The International Space Station has been orbiting Earth for 25 years.
It is constructed from Russian and US segments, with additional modules from the European and Japanese space agencies.
The station is approximately the length of an American football field, travels at 17,000 to 17,500 mph, and orbits Earth roughly every 90 minutes.
Astronauts on board conduct experiments and serve as test subjects for measurements before, during, and after space flights to study human survival on long-duration missions, with most crews serving about six months.