Dynamics of a High-Agility, Low-Power Coelostat Telescope

Control-moment gyroscopes (CMGs) are power-efficient attitude-control actuators that produce high torques for agile spacecraft. We propose the use of CMGs in actuating joint degrees of freedom in a spacecraft-mounted agile coelostat telescope, whose tasks include acquiring and tracking a high-speed target. High agility, on the order of several radians per second, is a priority for such a system; however, such capabilities are achieved with traditional actuators only at the expense of excessively high electrical power. The proposed design provides reactionless, agile slewing of a telescope for a small fraction of the power required by fixed rotors in a reaction wheel assembly. This study provides explicit equations of motion for the proposed system and demonstrates by simulation that a CMG-driven system offers the same agility with less than 10% of the power of a telescope actuated by reaction wheels.