威胁表征：轨迹动态
Threat Characterization: Trajectory Dynamics
摘要：
由于主要关心的是“减轻”撞击地球的近地天体的“潜在危险”，因此定性问题具有在将小行星视为抽象天体时通常不存在的一个方面。在考虑到改变小行星轨道以使其随后避免与地球撞击的物理挑战时，许多偏转概念都对小行星的典型地球物理特征感兴趣。然而，对于所有的偏转概念，威胁的特征都压倒了这些传统因素。例如，在撞击前几年或几十年与地球的近距离引力相遇，如果偏转先于近距离相遇（或相遇），则偏转所需的速度变化可以减少几个数量级。相反，这一“好处”是有“代价”的;确定撞击概率所需的跟踪准确性相应提高。国家和国际社会问题也是近地物体偏转过程的特点，这些问题可能与通常考虑的纯技术问题有很大的冲突。因此，必须考虑到通常不考虑的关键因素，因为这些因素是近地天体撞击威胁的特征。
英文摘要：
Given a primary interest in "mitigation of the potential hazard" of near-Earth objects impacting the Earth, the subject of characterization takes on an aspect not normally present when considering asteroids as abstract bodies. Many deflection concepts are interested in the classic geophysical characteristics of asteroids when considering the physical challenge of modifying their orbits in order to cause them to subsequently miss an impact with Earth. Yet for all deflection concepts there are characteristics of the threat which overwhelm these traditional factors. For example, a close gravitational encounter with Earth some years or decades prior to impact can reduce the velocity change necessary for deflection by several orders of magnitude if the deflection precedes the close encounter (or encounters). Conversely this "benefit" comes at a "price"; a corresponding increase in the accuracy of tracking required to determine the probability of impact. Societal issues, both national and international, also characterize the NEO deflection process and these may strongly contend with the purely technical issues normally considered. Therefore critical factors not normally considered must be brought into play as one characterizes the threat of NEO impacts.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
