Effects of temperature variations on the performance of a space imaging system baffle

Abstract

All the star trackers must be composed of a baffle system to removes stray lights intensity. The baffle is designed to mount in front of the optical system. The performance of a star tracker is often limited by the stray light level on the detector. According to the space conditions, the baffle may deflect due to the temperature variation during the mission. Sun heat flux imposed to the baffle from one side and heat radiates from baffle to the space in all sides. In our case, the baffle is fixed to the satellite structure by four titanium screw. A finite element model has been used to modeling the baffle and temperature distribution and deflection is obtained in worst cold and hot conditions. Results show that in the worst cold condition, baffle is deflected symmetrically whereas in hot case, deflection is not symmetric and the side exposed to the sun light is elongated. Using ray tracing methods along with Monte Carlo algorithm, the baffle efficiency is obtained and compared for both cases. Results show that baffle deflections are not so extreme to force us to cover it with the MLI.