A sun sensor determines a spacecraft’s orientation with respect to the sun. The front surface of the NewSpace Systems (NSS) NFSS-411 sensor is a synthetic sapphire window with a reactive metal coating beneath. Slits are etched in the metal and sunlight passes through them and through an optical filter onto a sensor. The charge on the photo-sensors are read by the microcontroller which processes the image and computes the sun vector.
The vector and other telemetry is returned to the spacecraft through the serial interface. The NCSS-SA05 is based around a PSD analogue sensor. Each sensor comes with a specific calibration equation for maximum accuracy. The unit can be powered from unregulated DC power from the spacecraft.