北斗GEO卫星南北控制对半长轴影响分析

在北斗GEO（Geostationary Earth Orbit，地球静止轨道）卫星南北控制期间，陀螺漂移、姿态控制、轨道平面变化等因素都会对卫星轨道半长轴产生影响，进而影响卫星星下点经度漂移，而在实际工程中难以提前准确预估南北控制对半长轴的影响。根据GEO卫星南北控制特点，分析了各因素对半长轴影响的原因，通过影响因素剥离的方法建立了各因素对半长轴影响的模型，利用在轨GEO卫星历次南北控制的实际数据，验证了模型的准确性并给出了各个因素的影响量级。结果表明，该模型可使得南北控制对半长轴影响的预测精度达到1 km以内，可用于北斗GEO卫星南北控制时半长轴补偿控制。

Analysis of the Semi-Major Axis Changed by North-South Control of BeiDou GEO Satellites

During north-south control of BeiDou Geostationary Earth Orbit (GEO) satellites, the semi-major axis was changed due to influence of factors such as gyro drift, attitude control and orbital plane change, and this caused drift of the ground longitude. Consequently, it was hard to accurately estimate the effect of north-south control on the semi-major axis in practice. Based on the north-south control characteristics of the GEO satellites, the reasons of various factors affecting the semi-major axis have been analyzed. The model of various factors influencing the semi-major axis was established by stripping the factors. The accuracy of the model was verified by using the data of previous north-south control of GEO satellites in orbit. The magnitude of each influencing factor is given. The results show that the estimated error of the model is less than 1km. The model can be used to compensate the semi-major axis in north-south control of BeiDou GEO satellites.