How many people have been to the ISS in total
As of late 2025, more than 270 people from over 20 countries have visited the International Space Station. This total includes long-duration expedition crew, short-duration visiting crew, and private astronauts. The ISS is the only permanently inhabited space station in low Earth orbit, serving as a global laboratory for science, technology demonstration, and international cooperation. Below we break down who has flown, how we count visitors, and how the number changes with each mission.
What counts as a person who has been to the ISS
Expedition crew versus visiting crew
Expedition crew are the long-duration residents who live aboard the ISS for several months, typically rotating in increments of about six months. Visiting crew include short-stay travelers, such as those ferrying cargo or conducting brief science programs. Both categories are counted as people who have been to the ISS. Mission classifications, however, do not include personnel who never left the spacecraft or who only completed suborbital hops without entering the station.
- Expedition crew: Long-duration residents, usually six months per expedition.
- Visiting crew: Short-duration travelers, including crew swaps and private astronauts.
- Exclusions: Personnel who remained solely on launch and return vehicles.
Verified total count and notable milestones
The ISS program began continuous crew occupation in November 2000 with Expedition 1. Since then, the station has hosted a continually growing roster of visitors from an expanding set of nations. The following table summarizes key totals as of late 2025, drawing on official NASA, Roscosmos, and international partner sources.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Total people to date (approximate) | Over 270 individuals | Program summaries and mission records |
| Number of countries represented | More than 20 | International partner reports |
| First expedition (Expedition 1) | October 2000–March 2001 (Expedition 1) | NASA ISS Expedition logs |
| Continuous occupation start | November 2000 | Program history records |
| Typical expedition duration | About six months | ISS crew schedules |
How incrementally the number grows
The ISS visitor count increases with each crew rotation, new research visits, and occasional private astronaut flights. Each increment corresponds to a specific mission and its manifest of crew members. Some years bring more visitors due to multiple crew swaps or the addition of commercial destinations, while other periods see more standard expedition rotations. Tracking relies on agency press kits, official crew biographies, and postmission summaries published by space agencies.
Where the data comes from and how it is confirmed
Numbers in this explainer are drawn from publicly available NASA ISS mission summaries, Roscosmos crew manifests, and statements from international partners such as ESA, JAXA, and CSA. Cross-agency tables and independent summaries are used to triangulate the total count. Private astronaut missions that dock with the ISS are also included when confirmed by program authorities and operators.
Limitations and what is not included
- Personnel who never entered the ISS or only remained in transit vehicles.
- Individuals on non docking spacecraft that did not reach ISS.
- Contingency or backup crew members who did not fly.
Status as of 2025 and how to stay updated
The ISS visitor tally remains approximate because missions are planned and adjusted over time. New expeditions, commercial visits, and international flights can update the total. For the most current precise count, consult NASA ISS mission pages and partner agency updates, which reflect the latest rotations and arrivals.