The final piece of the puzzle: Discovery completes the ISS

Space · Published 18 October 2026 Swipe more like this →

In short: For 13 years, the International Space Station was a work in progress—a sprawling, unfinished skeleton in orbit. It took the final flight of NASA's most-flown shuttle, Discovery, to deliver the last American room, transforming the station into a complete multinational laboratory.

The assembly of the International Space Station (ISS) represents one of the most complex engineering feats in human history. Construction began in 1998 with the launch of the first Russian module, eventually evolving into a structure so large that its exterior spans the length of a football field. By the time the shuttle Discovery completed its final mission, STS-133, in March 2011, the project had become a collaborative effort involving 15 different countries and five space agencies, with a total construction cost reaching approximately $100 billion.

While the station was already functional, it lacked its final major American component. During STS-133, Discovery delivered the Permanent Multipurpose Module (PMM), a bus-sized storage room measuring 21 feet long and 15 feet wide. This addition provided the station's residents with more than 2,470 cubic feet of extra storage. Beyond this final room, the mission also involved the installation of the External Logistics Carrier, servicing various external structures, and berthing the Pressurized Mating Module, effectively finalizing the station's primary assembly.

The mission was bittersweet for NASA, marking the retirement of the space shuttle program after 30 years. Discovery, the most-flown shuttle in the fleet, completed its final landing at Kennedy Space Center on March 9, 2011, two days after undocking from the station. While only two shuttle missions remained in the program's schedule, neither was slated to deliver new U.S. modules, making STS-133 the definitive conclusion to the era of shuttle-led construction for the orbiting laboratory.

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