Overview
The ISS expedition system provides continuous crewed presence aboard the station. Each expedition is numbered sequentially and typically lasts around six months. Since Expedition 1 arrived in November 2000, the ISS has been permanently crewed — the longest unbroken human presence in space, surpassing 25 years.
Early expeditions carried crews of just 2–3 people, transported exclusively by Russian Soyuz and the Space Shuttle. Following the Columbia disaster (2003) and Shuttle retirement (2011), crew size shrank temporarily before expanding again. The arrival of SpaceX Crew Dragon in 2020 restored US crew launch capability and enabled the station to support larger crews of 6–7 on a regular basis.
Early Expeditions (2000–2006)
The first era of ISS expeditions saw small crews of 2–3 people, transported by Soyuz and the Space Shuttle. Assembly was in full swing, with major modules arriving on nearly every Shuttle visit.
| Expedition | Dates | Commander | Crew Size | Transport | Notable |
|---|---|---|---|---|---|
| 1 | Oct 2000 – Mar 2001 | Bill Shepherd (NASA) | 3 | Soyuz TM-31 | First permanent crew; established continuous habitation |
| 2 | Mar – Aug 2001 | Yury Usachov (RSA) | 3 | STS-102 / Soyuz TM-32 | First EVA from the Quest airlock |
| 3 | Aug – Dec 2001 | Frank Culbertson (NASA) | 3 | STS-105 / Soyuz TM-33 | Witnessed September 11 attacks from orbit |
| 4 | Dec 2001 – Jun 2002 | Yuri Onufriyenko (RSA) | 3 | Soyuz TM-33 | First US science officer role |
| 5 | Jun – Dec 2002 | Valery Korzun (RSA) | 3 | STS-111 | Peggy Whitson's first mission |
| 6 | Nov 2002 – May 2003 | Ken Bowersox (NASA) | 3 | STS-113 | Crew returned on Soyuz after Columbia disaster grounded Shuttle |
| 7–12 | Apr 2003 – Oct 2005 | Various | 2 | Soyuz only | Reduced to 2-person "caretaker" crews during Shuttle stand-down |
| 13 | Mar – Sep 2006 | Pavel Vinogradov (RSA) | 2–3 | Soyuz TMA-8 | First Brazilian astronaut (Marcos Pontes) visited station |
Assembly & Growth Era (2006–2011)
With the Shuttle returning to flight, ISS assembly accelerated. New modules arrived (Columbus, Kibo, Tranquility, Cupola) and the crew expanded to six with Expedition 20 in 2009.
| Expedition | Dates | Commander | Crew Size | Notable |
|---|---|---|---|---|
| 14–19 | Sep 2006 – May 2009 | Various | 3 | Columbus (Exp 16), Kibo lab (Exp 17), Kibo exposed facility (Exp 19) installed |
| 20 | May – Oct 2009 | Gennady Padalka (RSA) | 6 | First six-person crew — expanded ISS capability |
| 21–28 | Oct 2009 – Nov 2011 | Various | 6 | Tranquility & Cupola (Exp 22), Leonardo PMM (Exp 26), AMS-02 delivered (Exp 28) |
Post-Shuttle Era (2011–2020)
After the final Shuttle flight (STS-135, July 2011), all crew transport relied on Russian Soyuz. This era saw expeditions lengthen, the One-Year Mission, and growing international participation.
| Expedition | Dates | Commander | Crew Size | Notable |
|---|---|---|---|---|
| 29–42 | Sep 2011 – Sep 2015 | Various | 6 | Soyuz-only transport era; Bigelow BEAM expandable module arrived (Exp 47); growing ESA/JAXA crew participation |
| 43/44 | Mar 2015 – Mar 2016 | Scott Kelly / Gennady Padalka | 6 | One-Year Mission — Scott Kelly and Mikhail Kornienko spent 340 days aboard for long-duration health research |
| 45–62 | Sep 2015 – Apr 2020 | Various | 3–6 | Continued science operations; Christina Koch set women's single-flight record (328 days, Exp 59–61); first all-female EVA (Exp 61) |
Commercial Crew Era (2020–Present)
SpaceX Crew Dragon Demo-2 (May 2020) restored US crew launch capability. From Expedition 63 onwards, crews have launched on both Soyuz and Crew Dragon, enabling larger rotations and commercial crew visits (Axiom missions).
| Expedition | Dates | Commander | Crew Size | Notable |
|---|---|---|---|---|
| 63 | Apr – Oct 2020 | Chris Cassidy (NASA) | 3 | Crew Dragon Demo-2 (Hurley & Behnken) visited during this expedition — first commercial crew to ISS |
| 64 | Oct 2020 – Apr 2021 | Shannon Walker (NASA) | 7 | First operational Crew Dragon rotation (Crew-1); ISS population expanded to 7 |
| 65–66 | Apr 2021 – Mar 2022 | Akihiko Hoshide (JAXA) / Anton Shkaplerov (RSA) | 7 | Nauka module arrived (Exp 65); Prichal docked (Exp 66) |
| 67 | Mar – Oct 2022 | Oleg Artemyev (RSA) | 7 | Axiom-1 first commercial crew visit (Apr 2022) |
| 68–69 | Oct 2022 – Sep 2023 | Sergey Prokopyev (RSA) / Andreas Mogensen (ESA) | 7 | ESA's Mogensen became first Danish ISS commander (Exp 70); Crew-6 and Crew-7 rotations |
| 70–71 | Sep 2023 – Sep 2024 | Andreas Mogensen (ESA) / Matthew Dominick (NASA) | 7 | Starliner CFT arrived (Jun 2024); Wilmore & Williams remained aboard after Starliner returned uncrewed |
| 72 | Sep 2024 – Mar 2025 | Suni Williams (NASA) | 7 | Williams took command after extended stay; Crew-9 arrived with only 2 astronauts to make room for Starliner returnees |
| 73 | Mar 2025 – present | TBD | 7 | Current expedition — Crew-10 rotation |
How ISS Expeditions Work
Numbering: Expeditions are numbered sequentially. When half the crew is replaced (typically every three months), the expedition number increments. A full crew rotation cycle spans two expedition numbers — for example, astronauts arriving during Expedition 72 may remain through Expedition 73.
Command: The ISS commander rotates between NASA and Roscosmos (and occasionally ESA or JAXA) astronauts. The commander is responsible for crew safety, station operations and coordinating activities between agencies.
Transport: As of 2026, crew transport is handled by SpaceX Crew Dragon and Roscosmos Soyuz. Crew Dragon launches from Kennedy Space Center (LC-39A), while Soyuz launches from the Baikonur Cosmodrome in Kazakhstan. Boeing Starliner's future crew rotation role remains uncertain following the CFT thruster issues in 2024.
Science: Each expedition conducts hundreds of experiments across disciplines including human physiology, biology, fluid physics, materials science, Earth observation and technology demonstrations. Research is coordinated through NASA's ISS National Laboratory, as well as ESA, JAXA and other partner programmes.