The tenth mission of the space shuttle program was flown by Challenger. Liftoff was at 8:00 a.m. on February 3, 1984 from pad 39A at Kennedy Space Center. Commander Vance Brand, pilot Hoot Gibson and mission specialists Bruce McCandless, Ron McNair and Robert Stewart deployed the commercial Westar 6 and Palapa B2 communications satellites. However, the crafts' kick motors malfunctioned. McCandless and Stewart conducted the first untethered spacewalks using the Manned Maneuvering Unit.