A star tracker is an optical navigation sensor that determines spacecraft attitude by observing stars. The device captures star field images and then compares them with an onboard star catalog. As a result, it calculates the spacecraft’s attitude information.
In spacecraft systems, thermal stability directly affects attitude determination accuracy. Moreover, the space environment introduces extreme thermal conditions. A spacecraft may simultaneously experience solar radiation, deep-space cold temperatures, planetary infrared radiation, and heat generated by onboard electronic equipment.
Optical Distortion
The optical lens system expands or contracts as temperature changes. Even small deformations may shift the focal plane. Consequently, the accuracy of star centroid positioning decreases and pointing errors increase.
Increased Sensor Noise
Most star trackers use CMOS or CCD image sensors. High temperatures increase dark current and image noise. Therefore, star identification capability declines, especially when the system observes dim stars.
Mechanical Misalignment
Different materials have different coefficients of thermal expansion. As a result, thermal expansion may change the relative positions among the optical system, detector array, and structural components.
Reduced Electronic Performance
Electronic circuits usually need to operate within a specific temperature range. Excessive temperatures may affect the performance of processors, memory chips, and power systems.
Shortened Service Life
Continuous thermal cycling accelerates material fatigue. Over time, repeated heating and cooling may damage optical coatings, solder joints, and structural connection points.
Main Objectives of Star Tracker Thermal Control
An efficient thermal control system usually needs to achieve the following goals.
Maintain Stable Operating Temperature
The system must ensure that critical components always remain within the allowable temperature range.
Reduce Thermal Gradients
Non-uniform temperatures may cause structural deformation. Therefore, engineers need to minimize temperature differences among various parts of the optical components.
Improve Measurement Accuracy
Stable temperatures help maintain constant focal length, detector sensitivity, and optical alignment.
Improve Reliability
Thermal management can prevent equipment overheating and thermal fatigue.
Extend Mission Life
Long-term thermal stability can support multi-year on-orbit missions.
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TY-Space Technology (Beijing) Ltd. is professional focusing on advanced attitude optical sensors, especially Star Trackers for space industry.