Has Piers Sellers or Hans Schlegel been on more Space Shuttle Missions?
Piers Sellers Piers John Sellers OBE (11 April 1955 – 23 December 2016) was a British-American meteorologist, NASA astronaut and Director of the Earth Science Division at NASA/GSFC. He was a veteran of three space shuttle missions.
Sergei Treshchov Sergei Yevgenyevich Treshchov (Сергей Евгеньевич Трещёв, born 18 August 1958) is a former cosmonaut of the RSC Energia. He spent 184 days in space as a flight engineer of the International Space Station long duration Expedition 5 crew. During the mission Treshchov also conducted a spacewalk.