基于星载加速度计反演载人航天轨道大气密度

热层大气密度直接影响低轨道航天器的精密定轨，热层大气密度模型的误差是影响载人航天定轨精度的关键因素。选取400km为载人航天轨道的代表高度，利用CHAMP卫星数据修正热层大气密度模型，进而反演得到2002年的热层大气密度，统计其中长期变化特征，并分析大气密度与太阳活动和地磁活动的关系，得出热层大气密度与两种指数的总体变化趋势一致的结论，且地磁活动与大气密度的相关性更好。同时将大气密度的反演值与神舟三号飞船的实测密度值进行对比，结果显示二者有较好的一致性，其平均残差和均方根误差分别为0．03和0．24，并且地磁平静期的误差明显小于磁暴期。结果表明，利用星载加速度计数据反演载人航天轨道大气密度是一种有效的方法。

Thermospheric Density of Manned Space Orbit Retrieved from CHAMP Accelerometer Observation

The thermospheric density directly affects the orbit determination precision of low earth orbit spacecrafts, therefore, the error of thermosphere total mass density model is the key for orbit determination and prediction of manned space flight. 400 km was selected as the typical height of the manned space orbit. CHAMP satellite data was used to modify the thermosphere model so as to retrieve the thermospheric total mass density of 2002 from the CHAMP accelerometer observation. Then its middle and long-term variation and its relationship with solar and geomagnetic activities were analyzed which lead to the conclusion that thermospheric density varied consistently with these two activities in general and geomagnetic activities were even closely related to it. The comparison between the density retrieved and the data measured by Shenzhou3 spaceship showed that they were in good consistency with the average error of 0.03 and the root mean square error of 0.24 respective- ly. The error was significantly smaller in geomagnetic calm periods than that in storm phases. The results showed that it was an effective method to retrieve the thermospheric density of the manned spaceship by accelerometer observation of satellites.