Superconducting Bearings for Space Applications

Institute for Space Systems Operations * 2001 Annual Report * 118

Superconducting Bearings for Space Applications

Researchers have demonstrated that superconducting bearings for telescope mounting can be deployed on the lunar surface, which has a cold and dusty vacuum environment, that clogs conventional mechanical bearings. High pointing precision is required of the telescope for observations requisite to advance our knowledge of the cosmos. The superconducting bearing provides an ultra-smooth rotation capability without the expenditure of energy as in magnetic bearings. The properties of the superconducting magnet bearing also allow a construction with a wide tolerance to mitigate potential problems of clogging with dust.

The project went so far as to have the bearing characterized in terms of its drag torque. This drag torque was found to have spikes as the bearing slowly turns on its axis, on top of a larger sinusoidal variation due to imperfect alignment. These observed spikes were correlated with the number of discrete pieces of superconductors used around the circumference of the bearing. This phenomenon was an unexpected discovery, detailed in the following two manuscripts:

Lee, E., K. B. Ma, T. L. Wilson, and Wei-Kan Chu. "Characterization of Superconducting Bearings for Lunar Telescopes," IEEE Trans. on Applied Superconductivity 9 (1999): 911.
-. "Superconductor-Magnet Bearings with Inherent Stability and Velocity-Independent Drag Torque," Proc., 1999 IEEE/ASME International Conference on Advanced Intelligent Mechatronics (AIM 99), Atlanta, GA, Sept. 19-23, 1999.

Vibration Isolation for Space Structures Using HTS-Magnet Interactions

A detached but interacting pair of high temperature superconductor and permanent magnets behave like a very soft spring with a relatively high level of damping due to hysteresis. Vibrations originating from sources attached to one of these components would not be transmitted to sensitive equipment attached to the other end because there is no direct physical contact between the two parts, but these components remain tied together nevertheless through magnetic flux permeating both the magnet and the superconductor. These concepts have been validated through experiments, such as those published in the following manuscript.

Yu, J. H., Y. Postrekhin, K. B. Ma, T. L. Wilson, and W.-K. Chu. "Vibration Isolation for Space Structures Using HTS Magnet Interaction," IEEE Trans. on Applied Superconductivity 9 (1999): 908.

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