What are Star Trackers?

Star Trackers are high-precision optical attitude determination sensors that compute spacecraft orientation by imaging star fields and matching observed star patterns against an onboard catalog. The sensor typically consists of a radiation-tolerant imaging detector, optical assembly, baffle system, and embedded processing electronics. By determining the centroids of detected stars and performing pattern recognition, the star tracker calculates the spacecraft’s absolute attitude in an inertial reference frame with high accuracy and low drift.

Within the attitude determination and control subsystem, star trackers provide continuous quaternion or Euler angle outputs to support fine-pointing missions such as Earth observation, astronomical observation, inter-satellite communication, and precision antenna alignment. Performance depends on optical quality, detector sensitivity, onboard processing capability, and robustness to stray light and dynamic motion. Proper integration ensures stable alignment with the spacecraft reference frame and reliable operation under the mission’s thermal, radiation, and dynamic conditions.

Key specifications of Star Tracker - 

• Satellite Type: This parameter defines the spacecraft class and mission environment in which the star tracker will operate. Satellite type influences structural mounting strategy, redundancy philosophy, environmental qualification, and pointing stability requirements. Operational orbit, disturbance levels, and mission-critical pointing objectives determine the required sensor robustness and performance characteristics.
• Altitude Accuracy: Altitude accuracy refers to the precision of the attitude determination solution delivered by the star tracker. It defines the angular error between the measured spacecraft orientation and the true inertial reference. Higher attitude accuracy directly enhances pointing performance, payload alignment, and control loop stability, particularly for missions requiring fine angular resolution and minimal drift.
• Mass: The mass of the star tracker impacts spacecraft mass allocation, structural support design, and overall inertia distribution. It must be considered in relation to mounting location, vibration loads during launch, and alignment stability throughout the mission. Mass optimization is critical for platforms with strict payload and bus mass constraints.
• Slew Rate: Slew rate defines the maximum angular velocity at which the star tracker can reliably maintain attitude determination. It determines the sensor’s ability to operate during rapid spacecraft maneuvers without losing star pattern lock. Adequate slew rate capability ensures continuous attitude updates during dynamic operations and reduces reacquisition time after large-angle maneuvers.
• Data Update Rate: Data update rate specifies the frequency at which attitude solutions are provided to the spacecraft avionics. It affects control loop bandwidth, responsiveness, and jitter suppression capability. Higher update rates support tighter control loops and improved disturbance rejection in precision pointing missions.
• Supply Voltage: Supply voltage defines the electrical input required for the imaging sensor, processing electronics, and thermal control elements. It must be compatible with the spacecraft power distribution system. Stable voltage regulation is essential to maintain detector performance, processing reliability, and consistent attitude solution quality.
• Interface: The interface parameter includes mechanical mounting provisions, electrical power connections, command and telemetry communication, and thermal interfaces. Mechanical alignment accuracy directly affects attitude solution fidelity, while data interfaces must integrate seamlessly with onboard computers and attitude control algorithms. Proper interface definition ensures reliable performance within the spacecraft’s overall system architecture.

The Largest Database of Star Tracker

SatNow has listed Star Tracker from the leading manufacturers and made them searchable by specification. You can enter the key parameters and the search tool will scan catalogs from the leading manufacturers to identify products that meet your spec. Once you find Star Tracker that meet your requirement, you can view product information, download datasheets or request quotations. Quotation requests will be routed to the manufacturer of the product who will get back to you directly. The quotation will also be routed to distributors of the product in your region.