Degradation mechanism of star sensor performance caused by radiation damage of CMOS image sensor

In order to analyze the reasons for star sensor performance degradation and the decrease of attitude measurement accuracy, performance degradation mechanisms of star sensor caused by Complementary Metal Oxide Semiconductor (CMOS) image sensor radiation damage were mainly studied. By establishing the correlation among the spatial radiation, radiation sensitive parameters of CMOS image sensor and the performance parameters of star sensor, the transmission mechanism from CMOS image sensor device parameters degradation to star sensor system parameters degradation was revealed. The 60Co-γ irradiation test showed that the decrease of signal-to-noise ratio led to the decrease of star sensor detection sensitivity after irradiation, and the signal-to-noise ratio was the bridge between the CMOS image sensor and the star sensor system. The proton irradiation test showed that when the irradiation fluence was more than 3.68×1010 p/cm^2, the star point centroid could not be extracted correctly. The results lay a certain foundation for the research of star sensor attitude measurement error and correction technology, and also provide some theoretical basis for the design of high-precision star sensor.

The article proposes a quantitative evaluation method for the performance of star sensor systems after irradiation based on signal-to-noise ratio. The innovation of this method lies in establishing the correlation between spatial radiation and CMOS image sensor radiation damage sensitivity parameters, as well as star sensor performance parameters. The dark current noise and dark signal non-uniformity noise of CMOS image sensors are the main factors leading to the degradation of star sensor performance. By establishing a relationship between the noise of CMOS image sensors and the star sensor’s star magnitude detection sensitivity through the system signal-to-noise ratio, a prediction method for the performance parameter degradation of star sensors after irradiation is finally obtained. The experimental results indicate that an increase in the noise of CMOS image sensors (dark current noise and dark signal non-uniformity noise) leads to a decrease in the signal-to-noise ratio of the system. However, a decrease in the signal-to-noise ratio of the system can also lead to a decrease in the sensitivity of the star sensor to detect magnitude. Proton irradiation test found that when the irradiation dose is greater than 3.68 × At 10 ^ 10 p/cm2, it is no longer possible to accurately extract the centroid of the star point. The proton displacement damage of the CMOS image sensor has a more serious impact on the performance degradation of the star sensor, but further analysis of the relevant mechanism is needed. The research conducted has analyzed the impact of space radiation on the performance parameters of star sensors from a system level perspective, laying the foundation for the research on prediction and correction techniques for on-orbit attitude measurement errors of star sensors.