Complex sentence: He piloted STS-121 in 2006 and commanded STS-124 in 2008 and STS-134 in 2011, both his final mission and the final mission of space shuttle "Endeavour".
Split into simpler sentences: He piloted STS-121 in 2006 and commanded STS-124 in 2008. Kelly's final shuttle mission was as commander of STS-134, the final mission of space shuttle "Endeavour".