A comparative analysis of technical and economic efficiency of using reusable orbital transfer vehicles with nuclear electrical propulsion system and expendable chemical-propulsion upper stages in transportation operations to deliver payloads into lunar orbit

An approach is proposed for determining the efficiency of a transportation system based on a reusable orbital transfer vehicle with high-power nuclear propulsion system, which consists in using a new criterion defining the conditions for maximum efficiency of using the reusable orbital transfer vehicle. The proposed criterion is the difference between the costs of the program of missions carried out by a transportation system based on the reusable orbital transfer vehicle and by an alternative transportation system based on chemical-propulsion upper stages with liquid-propellant engines at the same total mass of payloads delivered into the target orbit. The effectiveness of applying the new criterion is illustrated using as an example the problem of payload delivery in lunar orbit and selection of design parameters for the power and propulsion system of the reusable orbital transfer vehicle.