During their lifetime, the Near-Earth Asteroids (NEAs) suffer numerous close encounters (CE) with Earth, Mars and Venus. It has been demonstrated that gravitational interactions during close planetary encounters can alter an asteroid’s spin state, and hence, along with collisions, play a role in the rotational evolution of NEAs. The variation of the rotational angular momentum during the encounters can increase or decrease the rotation rate depending on the initial condition. In addition to the rotation rate, close encounters cause variation in the movement of precession and nutation of the asteroid. Using a numerical model that takes into account the spin-orbit coupling of a body with ellipsoidal shape, the subject of this study is to analyze the rotational motion (rotation, precession and nutation) of asteroids during CE with the Earth for different initial conditions. We computed the variation of the obliquity and the variation of spin period after the CE. We found significant change in obliquity and spin period only in cases with strong encounter, that is in cases that the impact parameter of the encounter (1.2 ≤ d ≤ 7 (Earth radii) and the relative velocity (v) are small. Our results also show that the variation of rotational motion due to the close encounter is capable of tumbling the axis of rotation and gravitational rupture may occur in a few cases.

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关于NEA与地球近距离接触期间的旋转运动

近地小行星（NEA）在其一生中遭受了与地球，火星和金星的多次近距离接触（CE）。已经证明，在近距离行星相遇期间的引力相互作用可以改变小行星的自旋状态，因此，与碰撞一起在NEA的旋转演化中起作用。遭遇期间旋转角动量的变化会根据初始条件增加或减少旋转速率。除了旋转速度外，近距离相遇还会引起小行星进动和章动运动的变化。使用一个考虑椭圆形物体的自旋轨道耦合的数值模型，本研究的主题是分析旋转运动（自转，在CE与地球之间的小行星的进动和章动状态下）。我们计算了CE后的倾角变化和自旋周期的变化。我们发现仅在遇到强烈的情况下，即遇到影响的参数（1.2≤ d  ≤7（地球半径）和相对速度（v）是小的。我们的结果还表明，由于紧密接触而引起的旋转运动变化能够使旋转轴翻滚，并且在某些情况下可能会发生重力破裂。