Abstract: A limiting feature in spacecraft such as communication satellites is becoming the amount of surface such as 5, 6 available for dissipating waste heat from the electrical equipment in the satellite. The invention provides a deployable radiator 11 which carries a number of capillary pumped loops consisting of an evaporator, an outward limb and a return limb. The panel 11 is rolled up to coil the elements prior to launch, and unrolled when in orbit. The outward and return lengths of tube act as condenser for the capillary pumped loop, transport the heat over the radiating panel 11 and also provide the spring force for the panel to unroll.

Abstract: In a capillary evaporator for use in a capillary pumped loop, in which capillary action in a porous wick 7 causes cold liquid to be drawn across the wick and vaporized by a heat input structure 6 and in particular fin 8 of that structure so that the vapour passes around a loop and rejects heat at a condenser in order to cool equipment in the vicinity of the evaporator, the vapour generated in the wick 7 from the liquid/vapor interface (meniscus) 11 is subject to a lower pressure drop than hitherto by virtue of a spacer 14 of greater permeability and thermal conductivity than the wick 7 without the necessity for the meniscus 11 to recede from the fin 8 which would cause an undesirable temperature drop of the meniscus, thereby improving the capacity of the evaporator to pump liquid/vapor around the loop and thus transport heat.