基于北斗星间链路的IGSO/GEO航天器定轨研究

Orbit Determination of IGSO/GEO Spacecraft Using BeiDou Inter-Satellite Link

  • 摘要: 星间链路(inter-satellite link,ISL)技术可实现导航卫星自主定轨和提高定轨精度,也可以支持用户航天器定轨。以北斗倾斜地球同步轨道( inclined geosynchronous orbit,IGSO)和地球静止轨道(geostationary earth orbit,GEO)卫星模拟用户航天器,使用与北斗中圆地球轨道(medium earth orbit,MEO)卫星建链的实测Ka波段星间链路双向观测数据,研究了基于北斗星间链路的用户航天器定轨方法,开展了定轨实验,并重点分析了参与建链的北斗MEO卫星在不同轨道面分布、卫星数量、建链时间分布和时长下IGSO/GEO卫星定轨精度。结果表明:建链卫星分布的轨道面越多,定轨精度越高,当6颗建链MEO卫星分布于3个轨道面时,IGSO和GEO卫星轨道的三维均方根(three-dimensional root mean square,3D RMS)误差分别达到为45.3 cm和55.0 cm; IGSO和GEO卫星定轨精度随着建链MEO卫星数量增加而逐渐提高,卫星数量增加至9颗时趋于平稳,24颗MEO卫星情况下,C39和C60卫星定轨精度3D RMS提高至15.8cm和19.1 cm;卫星建链时间分布均匀,建链时长越长,定轨精度越高,建链时间均匀分布时建链时长由4h增加至12h,IGSO和GEO卫星定轨精度3D RMS分别为16.5 cm和26.2 cm,提高幅度分别为47.6%和70.6%。

     

    Abstract: Objectives: Inter-satellite link (ISL) technology can realize autonomous orbit determination of navigation satellites and improve accuracy of orbit determination. It can also support orbit determination of user spacecrafts, and the performance of orbit determination for user spacecraft with BeiDou inter-satellite link has not been validated. Methods: BeiDou medium earth orbit (MEO) satellites serve as reference satellites, BeiDou inclined geosynchronous orbit (IGSO) and geostationary earth orbit (GEO) satellites are used as user spacecrafts, and real inter-satellite link data between them are used to study orbit determination method of user spacecraft. Orbit determination experiments of IGSO and GEO satellites under different orbital plane distribution, number of satellites, link time distribution and duration of MEO satellites are carried out, and the orbit accuracy of IGSO and GEO satellites are analyzed in detail. Results: Results show that MEO satellites with established links are distributed across more orbital planes, the orbit determination accuracy of IGSO/GEO satellites is better. When 6 linked MEO satellites are distributed across three orbital planes, three-dimensional root mean square (3D RMS) of IGSO and GEO orbit errors are 45.3 cm and 55.0 cm, respectively. Compared to MEO satellites distributed in one or two orbital planes, orbit determination accuracies of IGSO/MEO are improved by 11.4%, 62.3% and 6.0%, 17.0%. When MEO satellites are evenly distributed across three orbital planes, the orbit accuracy of IGSO/GEO satellites improves as the number of the linked MEO satellites increases. When the number of satellites is increased from 3 to 9, the 3D RMS of IGSO and GEO orbit errors are improved from 79.4 cm and 150.8 cm to 34.6 cm and 38.3 cm, respectively. When the number of MEO satellites is increased to 24, the orbit determination accuracy of IGSO and GEO satellites are improved by 80.1% and 87.3% with 3D RMS reaching 15.8 cm and 19.1 cm, respectively. When using all 24 MEO satellites, the more uniform time distribution of satellite links and the longer linked time, the higher orbit determination accuracy. When 4-hour link duration is evenly distributed, orbit determination accuracy of IGSO and GEO satellites are 31.5 cm and 89.1 cm, respectively. When the linked duration is increased from 4 h to 12 h, the 3D RMS of IGSO and GEO orbit errors reach 16.5 cm and 26.2 cm with an improvement of 47.6% and 70.6%, respectively. The accuracy improvement is not significant when the linked duration is further increased. Conclusions: This study demonstrates that the BDS-3 inter-satellite link can provide orbit determination services for user spacecrafts with decimeter-level accuracy.

     

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