2016HO3探测任务星载光学观测量建模及定轨

Optical Observations and Its Application on Orbit Determination for 2016HO3 Exploration

以中国首次小行星探测任务为背景,根据星载相机获取的光学影像构造三种观测量,分别为小行星相对于航天器的高度角和方位角、赤经赤纬以及探测器与行星/小行星之间的夹角,分析了其在探测器定轨中的作用。仿真定轨结果表明,观测时长为100 h,探测器三轴位置误差小于50 km,满足工程上对巡航段的轨道精度要求,但x和y方向的位置和速度分量具有较强自相关性。此外还发现,使用单一观测数据类型比联合观测量的定轨精度低3~4个量级,第三类观测量相对于其他两类观测量在定轨精度方面具有显著作用,这表明在2016HO3探测中,利用太阳系大天体的位置信息有助于约束探测器轨道,提高探测器的定轨精度。

Since an upcoming Chinese asteroid mission will target a near Earth asteroid Kamo`oalewa(2016HO3)and a main-belt comets 311P/PANSTARRS,a full simulation analysis has been made on the spacecraft optical navigation based on three types of optical observations collected by on-board cameras.The observations include the elevation and azimuth angle relative to the camera body coordinate system,the right ascension and declination in the celestial reference system,the angle between asteroid and the planets relative to the spacecraft.The dynamical model of the asteroid exploration mission was firstly built and then the celestial bodies could be observed during the mission for the third model was selected,which helped to determine the observation scheme and the pointing direction of the camera.Based on such setting,the observation was simulated which error is about one arcsecond and then the spacecraft orbit determination was calculated.The results indicated that when the observation time reaches 100 h,the 3D position accuracy of the spacecraft could reach 50 km,thus technically meeting the navigation requirement.However,the position and velocity in x and y direction are strongly autocorrelated,which means that the spacecraft position in xy plane cannot be easily constrained using only these optical observations.Meanwhile,the results also shown that the orbit determination accuracy based on single observation type data is 3~4 orders of magnitude lower than that of joint observations.The third-type observations make a much more significant contribution with respect to another two kinds of observations which indicates that the precise position of the solar system bodies is helpful when constraining the position of a spacecraft for 2016HO3 exploration.