Analysis of Flow Field Aero-Optical Effects on the Imaging by Near-Earth Space All-Time Short-Wave Infrared Star Sensors

Abstract

In order to study the performance of the all-time short-wave infrared (SWIR) star sensor mounted on a high-speed platform in near-earth space, a model of aero-optical effects is established to quantitatively analyze the influence of the flow field on its imaging. Firstly, the LES model is chosen to calculate the external flow field characteristics. Then, the degradation results of the transmission effect are analyzed based on the refractive index field, and the imaging degradation model of the star sensor under aero-thermal conditions is constructed. The optical transmission effect simulation shows that the star point offset increases with the rise of flight speed. Compared with the visible band, when the velocity reaches 8Ma, the star point offset in the J, H, and Ks bands declines by 46.6%, 62.1%, and 71.1%, respectively. The research on the thermal radiation effect presents that the stargazing ability of star sensors is barely affected with a speed of no more than 4Ma. As the speed increases to 8Ma, the detectable limiting magnitudes of the J, H, and Ks bands are 3.943, 2.674, and 1.313. H band and the middle region are suggested to maximize the performance of SWIR star sensors. The research quantitatively analyzes the influence of flow field aero-optical effects on the image quality, which provides theoretical support for the system design, parameter selection, and installation position of SWIR star sensors applied in near-earth space.