Development of a low cost star tracker for the SHEFEX mission

German Aerospace Center (DLR) is designing and developing a novel star tracker to be used as the primary attitude sensor for the SHEFEX mission. The developed star tracker is considered to be a low cost and low accuracy sensor that is suitable for the proposed mission and the attitude accuracy requirements. This sensor is based on an off-the-shelf camera and a PC/104 computer communicating with the navigation computer. The attitude determination software consists of a processing chain including the camera control, the image processing, the star identification and the attitude estimation.The emphasis of the work is on developing a simple but robust system. Therefore, different algorithm concepts for each element of the chain have been implemented, tested and compared. Several night sky tests and star image simulation software have been implemented and used to verify the performance of the sensor in real-time End-to-End tests. The paper presents the star tracker system, details some newly developed algorithms and analyzes the test results.