The characteristics of Rankine space power plants in the zero gravity aspect of the environment of space were lnvestigated. The expected effects of Rankine space power plants are described. Discussions of experimental techniques for studying these phenomena show that this information can be obtained rapidly and economically. Recommendations for a program to supplement SNAP II and slmllar Ranklne space power development efforts in this vital area are made, and consist of: the development and testing of a small system that adequately simulates a complete Ranklne system, first in zero grayity and finally, in the complete orbltal environment; followed by, the development and similar testing of a complete Rankine system using SNAP ll hardware. (auth)