Thermal Design Method and Experimental Verification of Star Sensor System

At present, the research and design of temperature control forstar sensors in domestic institutions are less, and they focus on the image processing and image algorithm optimization of star map. The thermal effect of temperature on the star sensor is analyzed in this manuscript by taking the target energy change, signal-to-noise ratio and centroid positioning error as indexes, so as to realize the reliable application of high-precision star sensor in complex space thermal environment. Furthermore, based on the structure and thermal distribution of star sensor, the thermal design and heat dissipation path optimization of star sensor are carried out,and the thermal control measures of TEC are proposed. The temperature distribution of star sensor is discussed in typical high temperature and low temperature conditions. The validity and rationality of the thermal design are simulated and analyzed by finite element simulation software. On the basis of the above analysis and design, a set of temperature control system is completed. By simulating the environmental conditions of the star sensor under high temperature conditions, the thermoelectric refrigeration method is used to cool the star sensor, so that the temperature of the star sensor detector maintains at 20 ℃±3 ℃. The relationship between thermal environment factors and image quality is clarified, and the correlation analysis between temperature and star recognition accuracy is completed, which provides a direction for future improvement of star sensor attitude determination accuracy.

This article proposes a thermal design optimization scheme for star sensors and designs a temperature control system to implement cooling measures for star sensors operating at high temperatures, in response to the problem of reduced centroid positioning accuracy and imaging quality when they are affected by thermal factors. Based on data analysis, it can be concluded that background noise increases exponentially with the increase of temperature, and the signal-to-noise ratio sharply decreases above 20 ℃; By comparing shot noise and dark current noise, the impact of readout noise on star centroid positioning error was further analyzed from image data. It was found that the background noise of the star map can be kept low at a temperature of 20 ℃, and when the star sensor is kept at or below 20 ℃, the star centroid positioning error is small enough to provide high-precision attitude information for the spacecraft and temperature control indicators for the star sensor. After the design of the temperature control system and the analysis of the temperature control performance test results, the temperature control system has demonstrated excellent control ability and fast voltage response ability, which can maintain the temperature of the star sensor CMOS detector at 20 ℃± 3 ℃. This verifies the rationality and effectiveness of the thermal design scheme proposed in this article, and provides a reference for the future thermal design of star sensors. However, due to limitations in personal ability and experimental conditions, This article has completed the partial principle verification of the star sensor thermal control design scheme on the ground. There are still shortcomings in temperature control accuracy and in orbit test verification of the star sensor thermal design. Further improvement and research will be conducted on this design in the future.