Preliminary design studies show that a low-power, turbomachine-based, Brayton-cycle power unit is an extremely attractive option for thermal-to-electric power conversion on long-duration, deep-space missions. A 100 We power unit promises to achieve a thermal efficiency of 38% and weigh only 2.4 kg while requiring a single general-purpose heat source. The design of this unit is based on miniature, high-performance components that have been developed by Creare Inc. for space-borne, Brayton-cycle refrigerators. The components include high-speed, high-efficiency rotors and alternators: high-speed, precision gas bearings, and high-performance, compact recuperators. Miniaturization and performance goals for these components have been achieved through unique microscale fabrication techniques that have enabled high precision in miniature components. The resulting refrigerators are lightweight, highly efficient, vibration-free, highly reliable, and have long, maintenance-free life (greater than 5 years). These ref...