Abstract:  In order to analyze the influence of earth atmosphere radiation on imaging characteristics of space object for different detection methods, a moving and detecting scene of space object was designed with STK, where the visible light imagers mounted on the GEO and MEO satellites were set as detecting platform, the HEO satellite was set as object. Models of space object and earth atmosphere radiation were built with infinitesimal method, and then the SNR of space object was derived. Furthermore, both tracking and gazing detectors were disposed on each detecting platform to analyze the change rule of SNR with different detecting models. The simulation results indicate that the target SNR obtained by the middle orbit detector is stronger than the high orbit detector; the target SNR of tracking detector is stronger than that of gazing detector on the same detecting platform; the difference of SNR is maximal as the space object entering or leaving the detecting field of view, yet it is minimal as the object is close to the center of detector's field of view. 

Key words: earth atmosphere radiation, space object, equivalent magnitude, signal-to-noise ratio, satellite simulation tool kit