载人航天轨道大气密度模式修正研究简

热层大气密度模式的误差,是影响载人航天定轨精度的关键因素.分析载人航天工程所用Jacchia、MSISE、DTM三类大气密度模式的误差特点,通过比较精度和稳定性,基于现有空间天气参数,选取MSISE模式作为基础模式.研究利用星载加速度计数据反演载人航天轨道大气密度的方法,以验证我国载人航天轨道实测数据的精度;同时利用天宫一号以及神舟二号、三号、四号实测密度数据,以及相应的航天测控数据,分析模式误差与地方时、纬度和高度因素之间的关系,讨论建立合适的三维误差库来存储模式误差的方法,研究平均误差修正法和加权误差修正法,建立NRLMSISE-00的误差修正模式.修正结果应用于交会对接任务,与完全不修正时模式平均11.44％的误差相比较,两种修正方法的误差均明显减小,分别为5.41％和4.99％;其中平均误差修正法和加权误差修正法在未来1天、2天、3天的修正结果的误差分别是4.06％、3.73％,6.06％、5.78％,6.13％、5.72％,表明提前1天的修正效果最好;同时比较累积1-5天的误差库滑动也可以看出,误差库累积1天的效果相对较好;比较两种方法的预测效果显示,加权误差修正法优于平均误差修正法.研究表明基于三维误差库的模式修正方法显著提高了载人航天轨道大气密度预测精度,可为交会对接等载人航天任务提供技术支持.

Research on Modification of Atmospheric Density Model in Manned Space Orbit

The error of atmospheric density model is a key factor for orbit determination and predic- tion in manned space flight. By analyzing the error characteristics of three models used in Chinese manned space flight missions including Jacchia, MSISE and DTM and by comparing their precision and stability, MSISE was selected as the basic model for modification. The method to retrieve the at- mospheric density from the satellites accelerator observation was studied to verify the accuracy of Chinese manned spaceerafts density observations. At the same time, the observations of Tiangong 1, Shenzhou 2, Shenzhou 3 and Shenzhou 4 as well as related spaceflight TT＆C data were used to es- tablish a three-dimensional error database by studying the correlativity among models＇ error with local time, latitude and altitude. Finally the modified methods of average error and weighed error were investigated to get the NRLMSISE-00 error-modified model which was used in Chinese rendezvous and docking missions and obviously improved the atmospheric density forecast precision by cutting the models＇ error from the average 11.44% to 5.41% and 4.99% for average error modified method and weighed error modified method respectively. The errors of the modification result for the average error modified methods were 4.06% and 3.73%, 6.06% and for the weighed error modified meth- od were 5.78% , 6.13% and 5.72% respectively for 1 day, 2 days and 3 days forecast. The results showed that the correct effect was the best in 1 day forecast and the error was the smallest when the error database slide cumulated 1 day among the slide cumulating periods of 1 -5 days. The predict results of the two methods showed that the weighed error modified method was better than the average error modified method The study indicates that the model modifying methods based on three-dimensional error database can distinctly improve the precision of atmospheric density prediction and so provide technical support for Chinese manned space flight missions.