The International Space Station Marks 25 Years of Continuous Human Presence
The International Space Station Marks 25 Years of Continuous Human Presence
The First Expedition
On November 2, 2000, the International Space Station (ISS) welcomed its first crew, marking the beginning of a new era in space exploration. The Expedition 1 crew, consisting of NASA astronaut William M. Shepherd and Russian cosmonauts Yuri P. Gidzenko and Sergei K. Krikalev, launched from the Baikonur Cosmodrome in Kazakhstan two days prior. After a successful docking, the crew transferred aboard the station and began bringing it to life. Their primary tasks during their four-month mission included installing and activating the life support and communications systems and working with three visiting space shuttle crews to continue the station's assembly. The trio returned to Earth in March 2001 aboard space shuttle Discovery, after having turned the station over to the Expedition 2 crew.
(Space)walking into History
Assembly and maintenance of the International Space Station would not be possible without the skilled work of crew members performing intricate tasks, in bulky spacesuits, in the harsh environment of space. In addition to station upkeep, spacewalks provide a platform for testing and improving spacesuits and tools – critical information for future exploration of the Moon and Mars. Other spacewalks have included operations for scientific research. In January 2025, for example, crew members collected samples for an investigation examining whether microorganisms have exited through station vents and can survive in space, to better inform spacecraft design that helps prevent human contamination of Mars and other destinations.
More than 270 spacewalks dedicated to the space station have been accomplished in the last quarter century. Several made station and human spaceflight history:
- May 1999: NASA astronaut Tamara Jernigan became the first woman to complete a spacewalk at the space station, in support of its construction.
- September 2000: Also during space station assembly, NASA astronaut Edward T. "Ed" Lu and Roscosmos cosmonaut Yuri I. Malenchenko conducted the first U.S.-Russian spacewalk.
- March 10, 2001: NASA astronauts James Voss and Susan Helms set the record for longest spacewalk in U.S. history, at 8 hours and 56 minutes.
- February 26, 2004: NASA astronaut Mike Foale and Russian cosmonaut Aleksandr Y. Kaleri complete the first spacewalk with no one inside the station.
- October 18, 2019: The first all-female spacewalk in history, conducted by NASA astronauts Christina Koch and Jessica Meir.
Orbiting Laboratory Welcomes First Commercial Crew
The International Space Station welcomed its first commercial crew members on May 31, 2020, when former NASA astronauts Robert Behnken and Douglas Hurley joined Expedition 63 Commander and NASA astronaut Chris Cassidy and Roscosmos cosmonauts Anatoly Ivanishin and Ivan Vagner aboard the orbiting laboratory. Behnken and Hurley lifted off from Kennedy Space Center in Florida the day before on NASA's SpaceX Demo-2 test flight – the first launch of American astronauts from U.S. soil since the space shuttle's retirement in 2011. The duo quickly integrated with the rest of the crew and participated in a number of scientific experiments, spacewalks, and public engagement events during their 62 days aboard station. Overall, the pair spent 64 days in orbit, completed 1,024 orbits around Earth, and contributed more than 100 hours of time to supporting the orbiting laboratory's investigations before splashing down on August 2.
Frank Rubio's Record-Breaking Year in Space
On September 27, 2023, NASA astronaut Frank Rubio returned to Earth after spending 371 days aboard the International Space Station—the longest single spaceflight by a U.S. astronaut in history. His mission surpassed the previous record of 355 days, set by NASA astronaut Mark Vande Hei, and provided scientists with an unprecedented look at how the human body adapts to more than a year in microgravity. Rubio's record-setting mission supported six human research studies, including investigations into diet, exercise, and overall physiology and psychology. He was the first astronaut to test whether limited workout equipment could still maintain health and fitness, an important consideration for future spacecraft with tighter living quarters.
A Global Foundation for Growing a Low Earth Orbit Economy
The space station is one of the most ambitious international collaborations ever attempted. It brings together international flight crews, multiple launch vehicles, globally distributed launch and flight operations, training, engineering, and development facilities, communications networks, and the international scientific research community for the benefit of all humanity. An international partnership of space agencies operates the elements of the orbiting laboratory: NASA, Roscosmos, ESA (European Space Agency), JAXA (Japan Aerospace Exploration Agency), and CSA (Canadian Space Agency). Each partner takes primary responsibility for managing and running the station hardware it provides, as well as on-Earth construction, launch support, mission operations, communications, and research and technology facilities that support the station.
At least 290 individuals representing 26 countries, and the five international partners have visited the orbiting laboratory during its 25 years of continuous human presence. Some of those visitors flew to the station on private astronaut missions. These missions contribute to scientific, outreach, and commercial activities. They also help demonstrate the demand for future commercial space stations and are an important component of NASA's strategy for enabling a robust and competitive commercial economy in low Earth orbit.
Implications and Future Directions
The International Space Station has proven to be a valuable platform for scientific research, technological development, and international cooperation. As we look to the future, the ISS will continue to play a crucial role in advancing our understanding of space and its applications. The lessons learned from the ISS will also inform the development of future space stations, such as the Gateway, which will serve as a base for lunar missions and provide a stepping stone for further human exploration of the solar system.
The ISS has also demonstrated the potential for commercial space stations to provide a sustainable and reliable presence in low Earth orbit. As the ISS approaches the end of its operational life, it is likely that commercial space stations will become the norm, providing a platform for a wide range of activities, from scientific research to space tourism.
In conclusion, the International Space Station has marked 25 years of continuous human presence in space, a testament to the ingenuity and cooperation of the international space community. As we look to the future, we can expect the ISS to continue to play a vital role in advancing our understanding of space and its applications, and paving the way for even greater achievements in space exploration and development.
