Abstract: Device for aligning the roll axis of a rotating artificial satellite having radial solar panels equipped with angularly movable control surfaces at their extremities. The device includes a motor associated with each control surface for controlling the angle of the control surface with respect to the solar panel, each motor being actuated by a current which is dependent on the displacement of the roll axis from a desired position and which varies cyclically during the rotation of the satellite. The motor also includes a detector for detecting the angular speed of movement of the control surface and introducing a damping effect.

Abstract: A correction method for transverse defocussing of paraboloid oriented relative to the source initially aligned with the focus consists of securing said paraboloid to first platform, articulating said first platform through hinge means jointed to second platform, itself articulated through further hinge means jointed to a stationary part, and then orienting said hinge means to said focus, while providing moving means for said platforms, said moving means being servocontrolled responsive to pointing error detector thereby to hold permanently said focus close to the source.Provision is also made of a parabolic antenna comprising means for carrying out said method. The system is applied to radio and TV broadcast apparatus aboard satellites.

Abstract: The present invention relates to the orientation of antennae on a satellite possessing at least one antenna comprising a horn rigidly connected to the body of the satellite, a movable reflector mounted on an orientable platform and at least one radio-frequency sensor in the horn using said antenna to control the orientation of said reflector. The invention consists of: using a signal characterizing the pivoting of the orientable platform with respect to the body of the satellite to orient said satellite correctly with respect to the reflector in order to limit the pivoting of said platform; using the signals from at least one earth sensor in the same way as the signals from the radio-frequency sensor to control said reflector, so as to orient the beam towards the point sighted on the earth. The invention is particularly useful for the control of the orientation of antennae, particularly on a satellite.

Abstract: Electromagnetic method and apparatus to accurately control the orientation of a platform according to two axes wherein pivoting of the platform about two orthogonal axes passing through its center is effected by electromagnetic means, with the servo-control being obtained by using a detector responsive to the angle of deviation from a reference direction, an amplifier, a low-pass filter, a phase lead filter and power amplifiers supplying currents to the electromagnetic devices. The method and apparatus is particularly adapted to the orientation of platforms carrying means such as aerials or inertia wheels intended for piloting a space vehicle.