This proposal describes a research project to develop a freezable radiator for space systems where the heat loads and dissipation requirements are time-varying. The proposed approach is expected to lead to radiator designs with significantly lower size and weight compared to current systems. During the Phase I studies, a theoretical model will be developed in order to provide a basis for the design of the proposed radiator. This will be combined with experimental studies to verify/evaluate the practical feasibility of various designs. Manufacturing and systems issues will also be evaluated as part of the Phase I research. POTENTIAL COMMERCIAL APPLICATIONS Lightweight, compact, freezable space radiators are critical in reducing costs related to space transportation of future satellites and other space systems. The proposed approach is also applicable for heat sinks for electronic components which have enormous commercial applications.