Assembly of the International Space Station

The process of assembling the International Space Station (ISS) has been under way since the 1990s. Zarya, the first ISS module, was launched by a Proton rocket on 20 November 1998. The STS-88 Space Shuttle mission followed two weeks after Zarya was launched, bringing Unity, the first of three node modules, and connecting it to Zarya. This bare 2-module core of the ISS remained uncrewed for the next one and a half years, until in July 2000 the Russian module Zvezda was launched by a Proton rocket, allowing a maximum crew of three astronauts or cosmonauts to be on the ISS permanently.

The ISS has a pressurized volume of approximately 1,000 cubic metres (35,000 cu ft), a mass of approximately 410,000 kilograms (900,000 lb), approximately 100 kilowatts of power output, a truss 108.4 metres (356 ft) long, modules 74 metres (243 ft) long, and a crew of seven.^[1] Building the complete station required more than 40 assembly flights. As of 2020, 36 Space Shuttle flights delivered ISS elements. Other assembly flights consisted of modules lifted by the Falcon 9, Russian Proton rocket or, in the case of Pirs and Poisk, the Soyuz-U rocket.

Some of the larger modules include:

• Zarya (launched 20 November 1998)
• Unity Module (launched 4 December 1998, also known as Node 1)
• Zvezda (launched 12 July 2000)
• Destiny Laboratory Module (launched 7 February 2001)
• Harmony Module (launched 23 October 2007, also known as Node 2)
• Columbus orbital facility (launched 7 February 2008)
• Japanese Experiment Module, also known as Kibō (launched in multiple flights between 2008 and 2009)
• The truss, original and iROSA solar panels (unpressurized, truss and original panels launched in multiple flights between 2000 and 2009, iROSAs launched between 2021 and 2023, a final set of iROSAs are planned to be sent in 2025)
• Nauka (MLM-U) (launched 21 July 2021)