His four space shuttle flights include the Discovery mission in February 1997 to service the Hubble Space Telescope. During the mission he made two space walks. Tanner’s last mission was on the crew of Atlantis in September 2006, which successfully restarted assembly of the International Space Station. He logged more than 1 069 hours in space and over 46 hours of space walks. Tanner joined NASA's Johnson Space Center in 1984 as an aerospace engineer and research pilot. He was selected as an astronaut in 1992 and retired from NASA in 2008.