1. Construction background and participating countries
The International Space Station (ISS) began assembly in 1998 with the launch of its first module, Russia's Zarya, and was built in stages through 2011. It is a leading international space cooperation project involving the United States, Russia, Europe, Japan, and Canada.
2. The cooperative structure among partner agencies
Five space agencies β NASA (US), Roscosmos (Russia), ESA (Europe), JAXA (Japan), and CSA (Canada) β jointly operate the ISS, sharing modules, operating costs, and crew seats among themselves.
3. Orbital altitude and period
The ISS orbits in low Earth orbit at an altitude of about 400 km, traveling at roughly 28,000 km/h, and takes about 90 minutes to complete one orbit of Earth. Thanks to this, it experiences about 16 sunrises and sunsets a day.
4. Microgravity environment experiments
The ISS provides a microgravity environment close to weightlessness, functioning as a space laboratory for conducting biological, physical, and materials-science experiments that can't be done on the ground.
5. Representative scientific experiments
Ongoing experiments include growing plants in space, studying the long-term effects of weightlessness on human muscle and bone density, and growing protein crystals used in developing new drugs.
6. Spacewalks (EVA) and maintenance
Astronauts regularly put on spacesuits and conduct extravehicular activity (EVA) to carry out maintenance work on the ISS, such as replacing solar panels and installing external equipment.
7. Resident crew and mission rotation
The ISS is normally home to 6 to 7 astronauts, who work in mission units called Expeditions, rotating out every few months.
8. Future retirement plans
NASA plans to operate the ISS until 2030 and then, in early 2031, use a deorbit vehicle (USDV) developed by SpaceX to bring it down for a controlled reentry into the Pacific Ocean; afterward, crewed activity in low Earth orbit is expected to continue with commercial private space stations.