Lightweight, high-temperature radiators are needed for future, high-efficiency power conversion systems for Nuclear Electric Propulsion (NEP). Creare has developed flexible radiators that are extremely lightweight, stowable in small volumes, and deployable with small forces and incorporate micrometeorite protection. The present technology is limited to 350 K operating temperature due to the use of thermoplastic adhesives in the construction. In this proposal we plan to develop a high-temperature radiator panel to extend the range of operation needed for NEP systems. Our innovation is a novel material combination and fabrication method that enables radiator panels with low weight, high fin efficiency, and adequate strength at high temperature. Our lightweight radiator panel offers a factor of four reduction in weight compared with present honeycomb structures and will approach 1 kg/m?. In Phase I, we will prove the feasibility of the fabrication process and demonstrate the ability of the panel to operate at high temperature. During Phase II, we will develop a subscale radiator to demonstrate the advantages of the technology.