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.
Richard Mastracchio Richard Alan "Rick" Mastracchio (born February 11, 1960) is an American engineer and former NASA astronaut. He has flown on three NASA Space Shuttle missions as a mission specialist in addition to serving as a Flight Engineer on the Soyuz TMA-11M (Expedition 38/Expedition 39) long duration mission aboard the International Space Station. He is currently the Senior Director of Operations for Commercial Resupply Services at Orbital ATK.