ISS modules — a guided tour of the Station
The Station is not one thing but many — over a dozen pressurised modules bolted together in orbit, each with its own role. Here is a plain-language tour.
The International Space Station was not launched in one piece. It was assembled in orbit over more than a decade, module by module, each one carried up by a Shuttle, a Proton, or a Falcon and bolted on to what was already there. The result is not a spaceship — it is a street of laboratories and living quarters, arranged in a rough cross.
The backbone — the truss
Running through the middle is the Integrated Truss Structure, a hundred-metre-long spine that carries the solar arrays, radiators, and cooling systems. It is not a place you walk through — it is exposed scaffolding — but it is what holds the Station together and keeps it powered.
The Russian segment
The Station’s Russian side centres on Zvezda (Service Module), which provides life support, attitude control, and crew quarters. It was the first habitable module, and the Station’s living heart for its early years. Attached to it are:
- Zarya (FGB) — the very first module launched, in 1998. Originally provided propulsion and power; now mainly used for storage.
- Poisk and Rassvet — small docking modules where Soyuz and Progress spacecraft attach.
- Nauka — a long-delayed multipurpose laboratory that finally arrived in 2021, adding science capacity and a European robotic arm.
The American segment
The US side is organised around Unity (Node 1), Harmony (Node 2), and Tranquility (Node 3) — the three pressurised junctions that connect everything else.
Key modules:
- Destiny — NASA’s primary science laboratory, home to most US experiment racks.
- Columbus — ESA’s European laboratory, running physical-science and biology experiments.
- Kibo — JAXA’s Japanese laboratory, the Station’s largest pressurised module, with an external experiment platform and its own small airlock for deploying CubeSats.
- Cupola — the seven-windowed observation dome mounted under Tranquility, used for Earth observation and robotics control. It is the view you see on our live cameras.
How they connect
Modules attach through Common Berthing Mechanisms (CBMs) or Russian docking ports. Each connection carries power, data, and atmosphere. The result is that you can float from one end of the Station to the other — roughly the length of a football pitch — through a continuous pressurised corridor.
Still growing
Even now, new hardware arrives. The latest external additions include commercial airlocks for deploying payloads and new solar arrays (iROSA) that overlay the originals to restore power capacity as the old panels degrade. The Station will keep evolving until deorbit.
To understand how it all stays in orbit, read how we track the ISS. To meet the people living inside these modules right now, see the crew page.
Frequently asked
How many modules does the ISS have, and how was it assembled?
The Station is made of over a dozen pressurised modules bolted together in a rough cross, plus the long truss that carries the solar arrays. It was not launched in one piece but assembled in orbit over more than a decade, each module carried up separately by a Shuttle, Proton or Falcon.
What is the Cupola on the ISS?
The Cupola is a seven-windowed observation dome mounted under the Tranquility node, used for Earth observation and controlling the robotic arms. It is the Station's most photographed spot and the source of most of the spectacular low-orbit imagery you see online.
What are the main laboratory modules?
Destiny is NASA's primary science lab, Columbus is the European laboratory run by ESA, and Kibo is the Japanese laboratory built by JAXA, which is the Station's largest pressurised module and has its own airlock for deploying small satellites.
How do the Russian and US segments differ?
The Russian segment centres on Zvezda for life support and crew quarters alongside Zarya, Poisk, Rassvet and the Nauka laboratory. The US segment is organised around the Unity, Harmony and Tranquility nodes, which connect the Destiny, Columbus and Kibo laboratories.
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