Has Piers Sellers or Hans Schlegel been on more Space Shuttle Missions?
Hans Schlegel Hans Wilhelm Schlegel (Überlingen, 3 August 1951) is a German physicist, an ESA astronaut, and a veteran of two NASA Space Shuttle missions.
John Young (astronaut) John Watts Young (born September 24, 1930) is an American former astronaut, naval officer and aviator, test pilot, and aeronautical engineer, who became the ninth person to walk on the Moon as Commander of the Apollo 16 mission in 1972.