Discovery shuttle expanded ISS to five-bedroom scale in 2007

NASA astronauts delivered the Harmony module to the International Space Station on October 23, 2007, effectively doubling the volume of the orbiting outpost. The space shuttle Discovery carried the structure during the STS-120 mission, a move that transformed the station from a facility the size of a three-bedroom house into one comparable to a five-bedroom residence.

Harmony is a utility hub measuring 14 feet wide and 24 feet long. Built by Italy-based Thales Alenia Space for NASA, the module was originally designated Node 2. It contains five common berthing mechanisms that allow other modules to attach to the station. The name was selected through a public contest run by NASA.

Upon arrival, astronauts temporarily attached Harmony to the Unity node. After the shuttle departed, the crew used the station's robotic arm to move the shuttle docking port on the Destiny module. This maneuver cleared the forward port of the Destiny laboratory, allowing the crew to berth Harmony at its permanent location.

The installation marked a new phase in station growth by providing a central connection point for future modules. Before this delivery, the last new room added to the station was Russia's Pirs docking module in 2001. That structure was eventually discarded. Harmony now serves as the link for Europe's Columbus laboratory on the starboard side and Japan's Kibo laboratory on the port side.

Inside the module, eight payload racks occupy the interior space. Four racks house avionics equipment, while the remaining four are used for stowage or crew quarters. NASA's American astronauts use the module for sleeping quarters. A docking port on the roof also allows visiting vehicles to park at the station.

The STS-120 flight lasted approximately two weeks. Following the relocation, Harmony became the central hub for the US segment of the station. Its ports have hosted visiting cargo ships and continue to support the operational infrastructure of the orbiting complex.