Space Shuttle program: STS-41-B Mission: astronauts Bruce McCandless II and Robert L. Stewart make the first untethered space walk using the Manned Maneuvering Unit (MMU).

The Space Shuttle program was the fourth human spaceflight program carried out by the U.S. National Aeronautics and Space Administration (NASA), which accomplished routine transportation for Earth-to-orbit crew and cargo from 1981 to 2011. Its official program name was carried over from the 1969 plan for the Space Transportation System (STS) of reusable spacecraft. Only the shuttle and supporting rockets were funded for development; a proposed nuclear lunar shuttle in the plan was canceled in 1972. It flew 135 missions and carried 355 astronauts from 16 countries, many on multiple trips.