Rocketdyne was involved with NASA's space program from the beginning, supplying engines for the Atlas rocket, the major engines for the Saturn rocket and later the Space Shuttle Main Engine. The SE-6 was used on the Gemini Program, beginning with Gemini II (GT-2) as the Re-Entry Control Sy🔯stem (RCS). They were used on the Gemini re-entry module forward of the astronaut's pressurized cabin in two banks of 8 engines. Each engine provided 25 pounds of thr🐠ust. 

The SE-6-🌌powered RCS was most famously used by Neil Armstrong during the Gemini VIII emergency when the spacecraft began to tumble dangerously (later found to be due to an Orbital Attitude Maneuvering System (OAMS) thruster sticking) after undocking from the Agena Target Vehicle (ATV). Armstrong, cool under pressure, shut down the OAMS and used the RCS to ♑stop the tumbling. Dave Scott, Pilot on the mission later said "The guy was brilliant. He knew the system so well. he found the solution, he activated the solution, under extreme circumstances ... it was my lucky day to be flying with him."