People have lived aboard the ISS without a break since November 2000
Since the first long-stay crew arrived on 2 November 2000, there has not been a single moment without humans aboard the International Space Station. It is roughly the size of a football pitch, holds as much pressurised space as a jumbo jet, and circles Earth about every 93 minutes.
The station is the product of rivals turned partners. It merged two stations that were never built on their own, America's Space Station Freedom and the Soviet Union's Mir-2, and is run by five agencies: NASA, Roscosmos, the European Space Agency, Japan's JAXA and Canada's CSA. The first module flew in 1998, delivered along with later pieces by Proton, Soyuz and Space Shuttle rockets. It is split into a Russian segment and a US segment, joined by a long truss carrying solar panels and radiators. Altogether it counts 43 modules and elements, 16 of them major pressurised sections, and by August 2025 it had received 290 visitors from 26 countries.
It flies about 400 kilometres up, beneath the Van Allen radiation belts and most orbital debris, at 7.67 kilometres per second, which works out to 15.5 laps of the planet each day. Crews now arrive on Soyuz and Crew Dragon, while cargo comes on ships such as Progress, Cygnus and Cargo Dragon.
The research menu is broad: astronomy, materials science, fluid physics, combustion, plant growth and, above all, the human body. Long stays reveal muscle wasting, bone loss and fluid shifts, and a 2006 analysis warned that astronauts arriving on Mars after a six-month cruise might risk fractures. Since there is usually no doctor aboard, astronauts perform ultrasound scans guided by specialists on the ground, a method that may help rural medicine on Earth. The Alpha Magnetic Spectrometer, which NASA ranks alongside Hubble in importance, reported in 2013 an unexplained excess of high-energy positrons that might hint at dark matter, and in 2020 researchers found the hardy bacterium Deinococcus radiodurans had survived three years exposed outside the station.
The station is expected to keep working until the end of 2030. Parts are then meant to be reused for a commercial Axiom station and a new Russian outpost, and the rest steered to destruction by a US deorbit vehicle, though as of 2026 a proposal to park it in a higher, more stable orbit instead had won support in Congress.
Source: International Space Station
