Bob Behnken is a NASA astronaut, engineer, and former Chief of the Astronaut Office. Behnken holds a Ph.D in mechanical engineering and the rank of colonel in the U.S. Air Force, where he served before joining NASA in 2000. He flew aboard Space Shuttle missions STS-123 (2008) and STS-130 (2010) as a mission specialist, accumulating over 708 hours in space, including 37 hours of spacewalk time. He is married to fellow astronaut K. Megan McArthur.Following retirement of the Space Shuttle, Behnken was Chief of the Astronaut Office from 2012 to 2015. Assigned to the SpaceX Dragon Capsule in 2018 as part of NASA's Commercial Crew Program, Behnken was scheduled to launch aboard the spacecraft's first crewed mission with fellow astronaut Doug Hurley on May 27, 2020. The mission, Crew Dragon Demo-2, will take Behnken and Hurley to the International Space Station, where they will dock and stay for several weeks. The launch was cancelled 16 minutes and 54 seconds before takeoff, due to bad weather. The mission was postponed and scheduled to Saturday, May 30, at 19:22 UTC.