Country of Origin: United States of America
Overall: 2ft 9in. x 2ft 1 1/4in. x 11in. (83.82 x 64.14 x 27.94cm)
Box, overall, exterior, composite; nozzles, non-ferrous metal; brass mounting brackets on each corner of box; screws, probably aluminum; tops of motors, underneath box, steel; plastic insulated electrical wires underneath box
This is a quad, or cluster, of four Apollo Reaction Control System (RCS) engines. The RCS was a vital rocket engine system for maintaining the attitude of the Apollo Service Module (SM), helped it to maneuver in space, plus undertake minor midcourse velocity corrections, abort separations and emergency attitude maneuvers. Each thruster produced 100 pounds of thrust. The propellants were monomethyl hydrazine (MMH) and nitrogen tetroxide. The quad shown here was not flown but was from Apollo-Soyuz Test Project, possibly as a backup RCS. It was transferred to the Smithsonian in 1980 from the NASA Johnson Space Flight Center.