Unity, also known as Node 1, is the first U.S.-built component of the International Space Station (ISS). This cylindrical module, constructed of aluminium by Boeing for NASA, serves as the critical link between the orbiting laboratory's Russian Orbital Segment and US Orbital Segment.
Unity was launched on December 4, 1998, aboard the Space Shuttle Endeavour on STS-88. Two days later it was berthed to the previously launched Zarya module, marking the first connection between ISS components. Its six Common Berthing Mechanism (CBM) locations (forward, aft, port, starboard, zenith, and nadir) facilitate connections to other modules. At launch, two CBM locations were fitted with Pressurized Mating Adapters (PMA), one of which enabled the mating with Zarya.
Measuring 4.57 metres (15.0 ft) in diameter and 5.47 metres (17.9 ft) in length, Unity was built at NASA's Marshall Space Flight Center. It is the first of three connecting modules, joined by Harmony and Tranquility.
Unity (with its two attached PMAs) was carried into orbit as the primary cargo of the Space Shuttle Endeavour (OV 105) on STS-88, the first Space Shuttle mission dedicated to assembly of the station. On December 6, 1998, the STS-88 crew mated the docking port of the PMA on the aft berthing port of Unity with the forward hatch of the already orbiting Zarya module. (Zarya was a mixed Russian-U.S. funded and Russian-built component launched a few days before aboard a Russian Proton launch vehicle from Baikonur, Kazakhstan.)
Connecting modules and visiting vehicles
Unity has two axial and four radial Common Berthing Mechanism (CBM) ports. In addition to connecting to the Zarya module, Unity connects to the U.S. Destiny Laboratory Module (added on STS-98), the Z1 truss (an early exterior framework for the station added on STS-92), the PMA-3 (also added on STS-92), and the Quest Joint Airlock (added on STS-104). During STS-120 the Harmony module was temporarily berthed to the port-side hatch of Unity. Tranquility, with its multi-windowed cupola, was attached to Unity's port side during the STS-130 mission, and Leonardo was added to the nadir hatch during STS-133.
In addition, the Leonardo and Raffaello Multi-Purpose Logistics Modules were each berthed to Unity on multiple missions.
PMA-2, launch–2001 (relocated to Destiny forward in 2001 and again to Harmony forward in 2007)
STS-96, May 27, 1999, 10:49–June 6, 1999, 02:02
STS-101, May 20, 2000, 04:30–May 26, 2000, 23:03
STS-106, September 8, 2000, 12:45–September 19, 2000, 07:56
STS-92, October 11, 2000, 23:17–October 24, 2000, 20:59
Zarya (via PMA-1), December 6, 1998–present
PMA-3, March 2001–August 30, 2007
Harmony, October 26–November 12, 2007
PMA-3, August 7, 2009–January 25, 2010
Tranquility, February 12, 2010–present
Z1 truss, October 14, 2000–present