使用体积离散方法计算不规则小天体表面重力场

发布时间：2018-11-12 07:23

【摘要】：在小行星探测任务中,航天器轨道设计需要充分考虑到小行星的非球形引力场的影响.太阳系中大部分小行星具有形状不规则、密度不均匀的特点,因此,在没有绕飞轨道数据的情况下,精确计算其引力场非常困难.利用不规则小行星的多面体模型,采用体积离散方法通过直接积分计算小行星引力场球谐系数和表面重力场分布情况.将该方法与多面体方法进行了比较,并以(433)Eros为例,通过该方法计算得到的结果与NEAR(Near-Earth Asteroid Rendezvous)探测器的轨道数据反演结果比较,C20项误差不超过2%,使用该方法对我国小行星探测任务拟探测的(1996)FG3小行星的重力场进行了计算.以嫦娥二号探测器飞越的(4179)Toutatis小行星为例,结合相应的雷达观测数据提供的小行星形状模型,计算其表面引力势情况,为通过飞越任务获取的光学图像分析其表壤的分布、流向等提供了相应的理论依据.该方法适用于密度不均匀天体,可为小行星探测任务轨道设计和着陆提供可靠的小行星引力场数据.
[Abstract]:In asteroid exploration missions, spacecraft orbit design needs to fully take into account the impact of the asteroid's non-spherical gravitational field. Most asteroids in the solar system have the characteristics of irregular shape and uneven density, so it is very difficult to calculate the gravitational field accurately without orbiting data. Based on the polyhedron model of irregular asteroid, the spherical harmonic coefficient of asteroid gravitational field and the distribution of surface gravity field are calculated by volume discretization method through direct integration. The method is compared with the polyhedron method. Taking (433) Eros as an example, the result obtained by this method is compared with that of NEAR (Near-Earth Asteroid Rendezvous) detector). The error of C20 term is less than 2. The gravity field of (1996) FG3 asteroid to be detected by the Chinese asteroid exploration mission is calculated by using this method. Taking the (4179) Toutatis asteroid flying by the Chang 'e-2 probe as an example and combining the shape model of the asteroid provided by the corresponding radar observation data, the surface gravitational potential of the asteroid is calculated, and the distribution of the surface soil is analyzed for the optical images obtained by the overflight mission. The flow direction and so on provide the corresponding theoretical basis. This method is suitable for non-uniform density celestial bodies and can provide reliable data of asteroid gravitational field for asteroid exploration mission orbit design and landing.
【作者单位】：中国科学院紫金山天文台;中国科学院行星科学重点实验室;
【基金】：国家自然科学基金项目(11303103,11473073)资助
【分类号】：P185.7

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