It is demonstrated that the system mass required for radiation of (waste) heat from a thermal source to space can be reduced by rejecting the heat from a radiator at a temperature above that of the thermal source, using a heat cycle powered by a second heat source at a higher temperature than that of the source of waste heat. For temperature ratios of the second-to-first source on the order of 5, the total radiator area is reduced by a factor of 16 for Carnot cycles. Practical heat cycles may yield reductions as large as a factor of 10.