Astronaut and flight surgeon who first joined NASA in 2007. He became a member of NASA Astronaut Group 20 in 2009 and would become a crew member on the International Space Station in 2015.
After entering the United States Air Force Academy, he would later go on to earn a degree in biology. He would also earn a master's in cardiovascular physiology from Colorado State University and a doctorate of medicine at the University of Colorado.
Outside his work as an astronaut, he has also worked with the Spacecraft Communicator and Extravehicular Activity branches of NASA.
Born in Taiwan, he moved to the U.S. soon after, though he spent most of his childhood in England. He and his wife, Kristiana, have three children.
On Expedition 45 to the International Space Station, he was led by fellow U.S. astronaut Scott Kelly.