The largest space station is the International Space Station (ISS), the first components of which were launched on 20 November 1998. As of 22 December 2021, following the addition of the Russian Multipurpose Laboratory Module Nauka and the Prichal docking node, the ISS has a total mass of 418,190 kg (921,951 lb) – rising to 459,025 kg (1,011,976 lb) including docked visiting spacecraft – and a pressurized volume of around 950 m^3 (33,548 cu ft) – not including visiting spacecraft.
In July 2021,International Space Station received its first major addition in more than a decade with the arrival of the Russian Nauka module. This orbital laboratory adds another 70 cubic metres to the pressurized internal volume of the ISS, including an additional bunk and toilet as well as dedicated laboratory equipment such as freezers, furnaces and computer workstations. It was extended further with the addition of the Prichal docking node on 26 November 2021.
The first resident crew of theISS arrived on 2 November 2000, and the station has been continually occupied since – making it the longest serving human outpost in space. During that time, the ISS has hosted 244 astronauts, cosmonauts and space tourists from 19 different nations.
TheISS is designed to provide a platform for scientific research, with multiple laboratory modules and external experiment racks. The crew manage a wide range of instruments and experiments in the unique microgravity environment, while also serving as living research subjects themselves – the focus of studies into the long-term effects of life in space.
The backbone of theISS is a 109-m-long aluminium-and-steel structural frame called the Integrated Truss Structure. This holds the unpressurized components of the station, including the solar arrays, cooling radiators, batteries and communications equipment. It also serves as an anchor point for the Canadarm2 robotic arm, which is used to inspect the station's exterior, grapple incoming spacecraft and transport spacewalking astronauts.
