startracker

A startracker, also known as a star tracker or star camera, is a navigation device used to determine the attitude of a spacecraft. It works by imaging the stars and comparing the observed star patterns to an onboard star catalog. By identifying a sufficient number of stars and their positions in the field of view, the startracker can calculate the spacecraft's orientation relative to the celestial sphere with high precision.

The core components of a startracker typically include a lens, an image sensor (like a CCD or CMOS sensor), and a processor. The lens focuses starlight onto the sensor, which captures an image. The processor then analyzes this image, identifying star centroids and comparing them to a stored database of star positions and magnitudes. Algorithms are used to match the observed pattern to the catalog, accounting for potential distortions and noise.

Startrackers are crucial for many space missions as they provide a reliable and autonomous method for attitude determination. Unlike other attitude determination sensors such as sun sensors or gyroscopes, startrackers are not susceptible to the Sun's glare or the drift inherent in gyroscopes, offering superior accuracy for long-duration missions. They are widely used in satellites, space probes, and crewed spacecraft for tasks ranging from precise pointing for scientific instruments to maintaining orbital stability. The accuracy of a startracker depends on factors like the quality of its optics, the resolution of its sensor, the completeness of its star catalog, and the sophistication of its pattern recognition algorithms.