Astronaut Bruce McCandless on the first spacewalk using MMU, 1984.
© National Aeronautics & Space Administration / Science & Society
Cutout of Bruce McCandless on the first spacewalk using MMU. The Manned Manoeuvring Unit (MMU) has small gas thrusters which enable an astronaut to move around outside the Space Shuttle without a tether. This was first flown by McCandless on the Space Shuttle Challenger 41-B (STS-10) mission in February 1984.