The International Space Station: 25 Years On

The International Space Station (ISS) is a large, permanently inhabited research laboratory that orbits Earth in low Earth orbit and serves as a hub for international human spaceflight and microgravity science. The ISS is a modular space station assembled from many interconnected components launched over multiple missions, forming the largest human‑made structure in space. It orbits Earth at an altitude of about 400 kilometers, circling the planet roughly once every 90 minutes and completing about 16 orbits per day. 
 
The station is a collaboration among five main space agencies: NASA (United States), Roscosmos (Russia), ESA (Europe), JAXA (Japan), and CSA (Canada). Up to about seven crew members from different countries typically live and work on board, making it a continuous international outpost in space since 2000. 
 
The ISS functions primarily as a microgravity laboratory where experiments in biology, physics, materials science, Earth observation, astronomy, and human physiology are carried out. It also serves as a testbed for space technologies and life‑support systems needed for future long‑duration missions to the Moon and Mars, helping researchers understand the effects of long‑term spaceflight on the human body.
 
The ISS is officially planned to operate only through about 2030, after which partner agencies intend to deorbit it in a controlled re‑entry over a remote stretch of ocean. NASA has already framed the 2020s as the station’s final decade of results, emphasizing intensive use while it is still structurally and economically viable.
 
Orbital Reef, led by Blue Origin and Sierra Space with partners including Boeing and Arizona State University, is pitched as a mixed‑use space business park for research, industry, and tourism in low Earth orbit. Its payload interfaces are designed to be backward‑compatible with ISS standards, allowing existing ISS experiment hardware to migrate to the new platform and preserving continuity of microgravity research. 
 
The ISS National Lab and partner agencies are explicitly trying to build a sustainable low Earth orbit economy, using current ISS access to mature space‑based business models and prepare for a post‑ISS research ecosystem. By 25 years from now, this trajectory points toward multiple commercially operated labs and industrial modules—pharmaceuticals, materials, biotech—serving government, academic, and private customers rather than a single monolithic station.
 
In parallel, agencies plan outposts beyond LEO, such as the lunar Gateway, to support Artemis‑class missions; these cislunar platforms will complement, not replace, low‑orbit stations as hubs for deep‑space exploration. The combined effect is a shift from one government‑run ISS to a distributed architecture of commercial LEO stations plus lunar‑orbit infrastructure, maintaining continuous human presence in space well past the ISS era.
 
The International Space Station (ISS) is humanity's most expensive object and has been in orbit for 25 years. Read its fascinating history, told in 25 numbers: https://www.bbc.com/news/topics/cvenzmgygy8t
 
 
References
Davis, J. (2024). The International Space Station, Humanity’s Shared Orbital Laboratory. The Planetary Society.
 
(2025, December 24). International Space Station. In Wikipedia, 
https://en.wikipedia.org/wiki/International_Space_Station
 
(2022). Station Benefits for Humanity. NASA. https://www.nasa.gov/international-space-station/space-station-research-and-technology/benefits-for-humanity/
 
(2021, December 2). NASA Selects Companies to Develop Commercial Destinations in Space. NASA. https://www.nasa.gov/news-release/nasa-selects-companies-to-develop-commercial-destinations-in-space/