Question: Has Piers Sellers or Hans Schlegel been on more Space Shuttle Missions?
Context: Integrated Cargo Carrier (ICC) was a project, started in 1997 by the companies Spacehab and Astrium North America, Inc., to develop a family of flight proven and certified cross-the-bay cargo carriers designed to fly inside the Space Shuttle cargo bay, installed either horizontally or vertically, and able to carry up to 8000 lbs.  of unpressurized cargo into orbit.  Astrium North America, Inc. currently owns the ICC fleet of carriers.  The ICC carriers flew on 12 Space Shuttle missions between 1999 and 2010 under NASA's Cargo Mission Contract contributing to the construction, supply and maintenance of the International Space Station (ISS), transporting more than 50 unpressurized cargo elements (over 34,000 pounds) into orbit and providing for permanent attachment of two External Stowage Platforms (ESP-2 and ESP-3) to the ISS.  Astrium North America's former Cape Canaveral integration facility, which was located at Astrotech's processing facility (formerly SPACEHAB Payload Processing Facility (SPPF)) provided for the physical integration of cargoes to the ICC and subsequent transport to Kennedy Space Center for orbiter installation.  Due to its modular design and versatility, options to adapt the ICC design to new commercial orbital space transportation vehicles exist. Claude Nicollier (born 2 September 1944 in Vevey, Switzerland) is the first astronaut from Switzerland.  He has flown on four Space Shuttle missions.  His first spaceflight (STS-46) was in 1992, and his final spaceflight (STS-103) was in 1999.  He took part in two servicing missions to the Hubble Space Telescope (called STS-61 and STS-103).  During his final spaceflight he participated in a spacewalk, becoming the first European Space Agency astronaut to do so during a Space Shuttle mission (previous ESA astronauts conducted spacewalks aboard "Mir", see List of spacewalks and moonwalks 1965–1999).  In 2000 he was assigned to the Astronaut Office Extravehicular Activity Branch, while maintaining a position as Lead ESA Astronaut in Houston.  Nicollier retired from ESA in April 2007. The NASA recovery ships are two ships, the  and the  , that were tasked with retrieving spent Solid Rocket Boosters (SRBs) following the launch of Space Shuttle missions.  Although owned by NASA, the ships were operated by Space Flight Operations contractor United Space Alliance.  Following the end of the Space Shuttle program, and therefore booster recovery, NASA transferred both vessels to the Department of Transportation. Charles Donald "Sam" Gemar (born on the 4th August, 1955) is an American former astronaut with NASA and a lieutenant colonel in the United States Army.  Gemar has flown on three Space Shuttle missions (STS-38, STS-48 and STS-62).  Gemar has completed 385 orbits of the Earth and over 581 hours in space.  He has also served in different positions in NASA, including as a CAPCOM for Shuttle missions.  Gemar was the first astronaut to be born in the state of South Dakota. 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. Hans Wilhelm Schlegel (Überlingen, 3 August 1951) is a German physicist, an ESA astronaut, and a veteran of two NASA Space Shuttle missions. Colonel Benjamin Alvin Drew (born November 5, 1962) is a United States Air Force officer and a NASA astronaut.  He has been on two spaceflights; the first was the Space Shuttle mission STS-118 to the International Space Station, in August 2007.  Drew's second spaceflight took place in March 2011 on STS-133, another mission to the International Space Station.  STS-133 was Space Shuttle "Discovery"'s final mission.  Drew took part in two spacewalks while docked to the station.  Drew was the final African-American to fly on board a Space Shuttle, as the final two Space Shuttle missions, STS-134 and STS-135, had no African-American crew members. Dafydd Rhys "Dave" Williams (born May 16, 1954) is a Canadian physician, public speaker and a retired CSA astronaut.  Williams was a mission specialist on two space shuttle missions.  His first spaceflight, STS-90 in 1998, was a 16-day mission aboard Space Shuttle "Columbia" dedicated to neuroscience research.  His second flight, STS-118 in August 2007, was flown by Space Shuttle "Endeavour" to the International Space Station.  During that mission he performed three spacewalks, becoming the third Canadian to perform a spacewalk and setting a Canadian record for total number of spacewalks.  These spacewalks combined for a total duration of 17 hours and 47 minutes. Chiaki Mukai (向井 千秋 , Mukai Chiaki ) is a Japanese doctor, and JAXA astronaut.  She was the first Japanese woman in space, and was the first Japanese citizen to have two spaceflights. Both were Space Shuttle missions; her first was STS-65 aboard Space Shuttle "Columbia" in July 1994, which was a Spacelab mission.  Her second spaceflight was STS-95 aboard Space Shuttle "Discovery" in 1998.  In total she has spent 23 days in space. Space Shuttle missions designated STS-3xx (officially called Launch On Need (LON) missions) were rescue missions which would have been mounted to rescue the crew of a Space Shuttle if their vehicle was damaged and deemed unable to make a successful reentry.  Such a mission would have been flown if Mission Control determined that the heat shielding tiles and reinforced carbon-carbon panels of a currently flying orbiter were damaged beyond the repair capabilities of the available on-orbit repair methods.  These missions were also referred to as Launch on Demand (LOD) and Contingency Shuttle Crew Support.  The program was initiated following loss of Space Shuttle "Columbia" in 2003.  No mission of this type was launched during the Space Shuttle program.
Answer: Piers John Sellers OBE