Sovremennye problemy distantsionnogo zondirovaniya Zemli iz kosmosa, 2026, V. 23, No. 5, pp. 112-120
Correction algorithm of defective pixels in a priori operation mode of star trackers
1 Space Research Institute RAS, Moscow, Russia
Accepted: 07.08.2026
DOI: 10.21046/2070-7401-2026-23-5-112-120
Long-term operation of stellar orientation devices inevitably leads to degradation of their electronic components. Prolonged exposure to radiation on the device’s photodetector leads to an increase in the structural noise of a large number of pixels, transforming them into defects comparable in brightness to pixels containing the useful signal from the stars. When operating in a priori mode, the stellar device knows the angular velocity parameters and the time of the next measurement, which allows predicting limited image areas containing stars and focusing on their processing. This prediction eliminates the negative impact of defects, which occurs when they compete with real stars during execution of the recognition algorithm without prior information, potentially obscuring real stars among a large number of false objects. A negative effect relevant to the a priori mode occurs when the useful signal from a star hits the aforementioned defects resulting in a distortion of the weighted average brightness center of the star, which in turn negatively impacts the performance of the device. Over the course of many years of operation of a star tracker, the magnitude of parameter determination errors can increase by an order of magnitude. Furthermore, the probability of orientation determination will inevitably decrease, potentially reaching zero at high angular velocities. To address these issues, an algorithm for correcting defective pixels for the a priori operating mode is developed and discussed in this paper.
Keywords: star tracker, improved orientation parameter accuracy, elimination of defective pixels
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