Complex sentence: The three crew members it launched were relieved by Space Shuttle "Atlantis" during STS-71, when they were replaced by expedition EO-19, who returned to earth aboard Soyuz TM-21 on September 11,1995.
Split into simpler sentences: The three crew members it launched were relieved by Space Shuttle "Atlantis" during STS-71, when they were replaced by expedition EO-19. The crew returned to earth aboard Soyuz TM-21 on September 11,1995.