THE GENERAL problem of non-air-breathing auxiliary power systems suitable for missiles and space vehicles is considered. On the basis of minimum weight it is shown that for powers less than a few kilowatts, systems such as batteries, fuel-cells, solar cells, and radioisotopes are preferred. The particular choice depends mainly upon the required duration.
For powers larger than a few kilowatts, either chemical propellant-mechanical conversion systems or nuclear power systems must be used. Due to shielding considerations the nuclear auxiliary power systems are primarily restricted to satellites and space vehicles. The chemical propellant systems are required for durations of a few hours and less; the nuclear systems must be used for times greater than a few hours. Various types of chemical propellant-mechanical conversion systems are described.
The problems involved in a nuclear power system are considered in detail and the characteristics of a typical advanced state-of-the-art system are described. This system operates on the Rankine-liquid-vapor condensing cycle. Thermodynamic properties are given for several fluids that might be considered for such a system.*