1984: Space Shuttle Mission 41-B began. Shuttle "Challenger" deployed "Palapa B2", and Westar 6" satellites, which were lost. Astronaut Bruce McCandless makes history when he makes the first-ever untethered extra-vehicular-activity, EVA, by using the U. S. Martin Marietta-produced Manned Maneuvering Unit (MMU) for propulsion and control. The flight lasted 7 days, 23 hours, and 17 minutes.