Astronaut Bruce McCandless floats free above the cargo bay on February 7, 1984, during the 10th space shuttle flight (mission 41B). McCandless is propelled by the jet-powered backpack, officially known as the manned maneuvring unit (MMU), which he helped to design & which he was the first astronaut to use. Because it is not attached to the spacecraft by an umbilical cord, the MMU gives much greater mobility than was available to earlier space- walking astronauts. McCandless is holding in his hands the trunion pin attachment device (TPAD). Mission 41B was launched from the Kennedy Space Center on February 3, 1984, & landed back at Kennedy on February 12.