"Rex has been a great leader both as an astronaut and as a leader in Johnson Space Center's flight operations and safety organizations," said Johnson Space Center direct Mark Geyer. "Rex is the kind of person that has great technical background but also shows that he cares about the workforce. This made Rex particularly effective in jobs that he held at Johnson. We wish him all the best."
Walheim has served as deputy director of NASA Johnson Space Center's Safety and Mission Assurance Directorate since 2017. Walheim was appointed as an Air Force officer in 1986, where he trained to be a mechanical systems flight controller and lead operations engineer for the space shuttle landing gear, brakes and emergency runway barrier.
In 1984, Walheim was commissioned as a second lieutenant in the Air Force, then commanded the F-16 avionics and armament flight before being selected as an astronaut in 1996. He began his spaceflight career in 2002 on space shuttle Atlantis as part of STS-110.
Walheim took part in two of the mission's four spacewalks to install the International Space Station's (ISS) central truss. In addition, He was the first astronaut to use the station's Canadarm2 robotic arm. He returned to the space station in 2008 as lead spacewalker for the STS-122 mission.
Walheim's last flight was the final mission of NASA's Space Shuttle Program. The 2011 STS-135 mission delivered the last shuttle shipment of supplies, spare parts and logistics to the space station.
After STS-135, Walheim was chief of the astronaut office's exploration branch. He served as the Orion Program's astronaut representative as the new spacecraft was developed ahead of its first uncrewed flight test, Exploration Flight Test-1, in 2014.