Jake Garn became the first U.S. sentator to fly in space on this mission of Discovery. Launch occurred at 8:59 a.m. on April 12, 1985. The crew was led by commander Karol Bobko, with pilot Don Williams, mission specialists Rhea Seddon, David Griggs and Jeff Hoffman, and payload specialists Charles Walker and Garn. The Telesat I and Syncom 4-3 satellites were deployed. Syncom's sequencer failed to initiate, however. Griggs and Hoffman conducted an unscheduled spacewalk to attached "flyswatters" on the robot arm to activate satellite's sequencer lever.