Harmony, known prior as Node 2, is the "utility hub" of the International Space Station. The hub contains four racks that provide electrical power, bus electronic data, and act as a central connecting point for several other components via its six Common Berthing Mechanisms (CBMs). Harmony added to the station's living volume, an increase of almost 20 percent, from to The successful installation of Harmony means that from NASA's perspective, the station is now "U.S. Core Complete". Harmony was successfully launched into space aboard Space Shuttle flight STS-120 on 23 October 2007. After temporarily being attached to the port side of the Unity node, it was moved to its permanent location on the forward end of the Destiny laboratory on November 14 2007.
The unit formerly known as Node 2 was renamed Harmony in March 2007. The name was chosen from a competition involving more than 2,200 kindergarten through high school students from 32 states. The Node 2 Challenge required students to learn about the space station, build a scale model, and write an essay explaining their proposed name for the module, which will serve as a central hub for science labs.
Weighing approximately , Harmony is the second of three connectors between the major ISS modules. The design is based on the existing Multi-Purpose Logistics Module, as well as the European Space Agency's Columbus Module. Harmony is managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. Its deployment expanded the Space Station, allowing it to grow from the size of a three-bedroom house, to the space equivalent of a typical five-bedroom house, once the Japanese Kibō and European Columbus laboratories are attached. The Space Station robotic arm, Canadarm2, is able to operate from a powered grapple fixture on the exterior of Harmony. The node measures in length, and it has a diameter of .
On October 26, the station's Space Station Remote Manipulator System (SSRMS) removed Harmony from the shuttle cargo bay and temporarily mated it to the port side of Unity and, on October 27, the crew entered Harmony. After the Space Shuttle departed Harmony was relocated to the forward dock of the Destiny laboratory. It required three EVAs by the station crew to complete the installation.
The Expedition 16 crew moved the Pressurized Mating Adapter (PMA-2) on November 12 2007 from the Destiny Laboratory to the forward berth of Harmony. The combined PMA-2/Harmony unit was subsequently berthed to its final destination at the forward end of the Destiny Laboratory on November 14 2007.