The 2.4m-diameter cryogenic propellant tank is much lighter than a conventional metallic tank and promises to cut costs and mass of future launch vehicles.
"These successful tests mark an important milestone on the path to demonstrating the composite cryogenic tanks needed to accomplish our next generation of deep space missions," said Michael Gazarik, Nasa’s associate administrator for space technology. "This investment in game-changing space technology will help enable Nasa's exploration of deep space while directly benefiting American industrial capability in the manufacturing and use of composites."
A product of Boeing, the tank has been tested at Nasa’s Marshall Space Flight Center in Huntsville since late 2012. It underwent a series of pressurised tests designed to measure its ability to contain liquid hydrogen at extremely low temperatures. The whole tank was cooled down to -423°F and was subject to 20 pressure cycles as engineers changed the pressure up to 135psi. Nasa, together with Boeing, are already in the middle of manufacturing a larger, 5.5m tank that will be tested next year.
"This testing experience with the smaller tank is helping us perfect manufacturing and test plans for a much larger tank," said John Vickers, the cryogenic tank project manager at Marshall. "The 5.5m tank will be one of the largest composite propellant tanks ever built and will incorporate design features and manufacturing processes applicable to an 8.4m tank, the size of metal tanks found in today's large launch vehicles."
The industry representatives believe that switching from metals to composites will lead to improved performance capabilities of future systems as well as to dramatic mass reduction. The tanks might be used, for example, in the rocket upper stage of Nasa’s Space Launch System heavy-lift rocket that is currently being developed.
"The tank manufacturing process represents a number of industry breakthroughs, including automated fibre placement of oven-cured materials, fibre placement of an all-composite tank wall design that is leak-tight and a tooling approach that eliminates heavy-joints," said Dan Rivera, the Boeing cryogenic tank program manager at Marshall.
Composite tank joints, especially bolted joints, have been a particularly troubling area, prone as they are to leaks. Boeing and its partner, Janicki Industries of Sedro-Woolley, Washington, developed novel tooling to eliminate the need for heavy joints.
Cryogenic propellants are gasses chilled to sub-freezing temperatures and condensed to form highly combustible liquids, providing high-energy propulsion solutions critical to future, long-term human exploration missions beyond low-Earth orbit. Cryogenic propellants, such as liquid oxygen and liquid hydrogen, have been traditionally used to provide the enormous thrust needed for large rockets and Nasa's space shuttle.