The 108-meter backbone of the International Space Station

Space · Published 21 October 2026 · Updated 21 October 2026 Swipe more like this →

In short: The International Space Station relies on a massive skeletal framework to survive the vacuum of space. Known as the Integrated Truss Structure, this backbone serves as the primary mounting point for power, cooling, and heavy payloads. It wasn't built all at once; it was assembled piece by piece over nearly a decade.

The Integrated Truss Structure (ITS) serves as the primary backbone of the International Space Station. It provides the essential mounting points for the station's most critical external systems, including the large solar arrays that generate power, the thermal control radiators that dissipate heat, and various external payloads. Beyond these primary functions, the truss acts as a utility corridor, housing electrical and cooling lines as well as the rails for the Mobile Transporter.

The construction of the ITS was a multi-year logistical feat involving numerous Space Shuttle missions. The assembly began on October 14, 2000, with the installation of the Z1 truss segment. This was followed by a staggered rollout of various segments over the next nine years. The structure is organized into three main orientations: the Starboard "S" truss (6 segments), the Port "P" truss (5 segments), and the Zenith "Z" truss (1 segment).

In total, the structure consists of 11 segments plus the Z1 component. When fully extended with its solar arrays, the ITS reaches a total length of 108.5 meters (356 feet). The assembly was highly specific; for example, the solar arrays were delivered in batches with specific truss pairs like S3/S4 and P3/P4, while radiators were distributed across S1, S3, S6, and P1, P3, and P4. This modular approach allowed for a complex, distributed system to be integrated into a single, rigid framework in the orbital environment.

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