International Space Station Modules

A space station is a crewed spacecraft that remains in orbit for extended periods and supports long duration habitation, most often assembled from separate pressurized and unpressurized modules launched individually and joined together in orbit rather than built and launched as a single vehicle. A module in this modular design serves one or more dedicated functions, such as crew living quarters, an observation post, a scientific laboratory rack, or a station keeping propulsion element, and is typically berthed or docked to an existing station after being carried to orbit inside a launch vehicle's payload fairing or cargo bay. The International Space Station's own module inventory includes both elements that reached orbit and were permanently attached, and elements that were designed, and in some cases partially built, for the station but were cancelled before launch and never flown.