These include: Charlie Bolden, former NASA administrator, who flew on four space shuttle missions; and Nancy Currie-Gregg, who flew in four space shuttle missions, accruing 1,000 hours in space. In addition, Professor Garett Reisman spent 95 days aboard the International Space Station after which he returned to Earth aboard the Space Shuttle Discovery in 2008. Professor Paul Ronney, now AME department chair, was selected as an alternate payload specialist astronaut. His experiments flew on two Columbia Space Shuttle missions in 1997 (the mission he was backup for) and one in 2003.