STS-41-B was NASA's tenth Space Shuttle mission and the fourth flight of the Space Shuttle Challenger. It launched on February 3, 1984 and landed on February 11, 1984, after deploying two communications satellites. It was also notable for including the first untethered spacewalk.
Following STS-9, the flight numbering system for the Space Shuttle program was changed. Because the original successor to STS-9, STS-10, was canceled due to payload delays, the next flight, originally and internally designated STS-11, became STS-41-B as part of the new numbering system.