轨控发动机羽流红外辐射的数值仿真

针对工作在高真空环境下的轨控发动机,数值模拟了其羽流红外特性。首先计算了考虑化学反应的轨控发动机喷管的内流场和外流场,得到了温度、压力、组分浓度等参数的分布。基于HITRAN 2008和HITEMP 2010数据库采用逐线积分法编程计算了气体光谱吸收系数。最后在此基础上用有限体积法建立的求解辐射传输方程的模型,计算得到羽流红外辐射强度在2~10μm范围内随波长变化的曲线。分析了羽流气体组分、波长、探测角度对羽流光谱辐射的影响,与同类文献中的计算结果进行了比较,结果表明：本文的计算模型和方法能较好地模拟轨控发动机羽流的红外辐射特性。     

Solar Activity and the Climate of Prebaikalia

This paper presents convincing evidence for the reality of manifestations of solar variability in climate characteristics of the Prebaikalia. A numerical estimate is obtained of this influence on ground air temperature. It is shown that the main meaningful variations in air temperature in the region for the period1881-1960 were caused by solar activity. Since the 1960s till the present, with the influence of solar variability continuing, a clear-cut influence of another factor has been observed, the role of which has been steadily increasing, and in the hst decade it has now exceeded the contribution of solar variability. Research results on the variations in hydrological characteristics of Lake Baikal and the Angara river and their connection with solar activity are presented. It is shown that these characteristics are closely correlated with the duration of solar cycles.     

跟踪空间非合作目标的一种相对轨道确定方法研究

研究近地轨道卫星沿航向跟踪空间非合作目标的相对轨道确定问题。首先给出以追踪星与非合作目标轨道根数差分描述的相对运动方程;其次根据星间测量几何关系对应的测量方程,提出一种新的基于两步估计的相对轨道确定方法;最后通过数学仿真验证了收敛速度快于扩展卡尔曼滤波,并对初始状态的选取不敏感,具有一定鲁棒性。     

关于HEO空间飞行体的轨道寿命问题

低轨地球卫星的轨道寿命主要取决于大气的耗散作用,其轨道在不断变小(即高度降低)变圆的状态下进入地球稠密大气层中陨落.但HEO(Highly Eccentric Orbit)类型的空间飞行体的运行轨道是一个近地点高度很低,远地点高度却很高的大偏心率椭圆轨道,其轨道寿命主要由第三体(日、月)引力摄动所决定,而且还与其轨道的初始状态有密切关系,特别是慢变量Ω(轨道升交点经度)和ω(轨道近地点幅角),决定了偏心率e的长周期变化状态,从而制约了HEO类型空间飞行体的轨道寿命.本文将根据地球卫星轨道变化规律进行理论分析,阐明这一力学机制,并给出相应的数值验证.     

Improved kHz-SLR tracking techniques and orbit quality analysis for LEO missions

Satellite gravity field missions such as CHAMP, GRACE and GOCE are designed as low Earth orbiting spacecraft (LEO) with orbit heights of about 250–500 km. The challenging mission objectives require a very precise knowledge of the satellite orbit position in space. For these missions precise orbit information is typically provided by GPS satellite-to-satellite tracking (SST) observations supported by satellite laser ranging (SLR).     

静止卫星轨道的高精度确定

基于单站或三站跟踪测轨数据,对静止卫星轨道进行精确确定,提出一种新的有效的轨道确定的算法,星下点位置精度优于30m。     

The ionosphere and the Latin America VLF Network Mexico (LAVNet-Mex) station

In order to detect and study the ionospheric response to solar flares (transient high energy solar radiation), we have constructed a radio receiver station at Mexico City, which is part of the “Latin American Very low frequency Network” (LAVNet-Mex). This station extends to the northern hemisphere the so called “South American VLF Network”.     

Achievable debris orbit prediction accuracy using laser ranging data from a single station

Earlier studies have shown that an orbit prediction accuracy of 20 arc sec ground station pointing error for 1–2 day predictions was achievable for low Earth orbit (LEO) debris using two passes of debris laser ranging (DLR) data from a single station, separated by about 24 h. The accuracy was determined by comparing the predicted orbits with subsequent tracking data from the same station. This accuracy statement might be over-optimistic for other parts of orbit far away from the station. This paper presents the achievable orbit prediction accuracy using satellite laser ranging (SLR) data of Starlette and Larets under a similar data scenario as that of DLR. The SLR data is corrupted with random errors of 1 m standard deviation so that its accuracy is similar to that of DLR data. The accurate ILRS Consolidated Prediction Format orbits are used as reference to compute the orbit prediction errors. The study demonstrates that accuracy of 20 arc sec for 1–2 day predictions is achievable.     

Impact of covariance information of kinematic positions on orbit reconstruction and gravity field recovery

Gravity missions are equipped with onboard Global Positioning System (GPS) receivers for precise orbit determination (POD) and for the extraction of the long wavelength part of the Earth’s gravity field. As positions of low Earth orbiters (LEOs) may be determined from GPS measurements at each observation epoch by geometric means only, it is attractive to derive such kinematic positions in a first step and to use them in a second step as pseudo-observations for gravity field determination. The drawback of not directly using the original GPS measurements is, however, that kinematic positions are correlated due to the ambiguities in the GPS carrier phase observations, which in principle requires covariance information be taken into account. We use GRACE data to show that dynamic or reduced-dynamic orbit parameters are not optimally reconstructed from kinematic positions when only taking epoch-wise covariance information into account, but that essentially the same orbit quality can be achieved as when directly using the GPS measurements, if correlations in time are taken into account over sufficiently long intervals. For orbit reconstruction covariances have to be considered up to one revolution period to avoid ambiguity-induced variations of kinematic positions being erroneously interpreted as orbital variations. For gravity field recovery the advantage is, however, not very pronounced.     

主矢量法在空间近距离拦截优化中的应用

重点研究了在固定时间内利用主矢量原理判断近距离冲量拦截轨道燃料消耗是否最优的问题, 并对非最优情况提出了优化策略. 根据轨道动力学理论, 建立了近距离空间拦截轨道的数学模型. 根据主矢量理论给出了判断冲量拦截是否最优的理论依据, 并给出了优化方法. 利用仿真算例证实了优化的有效性. 通过对不同时间的空间拦截燃料消耗进行仿真比较分析, 提出了燃料消耗最优的拦截策略.