Thermal effect on star sensor

Abstract

The star sensor is a high-precision attitude measurement device widely used in aerospace vehicles. One of the most significant influence on the accuracy of star sensor is the operating temperature. Experiments show that with the increase of temperature, the dark current noise of CMOS increases exponentially, which greatly reduces the Signal-to-Noise ratio(SNR) of the star map. A novel and efficient thermal control design is presented in this manuscript, for the purpose of keeping the temperature of CMOS and temperature fluctuation in a limited range. To validate the design, thermal analysis of the model of CMOS assemblies are built by utilizing finite element method. During orbital operation, the temperature of the optical system of the star sensor is unevenly distributed. The structural parameters such as the refractive index of the lens, the thickness of the lens, and the curvature radius will change, affecting the imaging position and energy distribution of the star point. Star point extraction and positioning accuracy will be greatly affected. These jobs could give some guidance and reference for the precise thermal control of CMOS assembly of other space optical camera.