Carried aloft by the Space Shuttle Endeavour in December 1998, Unity, the first American component, will serve as a hub of sorts. Its two pressurized mating adapters will connect to Zarya and to the U.S. laboratory. Other station components that astronauts will eventually mate with Unity include the Z-1 truss exterior framework, the airlock, and the United States Habitation Module.
Members of the shuttle crew that helped attach Unity to Zarya pose before the Unity module at the Kennedy Space Center. (Hear mission specialist Jim Newman, far right in the photo, talk about building the space station.)