“嫦娥二号”小行星探测试验定轨计算与分析

嫦娥二号于2012-04-15开展对图塔蒂斯小行星的探测试验，至2012-12-13与图塔蒂斯交会，共飞行243 d，这是我国对小行星的首次探测.因为未安装星载导航设备，CE-2 在小行星探测试验的全过程均基于地基USB（Unified S-Band）与甚长基线干涉测量技术（VLBI，Very Long Baseline Interferometry）测量实现导航.对小行星探测期间的定轨计算及精度分析进行了讨论，对我国新建深空站的测量数据进行了分析.针对交会前最后一次轨道机动后，仅有13 d控后数据的现状，提出了快速轨道重建策略.计算结果表明该策略不仅可以有效改进定轨计算精度，还可以实现轨控速度增量的标定.基于重叠弧段的轨道分析比较表明，单独使用USB长弧数据计算可以获得10 km的定轨精度，综合USB与VLBI数据联合定轨，定轨精度可以提高1倍.

Orbit determination and analysis for Chang’E-2 asteroid exploration

Chang'E-2(CE-2) performed China's first asteroid exploration from April 15th, and took 243 days to fly-by with the asteroid Toutatis on December 13rd, 2012. Because of no navigation camera onboard, the navigation for CE-2 is dependent on the ground-based unified S-band (USB) and very long baseline interferometry (VLBI) tracking system. The orbit determination and orbital accuracy of CE-2 was discussed, and the tracking data from China's new built deep space network was analyzed. With only 13 days left before CE-2's encounter with the asteroid following its previous orbit correction, a new orbit determination strategy was proposed. And a better orbit accuracy can be brought by the combination of data before and after the orbit control. According to the overlap comparison, an orbit solution of 10 km accuracy can be obtained using only USB tracking data, while the joint use of USB and VLBI can improve the accuracy by one time.