Hand-held maneuvering unit

The Hand-Held Maneuvering Unit (HHMU), also known as the maneuvering gun, or informally as "the zip gun", was the first astronaut propulsion unit. It was first used by astronaut Ed White during the first American "spacewalk", on Gemini 4, June 3, 1965. Different models of HHMU were present on Gemini 4, 8, 10, and 11, but were only used on Gemini 4 and 10. It was also used aboard Skylab. Some propellants used include oxygen, freon, and nitrogen, which are pressurized but not ignited.

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