Flat-spin recovery of spinning satellites by an equatorial torque

The recovery from a flat-spin motion represents one of the most impressive practical applications in the field of spinning-satellite dynamics. The present paper presents flat-spin recovery maneuvers by means of a body-fixed torque within the plane perpendicular to the maximum principal axis of inertia. The conditions for a successful recovery are established. These are quite different from those obtained in the case when the torque is along the minimum axis of inertia where a minimum torque level is required for a successful recovery. If the torque component along the intermediate axis is negative, a recovery from a pure flat spin can be established for any torque magnitude. However, the time to recovery increases indefinitely when this torque component approaches zero. During the recovery maneuver, the angular velocity and angular momentum vectors become aligned with the minimum axis of inertia by turning over about 90° in the body frame. In inertial space, however, the angular momentum stays in the vicinity of its orientation before the start of the recovery.