In this project we will evolve the design of the Sinclair Interplanetary (SI) ST-16 small satellite star tracker (SSST). With this redesign we wish to improve the sensor accuracy by an order of magnitude, while maintaining a slew tolerance of up to 1 deg/sec, with >99% availability.. For clarity, in this proposal we will refer to the improved star tracker design as the ST-20. The new design will feature improvements to the sensors optics, sensor processing algorithms, and calibration and focusing procedures.