ON 12 February 1984, Bruce McCandless waved farewell to the Challenger Space Shuttle and floated off into space. His only power was his Manned Maneuvering Unit or MMU, a nitrogen jet-propelled backpack. It was humankind’s first untethered flight in space.
Photo: Lt. Bruce McCandless, II, a flight instructor with the United States Navy and NASA’s new astronaut, is shown in 1966.
Lockheed Martin says this of its backpack:
The MMU was designed to permit astronauts to perform a variety of extravehicular activities, such as satellite retrieval, science investigations and observations, in-space construction, and rescue operations.
The MMU has been flown during three separate Space Shuttle missions. It was flight tested in February 1984 during Space Shuttle flight 41-B by astronauts Bruce McCandless and Robert Stewart. Over two days of extravehicular activity, McCandless and Stewart recorded five hours, 10 minutes of flying time on the two on-board MMUs.
Photo: The crew for the Space Shuttle challenger leaves for Pad 39A and their scheduled 8 am liftoff at the Kennedy Space Center on Friday, Feb. 3, 1984. In front is Commander Vance D. Brand. He is followed by from left, Mission Specialist Bruce McCandless; Mission Specialist Robert L. Stewart; Mission Specialist Robert E. McNair and Pilot Robert L. Gibson.
The Smithsonian adds:
The MMU had 24 small gaseous nitrogen thrusters and was operated with hand controllers on the arms of the unit.
On February 7, 1984, on Space Shuttle mission STS 41-B, astronaut Bruce McCandless tested this MMU, serial number 3. He made the first untethered spacewalk as he flew some 300 feet from the Shuttle.
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