of equilibrium orbits has maximum perigee and small initial eccentricity.At the same eccentricity,initial height grows with increasing area-to-mass ratios.Another is satellite perigee lying in the same side of the Earth and the Sun.This kind of equilibrium orbits has large eccentricity,and wide range of initial heights.Finally,the long-term evolutions under different initial conditions were presented.Simulations show the solutions of equilibrium equations enabling the long-lived and stable orbits by selecting five representive equilibrium orbits.The first kind of equilibrium orbits is proved to be stable in the simulation.A large number of high area-to-mass satellites in orbit flying in a formation will obtain enhanced coverage of the Earth and accomplish more applications.How to describe the status of constellation and establish the analysis method of long-term evolution of constellation under the effect of drag is a problem to be solved urgently.To research on the long-term evolution of high area-to-mass ratio satellite constellation,this paper propose constellation density as description of the behaviours of constellation.According the stable number of satellites in the constellation,constellation differential equations have been derived.As to the long-term evolution of equibrium orbital constellation,the problem has been translated into one-order Cauchy problem.Method of characteristic curves has been used to solve the problem,realizing quantitative expression of constellation.Under the assumption of initial uniform distribution,simulation has showed that when constellation is in equilibrium orbit,constellation at perigee and apogee will reach its minimum and maximum after half an orbital period,respectively.As to non-equibrium orbital constellation,constellation density will decrease evidently at low height under the influence of atmospheric drag.As time grew,the region coverd by the constellation enlarged,and the maximum of constellation density will decrease.There will be various applications and low risks in orbit if high area-to-mass ratio satellite has active control ability.If the high area-to-mass ratio satellite does not have an orbital thruster,the maneuver of satellite will be a problem that needs to be solved.To research the orbit transfer method of high area-to-mass satellite,the problem is translated into Lambert problem.An iteration method has been used to solve the problem.Quidance matrix is derived to enable the required transfer trajectory and the acceleration is calculated.According to the characters of high area-to-mass ratio satellite,the direction of satellite could be changed by attitude control.In this way,the force environment becomes different.Thus,the acceleration can be changed to the requied one.In the simulation of different scenarios with the satellite lying in the geocentric and heliocentric orbital planes,the velocity and position accuracy can be satisfied in the process of satellite self-propelled transfer.