The relationship between star tracker and satellite measurement and control

Star tracker and satellite measurement and control are two closely related technical fields in satellite missions. Star tracker are a key component of the Satellite Attitude Control System (ACS), and the Satellite Tracking and Command (TTC) system is the infrastructure that ensures the normal operation and mission execution of satellites in orbit. The relationship between the two can be analyzed from the following aspects:

The functions of star tracker

A Star Tracker is a device used to measure satellite attitude, which determines the satellite’s attitude (i.e. the direction of the satellite relative to the reference frame) by capturing star images and matching them with known star maps. The main functions include:

High precision attitude measurement: providing accurate attitude information to enable satellites to correctly point towards the target.

Real time attitude update: Continuously updating attitude information during flight to ensure real-time control of satellite attitude.

The functions of satellite measurement and control

The satellite measurement and control system mainly includes the following parts:

Telemetry: Real time monitoring of satellite status to obtain operational data of various satellite subsystems.

Tracking: Determine and predict the orbital position of a satellite to ensure its operation on a predetermined orbit.

Command: Send operational instructions to the satellite, including attitude adjustment, orbit correction, and task execution.

The role of star tracker in satellite measurement and control

The role of star tracker in satellite measurement and control is reflected in the following aspects:

Attitude control:

The high-precision attitude information provided by star tracker is the foundation of attitude control systems, ensuring that satellites can stably point towards targets, such as Earth observation satellites pointing towards the Earth’s surface, communication satellites pointing towards ground receiving stations, scientific satellites pointing towards deep space celestial bodies, etc.

The attitude control system adjusts the satellite’s attitude through actuators such as reaction wheels, magnetic torque converters, or thrusters based on the data provided by the star tracker .

Orbit and attitude determination:

During the measurement and control process, the ground station needs to obtain satellite orbit and attitude information to ensure that the satellite operates on the predetermined orbit and can perform tasks correctly.

The attitude data provided by the star tracker is combined with the tracking data of the ground station to help the measurement and control system accurately determine the spatial position and attitude of the satellite.

Fault detection and recovery:

If the satellite attitude is abnormal, the star tracker can help detect attitude deviation and provide necessary data for attitude recovery operations.

When an abnormal satellite attitude is detected at the ground station, commands are sent to the satellite through the measurement and control system, and the attitude is adjusted to a normal state based on feedback data from the star tracker .

Data synchronization and timestamp:

High precision attitude information is crucial for the temporal synchronization and spatial labeling of scientific data. For example, Earth observation satellites require accurate attitude information for geographic location calibration when capturing images.

The data from the star tracker ensures that the satellite maintains a highly consistent temporal and spatial information during observation and measurement tasks.

Collaboration between star tracker and other measurement and control equipment

Star tracker work together with other measurement and control equipment (such as gyroscopes, accelerometers, GPS receivers, etc.) to complete satellite measurement and control tasks:

Redundancy and complementarity: Star tracker work together with other attitude measurement devices to provide redundant and complementary information, ensuring the reliability and accuracy of attitude measurement.

Data fusion: By fusing data from star tracker and other measurement devices, the attitude control system can obtain more accurate attitude information and improve attitude control accuracy.

To sum up，Star tracker play a crucial role in satellite measurement and control systems. The high-precision attitude information it provides is the foundation for the smooth progress of attitude control and measurement and control tasks. Through collaborative work with other measurement and control devices, star tracker ensure that satellites can operate stably and accurately in predetermined orbits and attitudes, effectively performing various tasks such as science, communication, navigation, etc. The satellite measurement and control system relies on the data from star tracker for real-time monitoring, command sending, and abnormal recovery, ensuring the overall operational safety and mission success of the satellite.