A bearing assembly for stabilizing rotation of a rotatable element includes a gas bearing acting as a bearing for the rotatable element. An ultrasonic vibration pump is coupled to the gas bearing for providing pressurized gas to the gas bearing, and a sealed housing encloses the gas bearing and the ultrasonic vibration pump. Also described is a reaction wheel assembly for a spacecraft. The reaction wheel assembly includes a reaction wheel and the bearing assembly for stabilizing rotation of the reaction wheel.