USB与VLBI联合确定“嫦娥一号”卫星撞月点的位置

Determination of Impact Site of CE-1 Using USB and VLBI Data

2009年3月1日,"嫦娥一号"卫星成功撞击月球,准确撞击位于月球"丰富海"的预定区域。国内USB和VLBI测控网对撞月过程进行了跟踪测量。撞月飞行段可描述为相对于月心参考系的椭圆轨道,其偏心率约为0.3。本文利用统计定轨方法,联合USB和VLBI数据确定"嫦娥一号"卫星撞月点的位置。通过对撞月前100km×15km环月轨道的测轨数据进行分析,确定了测距系统误差及光压系数参数,并应用于撞月段的短弧轨道计算。将地面接收到卫星信号的最后时刻判定为撞击时刻,根据撞月轨道计算了该时刻"嫦娥一号"在月固系中的位置。为判断该位置是否在月面,结合月面数值高程模型ULCN2005,由该点的月面经纬度确定了该点的月面高程。通过比较由轨道计算得到的落点高程与ULCN2005提供的高程差异,评估了撞月点计算的精度。

Chang＇e-1 deliberately crashed into the moon＇s surface,on the March 3,2009 at 08：13 UTC,thus ending its mission. Using USB and VLBI tracking data,the location of the impact crater is determined by statistical orbit determination. The tracking data before last control is processed to investigate data quality,and the ranging system error and solar radiation pressure coefficient are also determined for the use of the last arc. Our results show that the impact occurred at 52.255oE/1.657oS,and its lunar elevation is 40 meters different from ULCN 2005.