This year, the International Space Station celebrated 20 years of having a continuous human presence on it.
There have been 242 individuals from 19 countries who have made trips to the station, including the latest four who launched from Cape Canaveral on Sunday: Michael Hopkins, Victor Glover, Shannon Walker and Soichi Noguchi.
But what exactly is the International Space Station and what does it do?
Here’s a guide to key questions and facts about the ISS.
What purpose does the ISS serve?
Created in 1998 when government officials from 15 nations signed an agreement for its design, development and utilization, the main purpose of the ISS is to serve as a research laboratory for microgravity and space environment.
Experiments are conducted by crew members in fields such as biology, physics, astronomy and meteorology.