Space-Qualified Optical Sensors for ADCS in Small Satellites
The Role of Optical Systems in Enhancing ADCS Performance for Small Satellite Platforms
Attitude Determination and Control Systems (ADCS) are essential for maintaining the precise orientation of small satellite platforms, including CubeSats and microsatellites. High-fidelity optical subsystems—such as star trackers, solar aspect sensors, and Earth horizon sensors—serve as the backbone of inertial reference and vector-based navigation solutions in modern ADCS architectures.
Optical Sensors in Satellite ADCS Architectures
Optical sensing units in spaceflight ADCS provide critical input data for onboard estimators and control algorithms. The most commonly deployed optical sensors include:
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Star trackers: These systems utilize CMOS or CCD focal planes coupled with precision optical assemblies to capture stellar fields, which are then cross-referenced with onboard star catalogs. Sub-arcminute—or even sub-arcsecond—attitude knowledge can be achieved, depending on the system’s optical resolution, thermal stability, and onboard processing capability.
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Sun sensors: Employed for coarse attitude acquisition and Sun vector estimation, these units often use quadrant photodiodes or linear arrays positioned behind pinholes or refractive optics. Angular accuracy is governed by the optical geometry and detector response.
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Earth horizon sensors: Often operating in the thermal infrared (TIR) band, these sensors detect the radiometric contrast between Earth’s limb and space to derive nadir-pointing information and horizon crossing angles. Wide-angle optical elements and bandpass filters are commonly employed to enhance spatial resolution and signal-to-noise ratio.
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