How does an ISS expedition work?
The International Space Station has been continuously inhabited since November 2000. Each occupation period is numbered consecutively as an "Expedition" (Expedition 1, Expedition 2, and so on), typically lasting four to six months. The crew doesn't rotate all at once: handovers are staggered so experienced crew members remain aboard while new arrivals settle in, meaning the station is never left without people who know its systems in depth.
There are currently two ways to reach the station: the Russian Soyuz spacecraft, in service since 1967 and responsible for the vast majority of crewed spaceflights in history, and SpaceX's Crew Dragon capsule, which since 2020 restored the US ability to launch astronauts from its own soil after the Space Shuttle was retired in 2011. Each vehicle typically carries three to four crew members, plus supplies and science experiments in its cargo section.
The crew combines career astronauts from the project's five partner agencies (NASA, Roscosmos, ESA, JAXA and CSA) with, occasionally, participants from commercial missions or other countries' programs through bilateral agreements. Onboard, work is split between microgravity science experiments (biology, fluid physics, medicine), station system maintenance, spacewalks for external tasks, and, increasingly, outreach and communication with schools and the public.
Who's who on board
Every expedition has a commander, who coordinates the daily work and takes the decisions in an emergency. Command is handed over in a short ceremony a few days before the outgoing commander returns to Earth, and it can go to an astronaut from any of the partner agencies. The rest of the crew are flight engineers: that's the name of the post, not a qualification, and it's held alike by pilots, doctors, scientists and engineers.
Seats are shared out according to what each partner contributes. On the US segment, NASA has a little over three quarters of the crew time, Japan around 13%, Europe a little over 8% and Canada a little over 2%. Roscosmos runs its own segment, usually with two or three cosmonauts. Since 2022, NASA and Roscosmos have also swapped seats: a cosmonaut usually flies on each Crew Dragon and a NASA astronaut on each Soyuz, so there's always someone from each side on board if one of the spacecraft has to stay on the ground.
How to read each card
The color of the circle on each card shows the crew member's agency, and the buttons above the list let you filter by agency. Under the name you'll see three figures: space flights, spacewalks (EVAs, extravehicular activities) and total days in space across all their missions, according to the public records we use. Members of the current expedition also have their own profile with a biography, which opens when you tap their card.
Why the list changes
Crews rotate roughly every six months, arriving on Soyuz and Crew Dragon. During a handover, or when a private mission visits the station for a couple of weeks, there can be ten or eleven people on board for a few days. The list updates itself, so it always shows who's up there right now.