Astronaut Robert L. Stewart hovering above the Shuttle Challenger (STS-10, Misson 41B) during a test of the manned manoeuvering unit, a jet propelled back pack, which enables free movement in space outside the spacecraft. Astronaut Bruce McCandless was the first man to be seen gliding freely through space propelled by the jet pack. The mission lasted from the 3rd-12th February 1984.