Abstract: A method and arrangement for aligning a space vehicle with respect to a reference object is disclosed. A measuring direction is obtained by determining the angular orientation direction of the space vehicle with respect to the reference object and subsequently the space vehicle is aligned by means of actuators such that the measuring direction corresponds to a reference direction on the space vehicle. The actuators are driven by control signals which are derived from the measuring direction to cause control torques on the space vehicle. The orientation of the space vehicle and reference object is determined only with respect to a single measuring direction along a main axis of a direction sensor.

Abstract: This method serves for calibrating gyros forming part of the attitude control system of a satellite stabilized in three axes and which have an unknown drift. A two-axis sensor measuring the direction of a radiating reference object in the coordinate system x, y, z fixed with respect to the satellite is used. Two reference attitudes each different with respect to the reference object are commanded to the satellite in the course of two consecutive time intervals spaced from each other. The values measured by the sensor representing the respective actual direction of the reference object are recorded at the start and at the end of the time intervals. The respective time integrals of the gyro output signals are computed during the time intervals, which represent the gyro drift plus the respective instantaneous satellite deviation from the commanded reference attitude. Finally the gyro drift is determined from these time integrals and the values measured by the sensor.

Abstract: A method of sun and earth acquisition for satellites which are stabilized in three dimensions and are equipped with acquisition sensors is provided. The method enables the acquisition of the earth and sun to be concluded as quickly as possible. The method includes a series of cumulative or alternative steps for changing the attitude of the satellite relative to the sun. These attitude changes are governed by a simple set of control equations. An arrangement for effecting the method is also provided.