Scientists launched an investigation called the Constrained Vapor Bubble, or CVB, to the International Space Station to look into the operation of a heat pipe in space. The Constrained Vapor Bubble is the prototype for a wickless heat pipe and is the first full-scale fluids study in the Fluids Integrated Rack or FIR facility flown on the U.S. module of the space station.
Nearly all heat pipes contain wicks or grooves that enhance capillary action and promote the pumping of the working liquid from the cool liquid pool back to the hot surface where the liquid can evaporate again. Heat pipes built without wicks hold open the possibility of significant weight savings for space flight.
Learn more from NASA.