地气光辐射对空间目标成像特性影响分析

为分析地气光辐射对空间目标成像特性的影响，以地球同步轨道(GEO)卫星搭载的可见光成像器为探测平台，利用卫星工具包(STK)设计高椭圆轨道(HEO)及近地轨道(LEO)目标运动场景，根据空间目标、地球、太阳、探测平台之间的位置关系，采用微元法建立空间目标与地气光背景等效星等模型，推导出空间目标信噪比(SNR)计算公式。分析了距离、角度参数变化对不同轨道空间目标、地气光背景等效星等及空间目标信噪比的影响。仿真结果表明:当探测平台距离空间目标较远时，地气光背景等效星等低于空间目标等效星等，地气光辐射比空间目标信号强。当地气光辐射进入和离开空间目标探测视场时，空间目标信噪比最大，该时间段是进行空间目标探测的最佳“观测窗口”。仿真得出的空间目标信噪比值为空间目标探测识别提供了理论计算依据。 

Influence of earth-atmosphere radiation on imaging characteristics of space object

To analyze the influence of earth-atmosphere radiation on imaging characteristics of space object, first, the visible light imager mounted on Geosynchronous Orbit (GEO) satellite was treated as an observation platform, and the motion scenes of Highly Elliptical Orbit (HEO) and Low Earth Orbit (LEO) objects were designed by the Satellite Tool Kit (STK). Then, the equivalent magnitude model of space object and earth-atmosphere background, and the calculation formulation for the Signal-to-Noise Ratio (SNR) of space object were derived by adopting infinitesimal method, according to the relative relationship among the space object, the sun, the earth and the observation platform. The effects of the distance and angle variables on the equivalent magnitude of different orbital objects and earth-atmosphere, as well as the SNR were analyzed. The simulation results indicate that the equivalent magnitude of earth-atmosphere background is lower than space object while the object is far away from the observation platform, which means that the earth-atmosphere radiation is stronger than the target signal. The observation window between the time when the earth-atmosphere radiation enters and leaves the target detecting field of view is the best time for target detection since the SNR is the largest. Moreover, the value of SNR obtained by simulation provides a theoretical calculation basis for the detection and recognition of space object.