中长期轨道预报中大气阻力系数补偿算法的研究

Atmospheric Drag Coefficient Calibration in Medium-Term Orbit Prediction

利用地磁平静期的CHAMP卫星精密星历对多个弧段的大气阻力系数进行解算,找到了适用于轨道预报的最优系数,分析了最优阻力系数与地磁指数、迹向残差的关系,利用线性回归分析建立了大气阻力系数补偿算法。针对中长期轨道预报的需求,该算法能够降低定轨弧段较短条件下阻力系数的解算误差。将该补偿算法应用于不同时期CHAMP卫星和天宫一号的轨道预报,验证了该算法的正确性和普遍适用性,结果表明预报精度能够提高20%以上。

Atmospheric drag coefficient plays an important role in low Earth satellites orbit determination and prediction.Using precise ephemeris of CHAMP satellite in different period,several drag coefficient values are obtained during the orbit determination process,and these values are applied to the orbit prediction.Specially,all the experiments were done in quiet geomagnetic conditions.By comparing prediction position to precise ephemeris,optimal drag coefficient for orbit forecasting is selected.The relations among optimal drag coefficient,geomagnetic indices and trace orientation error are studied.Subsequently,according to linear regression analysis a drag coefficient correction method is proposed.For the purpose of medium-term orbit prediction with short-term observation,drag coefficient error is reduced by using this method.In addition,the method is applied to verify its validity in CHAMP and Tiangong-1 orbit determination and prediction for different periods.The results show that orbit prediction accuracy is improved by more than 20%.