Photometric Measurement Performance Evaluation of Star Sensors Based on Finite Element Computational Model

Photometric measurement performance evaluation of star sensors is a prerequisite for navigation and observation. In this paper, the OpenGL technology is used to establish a computational model of the complex target OCS. Through numerical calculation and finite element analysis, the target is divided into multiple tiny surface elements. The scattering characteristics of each surface element are calculated one by one and then superimposed to form the total scattering characteristics of the target, which can more realistically reflect the photometric characteristics of the target. Then, considering the occlusion of the Earth's shadow and the motion relationship, the curves of the target's photometric changes within the field of view of the star sensor in different seasons are calculated. The difference between the peaks and troughs of the periodic oscillations is about 0.5 magnitudes. Moreover, a navigation star catalog is established according to the projection of the stellar density, and a photometric calibration method for the star sensor is provided. Selecting stars with a brightness within the range of 9 to 11 magnitudes as the navigation star catalog can not only make the navigation stars have a similar brightness to the target, but also meet the requirements of the star sensor's star map recognition, which helps to evaluate the photometric measurement performance of the star sensor more quickly and accurately.