International Space Station Completes 25 Years of Human Presence
A Quarter-Century of ISS Visitors and Global Cooperation
The milestone of ISS visitors over 25 years marks one of humanity’s largest cooperative achievements in space. Roscosmos has confirmed that 290 individuals from 26 countries have travelled to the orbital laboratory since it became permanently inhabited. This diverse group of astronauts and cosmonauts has shaped scientific exploration, international partnerships, and technological evolution in low Earth orbit.
25 Years, 290 Visitors — A Global Human Footprint in Orbit
Roscosmos revealed that 239 men and 51 women have worked aboard the ISS to date. Their missions have contributed to space science, microgravity research, Earth observation, and technology testing that supports future deep-space exploration.
Breakdown of Manned Flights
Across the ISS programme, 125 manned flights have delivered crews and cargo to the station. These included:
- 71 Soyuz spacecraft missions
- 37 Space Shuttle flights
- 16 Crew Dragon missions
- 1 Boeing Starliner flight
Each spacecraft has expanded international participation and strengthened the station’s logistical backbone.
The ISS Beginning — From Zarya to Permanent Human Presence
The ISS story began on 20 November 1998, when the Zarya module was launched into orbit. This served as the functional foundation for the station. Over the next two years, the complex grew with the addition of the Unity and Zvezda modules, enabling early habitation systems.
The Historic ISS-1 Expedition
Permanent operations began on 2 November 2000, with the arrival of Soyuz TM-31. The first long-duration crew, known as ISS-1, included:
- Yury Gidzenko (Commander, Roscosmos)
- Sergey Krikalev (Roscosmos)
- William Shepherd (NASA), the first ISS Commander
Their mission started a continuous human presence in orbit that has now exceeded 25 years — a record in space history.
Current Crew and the Cross-Flight Programme
Today, the ISS hosts seven crew members who travel aboard Russia’s Soyuz MS and NASA–SpaceX’s Crew Dragonspacecraft.
Since 2022, the cross-flight programme ensures balanced cooperation:
Every US spacecraft going to the ISS must include one Roscosmos cosmonaut.
Every Russian spacecraft must carry one NASA astronaut.
This arrangement strengthens operational safety and maintains uninterrupted operations even if one fleet encounters delays.
Spacewalks Over 25 Years — A Record of Human Endurance
Human presence outside the ISS is equally historic. Roscosmos stated that 277 spacewalks (EVAs) have been completed:
75 from the Russian segment
202 from the US segment
Notable EVA Milestones
157 astronauts and cosmonauts from ten countries have performed spacewalks.
The longest EVA, lasting 8 hours and 56 minutes, was conducted in 2001 by James Voss and Susan Helms(NASA).
Michael Lopez-Alegria (NASA) holds the record for longest cumulative EVA duration.
These spacewalks have enabled upgrades, repairs, module installations, and essential science operations.
The ISS Across Time — International Science at 400 km Above Earth
For a quarter-century, the ISS has acted as a floating laboratory. It has hosted:
- Life sciences experiments
- Earth and climate monitoring
- Advanced materials research
- Studies on human adaptation to microgravity
- Technology testing for Moon and Mars missions
The ISS visitors over 25 years reflect unprecedented international collaboration, proving that scientific unity can exist even during geopolitical tensions.
The Legacy of 25 Years in Orbit
The International Space Station stands as a testament to global partnership and human resilience. With 290 visitors, hundreds of spacewalks, and thousands of scientific experiments, the ISS continues to shape the future of space exploration. As nations prepare for lunar bases and Mars missions, the lessons learnt over these 25 years will guide the next era of human discovery.
