© 2016 American Nuclear Society. All Rights Reserved. Creare, Aerojet Rocketdyne, Sest, and the University of New Mexico Institute for Space and Nuclear Power Studies (UNM-ISNPS) are developing a turbo-Brayton power converter to support future NASA missions that use radioisotope heat sources. NASA has considered the closed Brayton cycle attractive for space since the 1960s, and Creare has developed miniature Brayton technology for nearly 40 years. Key characteristics include high specific power, high efficiency, long-life operation without wear, undetectable vibration, and flexible packaging. Preliminary design results indicate a 300 We-class converter with a turbine inlet temperature of 730°C will have a thermal-to-electric conversion efficiency greater than 25% and a specific power greater than 21 We/kg.