Astronaut Robert L. Stewart in a manned manoeuvering unit, or jet propelled back pack, during the first trials of the unit on the 10th shuttle mission. Shuttle Challenger (STS-10) was launched from Kennedy Space Centre, Florida on the 3rd February & returned to Edwards Air Force Base, California on 12th February 1984. The jet propelled back pack enabled the astronauts to leave the spacecraft & float freely in space without the use of safety lines.