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