System for determining the position of a spacecraft using a sun sensor, an earth sensor and a space-earth connection

摘要

A system is described for determining a three-axis attitude measurement of a spacecraft (10). The spacecraft (10) includes a spacecraft body (18) having pitch (P), roll (R), and yaw (Y) axes, means (12, 24, 28) for receiving signals indicative of spacecraft operating conditions, a processor (32) for generating command signals based on the operating conditions, an Earth sensor (12) disposed within the spacecraft body (18) for creating attitude reference signals indicative of a roll-axis attitude and a pitch-axis attitude, and means (14, 20, 28, 30) for generating error signals indicative of an azimuth attitude error and an elevation attitude error with respect to a first target ground station, the generating means (14, 20, 28, 30) being disposed within the spacecraft body (18). The system comprises a sun sensor (16) mounted on the spacecraft body (18) and in communication with the processor (32), the sun sensor (16) having a predetermined field-of-view and being operative to create sun sensor signals indicative of a pitch-axis attitude and a yaw-axis attitude, while the sun is within the field-of-view; and means (32) for combining a plurality of signals selected from the group consisting of the attitude reference signals, the sun sensor signals, and the error signals, so as to determine a three-axis attitude measurement of the spacecraft (10). IMAGE