Heat pipes developed at Los Alamos National Lab efficiently transport large quantities of heat in numerous applications, including space flight. Fluid within the heat pipe vaporizes at the hot end; condenses as it reaches the other, slightly cooler end; and returns to the hot end through a capillary wick to repeat the process. "It's a little like a laboratory in a tube," says Bob Reid, a mechanical engineer in Los Alamos Engineering Science and Applications Div. He believes the heat pipe technology is destined to be an integral part of space-age travel. NASA's Marshall Space Flight Center (Huntsville, AL) is working with Los Alamos developing heat pipes for use in nuclear reactors to produce propulsion and generate electricity for spacecraft journeying through the solar system. Los Alamos also worked with NASA Langely Research Center (Hampton, VA) designing a futuristic hypersonic aerospace plane that would complete most of its flight in low-Earth orbit. Heat pipes cool the leading edges of the wings and engine ducts. Heat pipes also flew aboard the Space Shuttle Endeavor. Additional applications include miniature versions of the heat pipe that cool the chips inside laptop computers and geostationary communications satellites. Heat pipes vary greatly in size, depending upon their particular use. Some are the size of hypodermic needles. Other versions stretch to 24 ft. The heat pipes use lithium, a soft chemical that is the lightest known metal. Visit the Los Alamos web site, www.lanl.gov .