威胁小天体动能撞击防御误差演化分析

Uncertainty Propagation of Kinetic Impact on Dangerous Small Celestial Bodies

部分近地小天体存在撞击地球的潜在风险,利用航天器动能撞击小天体实现轨道偏转是目前较为成熟的小天体防御方案,但在动能撞击过程中,撞击器的制导控制误差可能造成实际撞击小行星的位置与预定撞击位置的差异,进而造成小行星撞击后的速度改变量偏差,影响小行星防御任务的效果。为了定量地分析这种误差带来的影响,本文开展了小天体动能撞击误差演化分析研究。首先基于斜撞击模型,分析了撞击位置偏差对撞击后小行星速度增量变化的影响,然后利用状态转移张量(STT)分析了小行星从动能撞击后到其到达地球影响球时的状态误差演化情况,最后得出小行星到达地球附近时的终端位置速度散布情况。本文以动能撞击小行星Apophis为例进行仿真,结果表明在撞击制导位置误差3σ边界为15 m时,动能撞击5年后小行星到达地球近心点时的位置误差散布在10 km量级。

Some near-Earth small celestial bodies have the potential risk of colliding with Earth,and using spacecraft kinetic energy to impact small celestial bodies to achieve orbital deflection is currently a relatively mature defense plan for small celestial bodies.However,during the kinetic impact process,the guidance and control error of the impactor may cause a difference between the actual impact position of the asteroid and the predetermined impact position,resulting in a deviation in the velocity change after the asteroid impact,which affects the effectiveness of the asteroid defense mission.In order to quantitatively analyze the impact of this error,this paper conducted a study on the evolution of kinetic impact errors in small celestial bodies.Firstly,an oblique impact model was constructed based on impact geometry to describe the impact position of the impactor on an asteroid.The impact position deviation was analyzed to determine the impact velocity increment after impact.Then,the state transfer tensor(STT)method was used to analyze the evolution of the state error of the asteroid from kinetic impact to its arrival at the Earth sphere of influence.Finally,the dispersion of the terminal position velocity of the asteroid when it reaches the terminal near Earth is determined.The simulation results of this article indicate that this method can effectively predict the terminal state of small celestial bodies approaching the Earth.Taking the kinetic impact on the asteroid Apophis as an example,the simulation results show that the impact guidance position error is 3σwhen the boundary is 15m,the position error of the asteroid when it reaches the Earth’s perigee after 5 years of kinetic impact is scattered on the order of 10km.