International Space Station (ISS): What It Is
The International Space Station (ISS) is a permanently crewed research laboratory in low Earth orbit built and operated through an international partnership led by NASA (United States), Roscosmos (Russia), ESA (Europe), JAXA (Japan), and CSA (Canada). NASA states the ISS has been continuously occupied since November 2000.
The station provides a microgravity environment used for research across human health, biology, physics, materials science, and technology demonstrations that support future exploration. NASA notes the ISS orbits Earth about 16 times per day, with an orbital period of roughly 90 minutes.
ISS Fast Facts
- First ISS element launched: Nov. 20, 1998 (Zarya module)
- Continuously occupied: Since Nov. 2000
- Mass: 925,335 lb (419,725 kg)
- End-to-end length: 356 ft (109 m)
- Pressurized volume: 35,491 ft³ (1,005 m³)
- Power generation: ~75 to 90 kW from 8 solar arrays
ISS Statistics and Facts (NASA)
| Pressurized module length | 218 ft (67 m) |
| Truss length | 310 ft (94 m) |
| Solar array span (longitudinal arrays) | 239 ft (73 m) |
| Habitable volume (not including visiting vehicles) | 13,696 ft³ (388 m³) |
| Pressurized volume | 35,491 ft³ (1,005 m³) |
| Power generation | 8 solar arrays provide ~75–90 kW |
| Lines of software code (approx.) | ~1.5 million |
NASA: Space Station Facts and Figures
ISS Spacewalks
Total spacewalks at the ISS: NASA’s Station Overview reports 277 spacewalks conducted at the International Space Station since December 1998. (Because this number changes, use the NASA log below as the evergreen reference.)
ISS Visitors (People and Countries)
Total visitors to the ISS: NASA reports 292 individuals representing 26 countries have visited the International Space Station.
NASA: Visitors to the Station by Country
ISS Records (NASA Astronauts)
- Longest single NASA spaceflight: Frank Rubio — 371 days
- Most cumulative days in space (NASA record): Peggy Whitson — 675 days
NASA: Space Station Astronaut Record Holders
FAQ
How long has the ISS been continuously occupied?
NASA states the station has been continuously occupied since November 2000.
How many times does the ISS orbit Earth each day?
NASA notes the ISS orbits Earth about 16 times per day (roughly one orbit every 90 minutes).
How big is the ISS?
NASA lists the ISS as 356 feet (109 meters) end-to-end, with a pressurized volume of 35,491 cubic feet (1,005 cubic meters).