Abstract: An orbital system comprising a main platform and a satellite tethered by a long cable which may be used to perform measurements in the upper layers of the atmosphere. Air drag on the satellite causes the orbit parameters to decay, and means of regenerating the orbit parameters by electro-dynamic propulsion are provided. The cable is electrically conductive and, in a propulsion configuration, a current is passed through the cable to provide electro-geomagnetic thrust. Winches enable the cable to be wound in and out, either constantly, or in synchronization with angular oscillation of the system to damp the oscillations.On an east-bound orbit, the satellite may be transferred from a measurement configuration, where it is below the platform, to a propulsion configuration, where it is above the platform. This is achieved by winding the cable in synchronism to excite the oscillations until it swings above the platform and then to damp the oscillations so that it remains above the platform.

Abstract: The nutation damper comprises a closed flow path for a dense liquid, which may be a propellent and a pump for setting the liquid in periodic motion, thereby to dissipate or generate rotational energy controlled by a detector sensitive to a parameter relating to the nutation angle, according to the law of conservation of angular momentum. The principal application of the device is to the nutation damping of spinning spacecraft, in which the ratio between the moment of inertia about the spin axis and the lateral moment inertia is greater or less than 1.