Abstract: Star tracker is a type of optical sensor current used widely in spacecraft attitude control system, which provides the most accurate measurement. We study the direct sun irradiation problem of the APS star tracker on orbit, including its effect on the function and performance of star tracker. The experiment and validation schemes are designed. And a clear conclusion is obtained according to the experiment process and verification results. The analysis and experiment results indicate that the ultraviolet irradiation has no significant effect on optical transmittance, and is in the designed allowance range. The direct sun irradiation has no effect on the function and performance of the APS image sensor and star tracker. The analysis and experiment results can be used as the design basis and reference for star tracker subsequent improvement.  

Key words: APS star tracker, direct sun irradiation, effect analysis, experiment verification