Radiators will be used on Mars to reject excess heat from various processes and surfaces and will help temper the climate of any future manned habitats. Radiator performance is a function of the radiator size (area), the emissivity, ε, of the radiator surface, the radiator temperature, local environmental conditions, and the effective sky temperature to which it radiates. The effective sky temperature of Mars is not known. Previous estimates have ranged between 80 K to 170 K. Also, it is not known how dust accumulation and other environmental effects act to change the performance of a radiator as a function of time. The MTERC Experiment is designed to gather data to address these unknowns. This paper will describe the operational theory and the configuration of the MTERC experiment hardware and will discuss results of MTERC performance testing.