Even during the earliest years of America’s manned space program, NASA understood that technology was needed to allow astronauts to move and work beyond the confines of their spacecraft. During the mid-60s, the Vought Corporation developed a self-propelled backpack known as the Extravehicular Maneuvering Unit (EMU) – sometimes called the Manned Maneuvering Unit (MMU) – that would allow an astronaut to operate independently for several hours. Versions of the EMU were carried aboard Gemini flights 8 and 9 in 1966, but because of time constraints, they were never tested. Although EMU’s were tested within the Skylab space station in the mid-1970s, it wouldn’t be until the Space Shuttle program of the 1980’s that the EMU/MMU finally became a familiar and essential tool in America’s conquest of space.