Three axis earth/star sensor

摘要

An earth sensor primarily for use at geosynchronous altitude measures Pitch, Roll, as well as Yaw. Pitch and Roll are obtained from the sun illuminated earth crescent viewed through a pinhole by a CID video camera. A circular mask positioned in front of the pinhole blacks out the center 10 degrees of the earth. A beam splitter receives visible radiation from the earth crescent through the pinhole and combines it with energy from a lens system aimed at Polaris and beta Ursa Minor and/or gamma Cepheus and projects radiation from such polar stars onto the CID detector. Yaw is obtained by sensing the position of the pole star Polaris.