What is the purpose of a star tracker in a satellite ADC?

Satellite ADC systems enable satellites to determine current attitude and adjust it as needed.

They rely on sensors, actuators, and algorithms working together.

Common sensors include:

– Gyroscopes

– Sun Sensors

– Earth Horizon Sensors

– Magnetometers

What is a Star Tracker? 

Star trackers capture star field images.

They compare images with preloaded star catalogs.

Thus, they compute satellite attitude.

Unlike sensors using Earth’s magnetic field or Sun position, star trackers use fixed stars as a cosmic reference frame.

Core Role of Star Trackers in Satellite ADC 

– Relative vs. Absolute Measurement: Gyroscopes track attitude changes only.

Star trackers provide absolute reference to the celestial sphere.

– System Initialization and Recovery: After launch or tumbling anomalies, star trackers enable cold-start attitude determination from scratch.

Star Tracker Advantages 

1. Ultra-High Precision: Star trackers achieve better than 1 arcsecond accuracy.

They far surpass sun sensors (~0.1°) and magnetometers (1–2°).

2. Strong Robustness: They resist magnetic interference and atmospheric effects.

Therefore, they suit all orbit types.

3. High Autonomy: Star trackers need no prior attitude knowledge.

They operate independently.

4. Multi-Mission Adaptability: They fit LEO, GEO, and interstellar missions.

Miniaturized designs reduce costs.

5. Redundant Design: Engineers often pair them for fault tolerance.

Star trackers provide high-precision, autonomous absolute attitude determination in satellite ADC.

Consequently, spacecraft stabilize, point precisely, and survive long-term in extreme space environments.