Precise Pointing of Cubesat Telescopes: Comparison between Heat and Light Induced Attitude Control Methods

CubeSats are emerging as low-cost tools to perform astronomy, exoplanet searches and earth observation. These satellites can target an object for science observation for weeks on end. This is typically not possible on larger missions where usage time is shared. The problem of designing an attitude control system for CubeSat telescopes is very challenging because current choice of actuators such as reaction-wheels and magnetorquers can induce jitter on the spacecraft due to moving mechanical parts and due to external disturbances. These telescopes may contain cryo-pumps and servos that introduce additional vibrations. A better solution is required. In our paper, we analyze the feasibility of utilizing solar radiation pressure (SRP) and radiometric force to achieve precise attitude control. Our studies show radiometric actuators to be a viable method to achieve precise pointing. The device uses 8 thin vanes of different temperatures placed in a near-vacuum chamber. These chambers contain trace quantities of lightweight, inert gasses like argon. The temperature gradient across the vanes causes the gas molecules to strike the vanes differently and thus inducing a force. By controlling these forces, it’s possible to produce a torque to precisely point or spin a spacecraft. We present a conceptual design of a CubeSat that is equipped with these actuators. We then analyze the potential slew maneuver and slew rates possible with these actuators by simulating their performance. Our analytical and simulation results point towards a promising pathway for laboratory testing of this technology and demonstration of this technology in space.