Manned Manoeuvring Unit MMU jet-powered backpack(On his daring mission, McCandless test-flew the Manned Manoeuvring Unit (MMU) jet-powered backpack on its first outing, propelling himself out to a distance of about 300 feet. He was in effect a separate satellite from the Shuttle, trailing in its wake as they both orbited 170 miles above the Earth at 17,400 miles per hour. He and his fellow spacewalker Robert Stewart, who flew the MMU later in the flight, earned the nicknames of the comic-book heroes Buck Rogers and Flash Gordon from their Shuttle crewmates. AllaR)
