Each NMR rotor bearing in an NMR magic angle spinning assembly is constructed of a porous ceramic material and has no inlet channels or nozzles. Instead, pressurized gas is forced through pores in the bearing ceramic material from an annular groove at the bearing periphery to the central aperture. Since the pores are small and very numerous, the gas pressure is effectively balanced around the periphery of the central aperture. In addition, if contaminants block one or more pores during operation, the pores are so numerous that the balanced pressure can still be maintained in the central aperture, thereby preventing an imbalance that could destroy the rotor.