Past work has shown that Brayton power converters are an attractive option for high power, long‐duration space missions. More recently, Creare has shown that Brayton technology could be scaled with high efficiency and specific power to lower power levels suitable for radioisotope power conversion systems. Creare is currently leading the development of an advanced turbo‐Brayton converter under NASA’s Prometheus Program. The converter design is based on space‐proven cryocooler technologies that have been shown to be safe; to provide long, maintenance‐free lifetimes; and to have high reliability, negligible vibration emittance, and low EMI/EMC. The predicted performance of a converter at the beginning of life is greater than 20% (including electronic inefficiencies and overhead) with a converter specific power of greater than 8 We/kg for a test unit and greater than 15 We/kg for a flight unit. The degradation in performance over a 14‐year mission lifetime is predicted to be negligible, and the primary life l...