This book addresses novel techniques in determining gyroless micro-satellite attitude and attitude rate. The main objective of this proposal is to explore the possibility of using commercially available low cost micro-light star sensor as a stand-alone sensor for micro-satellite attitude as well as attitude rate determination. The objective is achieved by developing accurate and computationally efficient algorithms for the realization of onboard operation of a low fidelity star sensor. All the algorithms developed here are tested with the measurement noise presented in the catalog of the sensor array STAR-1000. Proposed methods achieve desired accuracy while estimating satellite attitude and attitude rate using low fidelity star sensor data. Also, they require lower on-board processing requirement and less memory allocation; thus are suitable for micro-satellite applications.