Space Shuttle program: Space Shuttle Challenger makes its maiden voyage into space on STS-6.

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 Space Transportation System (STS), taken from a 1969 plan for a system of reusable spacecraft where it was the only item funded for development, as a proposed nuclear shuttle in the plan was cancelled in 1972. It flew 135 missions and carried 355 astronauts from 16 countries, many on multiple trips.

Space Shuttle Challenger (OV-099) was a Space Shuttle orbiter manufactured by Rockwell International and operated by NASA. Named after the commanding ship of a nineteenth-century scientific expedition that traveled the world, Challenger was the second Space Shuttle orbiter to fly into space after Columbia, and launched on its maiden flight in April 1983. It was destroyed in January 1986 soon after launch in a disaster that killed all seven crewmembers aboard.

STS-6 was the sixth NASA Space Shuttle mission and the maiden flight of the Space Shuttle Challenger. Launched from Kennedy Space Center on April 4, 1983, the mission deployed the first Tracking and Data Relay Satellite, TDRS-1, into orbit, before landing at Edwards Air Force Base on April 9, 1983. STS-6 was the first Space Shuttle mission during which a Extravehicular activity was conducted, and hence was the first in which the Extravehicular Mobility Unit (EMU) was used.

April 4 is the 94th day of the year in the Gregorian calendar; 271 days remain until the end of the year.