This is a copper water jacket used for cooling rocket motors and was designed and built by early American rocket pioneer Dr. Robert H. Goddard. If a rocket motor became too hot or overheated during runs, it could burst or explode. The jacket fit snugly around the entire motor from the top of the combustion chamber to the bottom of the long nozzle.The jacket was first tried in tests in 1931 and appeared to work. Goddard thus used this type of cooling in many of his rockets up to 1941. He came close to developing a regenerative cooling system in which the fuel circulates around the chamber before it is injected into the combustion chamber but preferred to use the water jacket. This object was donated to the Smithsonian by Mrs. R. H. Goddard in 1959.