“天问一号”太阳等离子体延迟误差分析与修正

Analysis of Delay Error Correction of Solar Plasma Region on Tianwen-1

当电磁波穿过行星际空间区域飞行时,太阳等离子体给测控通信信号带来较大的反射损耗并降低测控通信信号的功率。分析了等离子体延迟误差与深空探测器测控的影响,讨论了等离子体延迟误差与太阳–地球–探测器夹角SEP、探测器与日心距离r的关系,将仿真结果和“天问一号”在轨实测数据进行对比验证。结果表明,等离子体延迟随着SEP和r的增大而减小,深空航天器精密测定轨时必须考虑太阳等离子体的延迟影响,对等离子体延迟误差修正后,再经动力学轨道改进可消除残余误差。

When electromagnetic wave flies through the interplanetary space region,the solar plasma will bring large reflection loss to the TT&C communication signal and reduce the power of the TT&C communication signal.The influence of time delay error of electromagnetic wave on ranging can reach tens of meters in one way.In this paper,the formation principle of the solar plasma region was analyzed,the relationship between the plasma delay error and the angle of Sun-Earth-Probe(SEP)and the distance r between the detector and the sun center was simulated,and the influence of the solar plasma time delay of Tianwen-1 on ranging was discussed.The results show that the plasma delay decreases with the increase of the SEP and r,and the effect of solar plasma delay on ranging is less than 2 m due to the SEP more than 20°in the Earth-Mars transfer orbit and the initial orbit of the circum-Mars,while the two-way effect of solar plasma time delay on ranging increases gradually from about 2~100 m when the SEP is less than 20°and close to 0°.The delay effect of solar plasma must be considered in precise orbit determination.After plasma delay error correction of ranging data,the residual error can be eliminated by dynamic orbit improvement,and the final residual error of orbit determination can reach within 4 m.