These incredible photos were made on February 3, 1984, when an American astronaut Bruce McCandless II made the first untethered free flight in history. This mission marked the first checkout of the Manned Maneuvering Unit (MMU) and Manipulator Foot Restraint (MFR). McCandless made the first untethered free flight on each of the two MMUs carried on board and ventured out 320 feet (98 m) from the orbiter. At about 100 meters from the cargo bay of the space shuttle Challenger, Bruce McCandless II was further out than anyone had ever been before "free-flying" to a distance of 320 feet away from the Orbiter. Years later the NASA has decided that MMU was too dangerous for astronauts and it was never used again.