The space shuttle Endeavor completed its 130th mission Sunday, landing in Cape Canaveral after a two-week trip to work on the International Space Station. The $100 billion space station, a project of 16 nations, has been under construction 220 miles from earth for 12 years. Endeavor carried the station’s final connecting hub, a second living quarters for the station’s crew. The module added a toilet, water-recycling system, oxygen generator, air scrubber and exercise equipment, but perhaps most spectacularly, an observation deck with seven windows that astronauts say provides an amazing view. This trip marks one of the last five for Endeavor before the U.S. retires its three shuttles later this year.