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.
Gregory C. Johnson Gregory Carl "Ray J" Johnson (born July 30, 1954), (Capt, USNR, Ret.), is a former American naval officer and aviator, test pilot, aerospace engineer, and NASA astronaut. He spent his military career in both, the United States Navy and the Navy Reserve. He was the Pilot on Space Shuttle mission STS-125, the final Hubble Space Telescope servicing mission.