Why do standard commercially available motors fail in a vacuum?
Commercial motors are designed for lowest cost, without consideration of possible use in a vacuum. Glues, insulation s, varnishes, greases and other materials selected for lowest cost, typically evaporate or outgas very quickly in a vacuum. In addition special attention needs to be given to open connections to prevent arcing when the insulation effects of air are removed. Finally, without the cooling medium of air, the motors run hotter than normal, the higher temperatures lead to rapid failure.
