Novel hybrid-wick aluminum and stainless-steel/ammonia constant conductance heat pipes (CCHPs) were developed to operate in space carrying power over long distances, as well as act as a thermosyphon on the planetary surface for lunar and Martian landers and rovers. These hybrid-wick heat pipes have a sintered wick in the evaporator and a standard grooved wick in the condenser. The Thermal Link planetary CCHP with small sintered nickel particles transported approximately one-half of the power transported by the CCHP with large sintered nickel particles at 0.1 in. against gravity. However, the CCHP with large sintered nickel particles transported three to four times higher power than the CCHP with small sintered nickel particles at higher inclinations (0.3 in.) for both stainless-steel and aluminum heat pipes.