A Survey on Star Identification Algorithms

Abstract: The author surveys algorithms used in star identification, commonly used in startrackers to determine the attitude of a spacecraft. Star trackers are a staple of attitude deter-mination systems for most types of satellites. The paper covers: (a) lost-in-space algorithms (when no a priori attitude information is available), (b) recursive algorithms (when some apriori attitude information is available), and (c) non-dimensional algorithms (when the startracker calibration is not well-known). The performance of selected algorithms and support-ing algorithms are compared.Keywords: Star Identification; Attitude Estimation; Star Tracker Algorithms.1. IntroductionThe requirement for attitude (orientation) information of a spacecraft has been the mother of inventionof many devices and algorithms, notably the process of autonomously identifying stars (Star-ID). Thoughthere is much history of devices used to identify stars and compute an attitude that do not use a starcamera, this paper primarily analyzes algorithms that use a star camera with an imaging array and analgorithm to match observed (body) directions of stars with catalog (inertial) directions of stars withoutrequiring reorienting the camera or the spacecraft. These algorithms fall into two basic categories,