This is a full-scale reproduction of the Jupiter-C launch vehicle built by the Reynolds Metals Company. It has a replica of the Explorer I satellite on top. The Jupiter-C launched the Explorer I on January 31, 1958 as the U.S.'s first artificial satellite.
The Jupiter-C was a modified Army Redstone liquid-fuel rocket with solid-fuel upper stages and a slightly more powerful main stage engine. The Explorer 1 instruments recorded cosmic rays, micrometeorites, temperatures, and radiations. This rocket was transferred to the Smithsonian by the Army in 1959.