STS-41-B was the tenth NASA Space Shuttle mission, launching on 3 February 1984 and landing on 11 February. It was the fourth flight of the Space Shuttle Challenger. Following STS-9, the flight numbering system for the Space Shuttle program was changed. Thus, the next flight, instead of being designated STS-11, became STS 41-B; the original successor to STS-9, STS-10, was cancelled due to payload delays.

Challenger lifted off from Kennedy Space Center at 8 am EST on 3 February 1984. Two communications satellites were deployed about 8 hours after launch; one, WESTAR, was for Western Union, and the other, Palapa B-2, for Indonesia. However, the Payload Assist Modules (PAM) for both satellites malfunctioned, placing them into a lower-than-planned orbit. Both satellites were retrieved successfully the following November, during STS-51-A, by the orbiter Discovery.

The STS 41-B crew included commander Vance D. Brand, making his second Shuttle flight; pilot Robert L. Gibson; and mission specialists Bruce McCandless II, Ronald E. McNair and Robert L. Stewart.