Radioisotope Power-Generating System for a Manned Space Laboratory

The results of a Douglas sponsored study of radioisotope secondary power-generating systems for space applications are presented. The study results are applicable to various space vehicles and missions requiring 4 kw or more of electrical power. The first generation of manned vehicles where a radioisotope power system is potentially applicable include the Extended Apollo and MOL type earth-orbiting laboratories. For this reason, the study results were applied to selecting a radioisotope power system for a small manned orbiting laboratory. The laboratory considered is capable of being launched in the post-1968 time period by a Titan 3C booster. An argon Brayton cycle, Dowtherm A Rankine cycle, and thermoelectric systems were investigated as possible secondary power systems capable of generating 4 kw of electrical power for the vehicle subsystem. Tradeoffs in weight, radiator-area requirement, development risk and isotope availability and cost were performed for the various systems. On the basis of the tradeoffs and the 4-kw design load, the argon Brayton cycle system was recommended.