Garneau was one of the first Canadian Astronauts and he became the first Canadian in outer space in October 1984. In 1984, he was seconded to the new Canadian Astronaut Program (CAP), one of six chosen from over 4,000 applicants. He flew on the shuttle Challenger, STS-41-G from October 5 to 13, 1984, as payload specialist. He was promoted to Captain in 1986, and left the Navy in 1989, to become deputy director of the CAP. In 1992-93, he underwent further training to become a mission specialist. He worked as CAPCOM for a number of shuttle flights and was on two further flights himself - STS-77 (May 19 to 29, 1996) and STS-97 (to the ISS, November 30 to December 11, 2000). He has logged over 677 hours in space.