On board the space shuttle Discovery in March 1989, he became the first person to inject the drug Phenergan to treat space sickness, a treatment now used by NASA. His second shuttle mission, in June 1991, was aboard the first dedicated space and life-science mission, Spacelab Life Sciences (SLS-1), to monitor physical reactions to microgravity. Bagian became an astronaut in 1980 and left NASA in 1995.