Star sensor radiation resistance

Star Sensor, also known as Star Tracker, serves as an essential core optical sensor in spacecraft attitude determination systems. High-energy radiation in space affects its accuracy.

Space Radiation Environment Poses Threats to Star Sensors

Space radiation environment is complex and diverse. It mainly includes three major types: Total Ionizing Dose (TID), Single Event Effects (SEE), and Displacement Damage (DD). These radiations come from the Van Allen radiation belts, galactic cosmic rays, solar proton events, and high-energy protons and electrons trapped by Earth’s magnetic field.

For star sensors, the core component is the image sensor. Radiation particles directly act on these photoelectric devices and affect their functions.

Radiation Impacts Star Sensor Performance

Radiation degrades star image quality. Background noise increases, and star point grayscale distribution changes. Bright hot pixels may overlap with real stars. This causes star saturation or misidentification.

Radiation increases star identification and centroid positioning errors. Traditional star map recognition algorithms (such as triangle algorithm, pyramid algorithm, and grid algorithm) are sensitive to noise. Hot pixels alter the calculation of inter-star cosine values. As a result, identification fails. Centroid positioning error rises from sub-pixel level to a degree that affects attitude output.

Radiation reduces dynamic performance. In high-dynamic environments (such as rapid satellite orbital maneuvers), radiation-induced trailing effects combine with noise. This further worsens attitude update rate and accuracy.

Radiation causes long-term on-orbit degradation. Even if initial performance is good, device parameters (such as dark current) continue to deteriorate as cumulative dose increases. This may eventually prevent the star sensor from working normally.

Key technologies to enhance the radiation resistance of star sensors include device-level radiation-hardened design, reinforcement of electronic components and structures, algorithm and software-level improvements, and system-level design optimization.