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For years dating back to the Gemini missions back in the 60’s, astronauts had opened the hatch of their spacecraft and taken space walks.  But every time they walked out into space they were always  tethered – kind of a long umbilical cord that not only had air, electric and communication lines, but insured that the astronauts wouldn’t float away 170 miles above the Earth. 

Everything changed when astronaut Bruce McCandless became the first human being to fly untethered in space when he left the space shuttle Challenger and maneuvered around the space shuttle with a rocket pack that he designed.

So there he was orbiting around the earth along with the shuttle at a speed of more than 17,500 miles an hour and at times moving as far as the length of a football field away from the shuttle.  After an hour and a half flying around, testing the backpack and taking pictures of Earth, McCandless climbed back inside.

A few hours later, astronaut Robert Stewart did the same thing and on later missions it was used to repair and maintain satellites and to put together pieces of space stations.  That first untethered space walk happened on this date in 1984.

SOURCE: HistoryChannel