This is part of an Atlas missile or rocket airframe that survived reentry into the Earth's atmosphere. It is not known what exact vehicle it came from or when or where it impacted. The Atlas was America's first intercontinental-range ballistic missile, deployed in the late 1950s and early 1960s. It was then modified by the National Aeronautics and Space Administration to launch the Project Mercury manned capsules into Earth orbit during 1961-1962. Beginning in the early 1960s, Atlas first stages were also mated with a variety of upper stages to launch numerous civilian and military payloads into space. Convair made the Atlas and the Smithsonian Astrophysical Observatory transferred this fragment to NASM in 1971.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.