Detumbling large space debris via laser ablation

This paper presents an approach to control the rotational motion of large space debris (the target) before the spacecraft starts deflecting its trajectory through laser ablation. A rotational control strategy based on the instantaneous angular velocity of the target is presented. The aim is to impart the maximum control torque in the direction of the instantaneous angular velocity while minimizing the undesired control components in the other directions. An on-board state estimation and control algorithm is then implemented. It simultaneously provides an optimal control of the rotational motion of the target through the combination of a LIDAR and a navigation camera. The instantaneous angular velocity of the debris is estimated through the application of the optic flow technique. The whole control and estimation technique is applied to the case of cylindrical and parallelepiped shapes as representative of upper stages and spacecraft. When applied to the cylindrical shape, results show that the control strategy and laser technique fail to control along three directions unless the geometrical axes are different from the inertial ones. In general the thrust vector is aligned with the normal to the local surface meaning that no control torque can be exerted along the longitudinal axis in the case of an ideal cylinder.