STS-41B

STS-41B was Challenger's fourth flight and a Space Shuttle mission launched from Kennedy Space Center on February 3, 1984. The five-person crew was commander Vance Brand, pilot Robert L. Gibson, and mission specialists Bruce McCandless II, Ronald McNair, and Robert Lee Stewart. McCandless and Stewart performed the first untethered spacewalks, using the Manned Maneuvering Unit to fly free of the orbiter and return under their own control. The mission deployed the Westar VI and Palapa B2 communications satellites, but both were left in unusable low orbits after their PAM-D upper stages failed. Challenger landed at Kennedy's Shuttle Landing Facility on February 11, the first Shuttle landing at KSC after an orbital mission.