运动学统计定轨法应用于CE-1落月轨迹确定  

Kinematic Statistical Method Using in the Orbit Determination of CE-1

作　　者：李培佳[1,2] 胡小工[1] 黄勇[1] 曹建峰[1,2,3] 

机构地区：[1]中国科学院上海天文台,上海200030 [2]中国科学院研究生院,北京100049 [3]北京航天飞行控制中心,北京100094

出　　处：《天文学进展》2010年第3期290-300,共11页Progress In Astronomy

基　　金：国家自然科学基金资助项目(10703011);国家高技术研究发展专项(2008AA12A209);上海市科学技术委员会资助项目(06DZ22101);科技部"863"课题(2007AA12Z345)

摘　　要：运动学统计定轨方法不同于常规动力学统计定轨方法和几何法,既不需要建立飞行器的动力学模型,又可以利用整个弧段的测量信息进行统计计算,所以采用运动学统计定轨的方法描述飞行轨迹特别适用于嫦娥二期的动力落月过程。对嫦娥一号(CE-1)落月过程,采用运动学统计定轨方法,联合USB和VLBI数据进行轨道计算并确定CE-1的落月轨迹以及撞月点的位置,将所得结果与动力学统计定轨结果进行比较。计算表明,运动学统计定轨方法精度可以满足工程要求,可以为探月工程二期软着陆阶段的导航提供一种较为可行的定轨方法。A kinematical orbit determination method using polynomial functions to describe the short-arc trajectory of a spacecraft is proposed for CE-2＇s planned descending flight toward the landing site on the moon.For kinematical orbit,spacecraft＇s dynamic modeling is not needed and better noise reduction than point positioning method is expected by making full use of all-arc observational data. The first Chinese lunar exploration spacecraft CE-1 performed a free-fall impact on the moon after its mission was accomplished on March 1,2009.The dynamic modeling for its free-fall flight is relatively easy;therefore the dynamic orbit determination strategy has been successfully applied.In this paper,the feasibility of a kinematical method is investigated by processing CE-1＇s free-fall tracking data.For accuracy evaluation,the kinematical trajectory obtained is compared with CE-1＇s dynamical ephemeris. CE-1 was tracked with the national USB（unified S-band） ranging and Doppler tracking network and the national VLBI（Very Long Baseline Interferometry） network.For the proposed kinematical method,this paper focuses on two issues,one is the selection of the degree of the polynomial functions used to describe the short-arc trajectory,and the other is the contribution of the VLBI data. The results indicate that the using of higher order polynomial functions may fit the tracking data better,but it will generate parameter correlation problem,which could deteriorate the accuracy.Simulation experiments and real data processing show that the optimal description of CE-1＇s free-fall landing trajectory is a set of five-order polynomial functions for each of the position components as well as velocity components in J2000.0.We find that the combination of the VLBI delay,delay rate data and the USB ranging data significantly improves the accuracy of the kinematical method than the use of USB data alone.By providing a new method for the determination of its descending trajectory,the accuracy of 20 m for position and 5 cm/s for ve

关 键 词：探月二期 嫦娥一号 运动学方法 统计定轨 落月轨迹 VLBI USB 

分 类 号：P412.41[天文地球—大气科学及气象学]