RTI proposes to develop an efficient, reliable, compact and lightweight heat pump for space applications. The proposed effort is expected to lead to (at the end of Phase II) a microclimate system that can remove 300 Watts of heat (in the cooling mode) requiring 92 Watts of electrical power. In the heating mode, the same system would provide up to 392 Watts of heat. The system is expected to weigh around 3.5 pounds (not including the power source) within a volume of about 1000 cc or 1 L. The design is based on a recently developed portable cooler for the Army. The performance of this system cannot be matched simply by using smaller versions of conventional designs, and is accomplished with recent advances in miniaturization and MEMS. Key technological innovations include use of a Wankel compressor with solid lubricants, system configuration for compact design, and design of condenser and evaporator for microgravity application. Phase I effort will concentrate on thermodynamic cycle, compressor, and solid lubrication. Design of the rest of the system, components and system testing and system integration would be undertaken in Phase II.