Complex sentence: In his 11 years with NASA, he flew on four space shuttle missions, logging a total of 53 days in space, including three spacewalks to install the centerpiece science module of the International Space Station (ISS).
Split into simpler sentences: In his 11 years with NASA he flew on four space shuttle missions, logging a total of 53 days in space. His flight time included three spacewalks to install the centerpiece science module of the International Space Station (ISS).