近地小行星天地基光学监测系统预警能力分析

针对近地小行星撞击地球的威胁，分析研究了各类典型天地基光学监测系统的短期预警能力.提出了短期预警圈的概念，利用太阳系内天体光学反射模型，仿真计算了以LSST为代表的大口径地基望远镜，以日-地L1点、类金星轨道和大幅值逆行轨道三种典型轨道为代表的天基光学监测系统的短期预警能力，并比较了三种天基系统对太阳方向来袭的近地小行星的预警能力.结果表明，L1点预警覆盖稍好但可提供的预警时间较短；类金星轨道星座预警时间长、天区覆盖广，但存在相位间隙会导致漏警；大幅值逆行轨道针对太阳方向具有覆盖率高、预警时间长等优势.可见，通过部署若干天基系统监测节点，可以为地基监测系统提供有力补充，解决太阳方向的覆盖盲区问题，全方位预警近地小行星撞击地球风险. 

Analysis of Ground-Based and Space-Based Optical Observation System Warning Capability of Near-Earth Asteroids

In response to the threat of near-Earth asteroid impacts,the short-term warning capabilities of various typical ground-based and space-based optical observation systems for near-Earth asteroids (NEAs) were analyzed. The concept of short-term warning circle was proposed. Using the visible reflection model of celestial bodies in the solar system,the short-term warning capabilities of large-aperture ground-based telescope LSST,and three typical space-based telescopes deployed in the orbits of Sun-Earth L1 point,Venus-like orbit and distant retrograde orbit were simulated and calculated and the early warning capabilities of three space-based systems for NEAs approaching from the direction of the sun were compared. The results show that the early warning capability of L1 was good but the available warning time was short relatively; the Venus-like orbit constellation had a long warning time and wide coverage area,but the existence of phase gaps would cause a big omission probability; distant retrograde orbit had the advantages of high coverage rate and long warning time to the NEAs from the direction of the sun. The deployment of several space-based telescopes can provide sufficient supplement to the ground-based observation system,solve the problem of coverage omission in the direction of the sun,and provide approaching warning of NEAs in all directions.