This is a cutaway of a 25-pound thrust Gemini Reentry Control System (RCS) thruster. This thruster flew on Gemini VIII, launched on 16 March 1966 with astronauts Neil Armstrong and David Scott. The launch went smoothly but a major problem developed after docking of the spacecraft with the Gemini Agena Target Vehicle, when a spacecraft OAMS thruster malfunctioned. The crew undocked from the Agena and brought the spacecraft under control by deactivating the OAMS and using the reentry control system (RCS) to reduce the spacecraft's rapid rotation. Premature use of the RCS, however, required the mission to be terminated early. Armstrong and Scott landed safely in the Pacific Ocean on 17 March 1966.
This object is half of one of the RCS thrusters in the nose of Gemini VIII encased in a block of Lucite. By 1969, the Smithsonian Institution's National Collection held both the thruster and the Gemini VIII capsule.