For future space projects such as Earth orbiting platforms, space stations but also Moon or Mars bases, the need to manage waste heat rtp to 100 kW has been identified. For this purpose large heat pipe radiators have been proposed with heat pipe lengths of 15 m and heat transport capabilities up to 4 kW: It is demonstrated that conventional axially grooved heat pipes can be improved to provide 1 kWm heat transport capability. Higher heat loads can be handled only by high-composite wick designs with large liquid cross sections and circumferential grooves in the evaporator. With these high-performance heat pipes, heat transfer coefficients of about 200 kW/m(2) K and transport capabilities of 2 kW over 15 m can be reached. Configurations with liquid fillets and axially tapered liquid channels are proposed to improve the ability of the highly composite wick to prime.