 Johnson was the astronaut representative to the External Tank (ET) foam impact test team that eventually proved that ET foam debris on ascent could critically damage the shuttle's leading edge thermal protection system.In 2004, Johnson was designated as the Deputy Chief of the Astronaut Safety Branch, focusing on all aspects of Space Shuttle, ISS, and T-38 safety, with special emphasis on improving specific operational procedures and techniques to make astronauts safer in all three vehicles.In 2005, Johnson was appointed as a crew representative supporting the design and testing of NASA's newest spacecraft, the Crew Exploration Vehicle.