Authors: Daan Stevenson; Hanspeter Schaub
Addresses: University of Colorado, 431 UCB, Boulder, CO 80309, USA ' University of Colorado, 431 UCB, Boulder, CO 80309, USA
Abstract: A terrestrial testbed designed to investigate the torques between non-symmetric charged bodies is introduced. In practice, these torques may be used by spacecraft for touchless remote attitude control. The experimental system consists of a charged cylinder that rotates about its minor axis on a low friction bearing, while the electric potential on a nearby sphere is actively controlled to increase or decrease the rotation rate of the cylinder. A numerical simulation of the system that uses a previously developed reduced order electrostatic model is found to match the experimental data extremely well. Time dependent charge drain and disturbance torques on the cylinder are characterised so that they may be accurately modelled in the simulation. At low speeds, the achievable Coulomb torques are several times higher than the atmospheric drag and bearing friction. An active charge control de-spin manoeuvre arrests the cylinder motion in about 1/3 of the time it takes the cylinder to come to rest due to the friction in the system alone. Several hardware components and methods are identified for improvement in future iterations of the testbed, but the current result constitutes a successful verification of the Coulomb spacecraft de-spin concept.
Keywords: spacecraft Coulomb charging; remote attitude control; rotational testbed; rotation control; numerical simulation; reduced order electrostatic modelling; time dependent charge drain; disturbance torques; Coulomb torques; atmospheric drag; bearing friction; charge control de-spin; friction; Coulomb spacecraft de-spin.
International Journal of Space Science and Engineering, 2014 Vol.2 No.1, pp.96 - 112
Received: 23 Jun 2013
Accepted: 26 Sep 2013
Published online: 13 May 2014 *