Funds are provided to support an investigation of the phenomena that take place when fluids are injected into a high vacuum an area in which there have been very few quantitative studies which is surprising since there are a large number of scientific and commercial applications of these phenomena. The study proposed here is directed at developing a quantitative understanding of the interactions between the fluid mechanics, cavitation and surface characteristics of liquid streams injected into a high vacuum. The work involves experiments in unique facilities that have been designed for this type of study, along with sufficient analyses and modelling to accomplish the purposes of developing a quantitative understanding of the phenomena.