Who flew on more Space Shuttle missions, meteorologist Piers Sellers or chemical engineer Lodewijk van den Berg?
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.
Rex J. Walheim Rex Joseph Walheim (born October 10, 1962) is a United States Air Force officer, engineer and a NASA astronaut. He has flown three space shuttle missions, STS-110, STS-122, and STS-135. Rex has logged over 566 hours in space, including 36 hours and 23 minutes of spacewalk (EVA) time. He was assigned as mission specialist and flight engineer on STS-135, the final space shuttle mission.