67% Volume Jump: 2007 Harmony Delivery Reshaped Station Layout

For decades, the International Space Station grew in isolated increments, with major interior additions spaced years apart. On October 23, 2007, that pattern shifted when the space shuttle Discovery lifted off on mission STS-120, carrying the Harmony module to the orbiting outpost.

The delivery expanded the station's internal volume by approximately 67%, a jump that changed the complex's scale from the size of a three-bedroom house to that of a five-bedroom house. Harmony measures 14 feet wide and 24 feet long, a footprint roughly equivalent to a minibus. This increase in living and working space was the largest single interior expansion the station had seen since the launch of the Unity node.

Harmony serves as a central utility hub, originally designated as Node 2. It was built for NASA by the Italy-based firm Thales Alenia Space. The module features five common berthing mechanisms, which act as connection points for other sections of the station. Before this delivery, the most recent new room added to the station was Russia's Pirs docking module, which arrived in 2001 and has since been discarded.

Upon arrival, astronauts initially attached Harmony temporarily to the Unity node. After the shuttle departed, the crew used the station's robotic arm to move the shuttle docking port out of the way at the Destiny laboratory. This maneuver cleared the path for Harmony to be berthed at its permanent location beside Destiny. From this forward position, Harmony became the critical link for the European Space Agency's Columbus module on the starboard side and Japan's Kibo laboratory on the port side.

Inside the module, eight payload racks manage the station's operations. Four of these racks house avionics, while the remaining four are used for stowage or crew quarters. NASA's American astronauts use the module for their sleeping quarters. The name Harmony was selected through a public naming contest run by NASA. Some of its berthing ports have since been used by visiting cargo ships, and a docking port on its roof allows other vehicles to park there.