This paper describes the current state of knowledge of the rotating fluidized bed reactor for space power and propulsion application. The results of typical calculations of the thermofluid behavior are given showing how reactor parametrics affect the power level and size of the reactor. Thermal stress analysis of the blind-end plate of the engine chamber has shown the need for creative design effort to preclude failure. Coupled thermofluid-neutronic stability analysis including the effects of the expanding particulate fuel bed indicate adequate stability margins which are, nevertheless, orders of magnitude less than those for the equivalent fixed bed reactor. The overall design concept appears capable of providing very high power density propulsion with powers in the range of 250-5000 MW or larger. This concept thus appears to be enabling for short-time missions including LEO-to-GEO interorbital transfer, lunar, or interplanetary transport at 1-g.