Autonomous attitude determination by starry sky image processing

A method of spacecraft attitude determination by starry sky image processing is presented. It can be considered as a basis of fully autonomous attitude determination system. The system enables to determine the orientation of the spacecraft in near-real time directly onboard. It consists of a digital camera fixed on the body of the spacecraft and an onboard computer with a central processing unit for floating point calculations and an external storage with a star catalog stored. To support the functioning of the system two algorithms have been developed. The first algorithm separates the stars from the background noise and determines their coordinates in the plane of the image. The second algorithm identifies the stars using the star catalog. Based on the results attitude determination is calculated by minimizing the differences between the star coordinates.