威胁缓解：重力拖拉机
Threat Mitigation: The Gravity Tractor
摘要：
重力牵引器（GT）是一个完全受控的小行星偏转概念，利用机器人航天器和小行星之间的相互引力，使小行星朝着“悬停”航天器的方向缓慢加速。根据地面跟踪和轨道预测提供的早期预警，它将在潜在撞击发生前十年或更长时间部署。离子发动机将用于与小行星会合和牵引阶段。由于GT在偏转过程中不与小行星对接或以其他方式进行物理接触，因此不需要了解小行星的形状、组成、旋转状态或其他“常规”特征。GT将首先通过地球跟踪其无线电应答器来减少小行星轨道的不确定性，同时与小行星保持站位。如果在对更精确的小行星轨道进行分析后确实显示出偏转，GT将在小行星表面上方沿所需加速度矢量的方向“盘旋”一段时间，以达到所需的速度变化。在整个偏转过程中，对小行星的轨道进行持续监测，并实时了解最终状态。GT的性能包线包括在撞击前受到近距离引力作用的大多数近地天体和在直接撞击地球轨道上直径在150-200米以下的近地天体。
英文摘要：
The Gravity Tractor (GT) is a fully controlled asteroid deflection concept using the mutual gravity between a robotic spacecraft and an asteroid to slowly accelerate the asteroid in the direction of the "hovering" spacecraft. Based on early warning, provided by ground tracking and orbit prediction, it would be deployed a decade or more prior to a potential impact. Ion engines would be utilized for both the rendezvous with the asteroid and the towing phase. Since the GT does not dock with or otherwise physically contact the asteroid during the deflection process there is no requirement for knowledge of the asteroid's shape, composition, rotation state or other "conventional" characteristics. The GT would first reduce the uncertainty in the orbit of the asteroid via Earth tracking of its radio transponder while station keeping with the asteroid. If, after analysis of the more precise asteroid orbit a deflection is indeed indicated, the GT would "hover" above the surface of the asteroid in the direction of the required acceleration vector for a duration adequate to achieve the desired velocity change. The orbit of the asteroid is continuously monitored throughout the deflection process and the end state is known in real time. The performance envelope for the GT includes most NEOs which experience close gravitational encounters prior to impact and those below 150-200 meters in diameter on a direct Earth impact trajectory.
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。
