Machining a Space Shuttle Main Engine injector, 1977

A worker drills holes in the Space Shuttle main engine's main injector body for proper size and alignment, through which propellants will pass their way into the engine's combustion chamber.

Rockwell International's Rocketdyne Division plant produced the engine under contract from Marshall Space Flight Center. This image not only gives us a glimpse into NASA's past, but also shows how far machining technology has come over the past four decades.

Each of those injector nozzles is a separate piece; What we see in the picture is the complete assembly, with each nozzle poking through the "primary plate". In all likelihood, the injectors are prefabricated with a slightly smaller size hole, which is pressed into the plate and reshaped to the final shape in this setup.

Developed by the Marshall Space Flight Center in the 1970s, the Space Shuttle Main Engine was the world's most sophisticated reusable rocket engine.

The spacecraft's three main engines operated for 8 minutes and 40 seconds with a combined output of 37 million horsepower for each shuttle flight. At its full power, this was equivalent to the output of 13 Hoover Dams.

After the solid rockets were shut down, the main engines added thrust that allowed the shuttle to reach orbit from 3,000 mph to over 17,000 mph in just six minutes. Tea

Hay produced a combined maximum thrust of over 1.2 million pounds. As the shuttle accelerated, the main engines burned half a million gallons of liquid propellant provided by the external fuel tank.

Each main engine was 14 feet (14 m) long, weighed about 7,000 pounds (3.5 tons), and had a diameter of 7.5 feet (2.4 m) at its nozzle end. It operates under temperatures ranging from -253 °C (-423 °F) to 3300 °C (6000 °F)