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 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 in diameter and 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.

Launch and initial berthing 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.

Forward 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 Destiny, 2001–presentAft PMA-1, launch–present Zarya (via PMA-1), December 6, 1998–presentPort 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–presentStarboard Quest, July 15, 2001–presentZenith Z1 truss, October 14, 2000–presentNadir PMA-3, October 16, 2000–March 2001 STS-97, December 2–9, 2000 STS-98, February 9–16, 2001 PMA-3, August 30, 2007–August 7, 2009 Leonardo, March 1–May 27, 2015 CRS OA-4, December 9, 2015–February 19, 2016 CRS OA-6, March 26–June 14, 2016 CRS OA-5, October 17–November 27, 2016 CRS OA-7, April 22–June 4, 2017 CRS OA-8E, November 14–December 5, 2017 CRS OA-9E, May 24–July 15, 2018 CRS NG-10, November 19, 2018–February 8, 2019 CRS NG-11, April 19–August 6, 2019 CRS NG-12, November 4, 2019–January 31, 2020 CRS NG-13, February 18–May 11, 2020 CRS NG-14, October 5, 2020–January 26, 2021 CRS NG-15, February 20–June 29, 2021 CRS NG-16, August 12–December 15, 2021 CRS NG-17, February 21–June 28, 2022 CRS NG-18, November 9, 2022–April 21, 2023 CRS NG-19, August 4–December 22, 2023 CRS NG-20, February 1–July 12, 2024 CRS NG-21, August 6, 2024–March 28, 2025 CRS NG-23, September 18, 2025–March 14, 2026

Details

Essential space station resources such as fluids, environmental control and life support systems, electrical and data systems are routed through Unity to supply work and living areas of the station. More than 50,000 mechanical items, 216 lines to carry fluids and gases, and 121 internal and external electrical cables using six miles of wire were installed in the Unity node. The primary structure of Unity is constructed of aluminium.

During the space station construction, a crew member placed two speed limit signs on the hatch (leading into the FGB) in 2003, noting the orbital velocity in mph and km/h.

Prior to its launch aboard Endeavour, conical Pressurized Mating Adapters (PMAs) were attached to the aft and forward berthing mechanisms of Unity. Unity and the two mating adapters together weighed about . The adapters allow the docking systems used by the Space Shuttle and by Russian modules to attach to the node's hatches and berthing mechanisms. PMA-1 now permanently attaches Unity to Zarya, while PMA-2 provided a Shuttle docking port. Attached to the exterior of PMA-1 are computers, or multiplexer-demultiplexers (MDMs), which provided early command and control of Unity. Unity also is outfitted with an early communications system that allows data, voice and low data rate video with Mission Control Houston, to supplement Russian communications systems during the early station assembly activities. PMA-3 was attached to Unitys nadir berthing mechanism by the crew of STS-92.

Other nodes

The two remaining station connecting modules, or nodes, were manufactured in Italy by Alenia Aerospazio, as part of an agreement between NASA and the European Space Agency (ESA). Harmony (also known as Node 2) and Tranquility (also known as Node 3) are slightly longer than Unity, measuring almost long in total. In addition to their six berthing ports, each can hold eight International Standard Payload Racks (ISPRs). Unity, in comparison, holds just four ISPRs. ESA built Nodes 2 and 3 as partial payment for the launch aboard the Shuttle of the Columbus'' laboratory module, and other ESA equipment.

References

External links NASA Facts: Unity Connecting Module: cornerstone for a Home in Orbit NASA, January 1999 Expedition 15 - Tour of the Unity Node filmed in July 2007 by Clayton Anderson