This is a 1:48 scale model of the Atlas-Agena B rocket. The Lockheed Missiles and Space Company began developing the Agena upper stage for the U.S. Air Force in 1956. Three versions were ultimately produced - the Agena-A, Agena-B, and Agena-D. Using modified Thor and Atlas ballistic missiles as boosters, the Agena-B launched a variety of military and civilian payloads during the early 1960s. NASA's Marshall Space Flight Center made this model and transferred it to NASM in 1972.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.