Innovation in Focus: 25 Years of Continuous Human Presence in Space
The seven-member Expedition 64 crew gathers together for a New Year's Day portrait inside the International Space Station's "window to the world," the cupola.
Media Credit: NASA
A visual exploration of humans living and working in an orbiting laboratory
November 24, 2025 • By Amy Elkavich, Staff Writer
This month marks 25 years of continuous human presence onboard the International Space Station (ISSInternational Space Station)—an achievement that reflects the power of global collaboration in pursuit of knowledge that changes lives. Since its first crew arrived in 2000, the ISS has hosted more than 290 astronauts and supported more than 4,000 experiments, leading to breakthroughs in medicine, advanced materials, and space exploration.
Through the work of the ISS National Laboratory®, managed by CASIS®, researchers have leveraged this unique platform to drive innovations that improve healthcare, advance technology, and benefit humanity.
This photo essay celebrates all of the people, partnerships, and activities that have made 25 years in orbit possible. We honor the discoveries that have informed our understanding of our planet and ourselves. And with our eyes turned toward the future, we dream of what comes next.
Extravehicular Activity (EVA) to Assemble the ISS
NASANational Aeronautics and Space Administration astronaut Robert Curbeam, mission specialist, in the first of three planned sessions of extravehicular activity (EVA) in 2006, as construction of the ISS took place.
Media Credit: NASA
Approximately 160 spacewalks, or EVAs, by astronauts were performed between 2000 and 2011 to connect the modules—Unity, Zarya, Destiny, Columbus, Kibo, Nauka—requiring real-time troubleshooting.
First Long-Duration Crew on the ISS
Media Credit: NASA
On October 31, 2000, the Soyuz TM-31 spacecraft launched from Baikonur and officially docked with the ISS on November 2, 2000, marking the beginning of Expedition 1, the first long-duration crew onboard the station. Over the next four months, the crew activated the life-support systems, unpacked critical equipment, hosted resupply missions, and built the foundation for a continuous human presence in space, which has persisted ever since. This historic mission ushered in a new era of international cooperation and scientific discovery in low Earth orbit(Abbreviation: LEO) The orbit around the Earth that extends up to an altitude of 2,000 km (1,200 miles) from Earth’s surface. The International Space Station’s orbit is in LEO, at an altitude of approximately 250 miles..
Destiny Module Designated a U.S. National Laboratory
Installed manually by astronauts, the U.S. Destiny module added 41% more working volume for microgravityThe condition of perceived weightlessness created when an object is in free fall, for example when an object is in orbital motion. Microgravity alters many observable phenomena within the physical and life sciences, allowing scientists to study things in ways not possible on Earth. The International Space Station provides access to a persistent microgravity environment. R&D, enabling custom human-operated labs and experiments.
Media Credit: NASA
On the left is a wide-angle view inside Destiny, the first U.S. research module on the ISS, just after its hatch was opened in 2001. This milestone marked the beginning of decades of groundbreaking science in orbit. On the right, the same module years later and in full lab-mode, was designated as a national laboratory managed by the Center for the Advancement of Science in Space® (CASIS®).
Check out the history of the ISS National Lab in an interactive photo journey and timeline.
The Evolution of Space Travel
Seen here, Space Shuttle Atlantis, prior to its 33rd flight, the 37th shuttle mission to the space station, and the 135th and final mission of NASA's Space Shuttle Program.
Media Credit: NASA
Astronauts have traveled to the ISS using various spacecraft, starting with NASA’s Space Shuttle until its retirement in 2011. Soyuz capsules then became the primary transport, and today commercial vehicles like SpaceX’s Crew Dragon, Northrop Grumman’s CRS missions, and Boeing’s Starliner offer advanced technology, improved safety, and cost-effective access to space.
Everyone Needs a Ride
SpaceX Crew-3 launch in 2021.
Media Credit: NASA
More than 290 individuals from 26 countries have visited the ISS, and each of them might admit that in this case, it’s about the journey AND the destination! The ride to the ISS is just as monumental as living and working in space.
Launching to the space station is an intense experience, starting with powerful acceleration as rockets push astronauts beyond Earth’s atmosphere. During ascent, they feel strong G-forces pressing them into their seats until the engines cut off and weightlessness begins.
Adapting to Microgravity
NASA astronauts Jasmin Moghbeli (left) and Loral O’Hara during Expedition 70, a long-duration mission to the orbital laboratory that ran from September 2023 to April 2024.
Media Credit: NASA
In microgravity, the body quickly senses the absence of gravity—fluids shift toward the head, giving a puffy face feeling, and objects float freely. This sudden change requires astronauts to adapt their movements and rely on handholds to navigate, marking the start of life in a completely different environment.
Daily Exercise
NASA astronaut Leland Melvin, mission specialist, exercised using the advanced Resistive Exercise Device (aRED) while living and working on the ISS.
Media Credit: NASA
Exercise is critically important for astronauts living on the ISS because the microgravity environment causes muscles and bones to weaken over time due to the lack of normal weight-bearing activity. Without regular physical activity, astronauts can experience significant muscle atrophy and bone density loss, which can lead to long-term health issues and make returning to Earth’s gravity challenging.
Daily exercise routines, including resistance training and cardiovascular workouts, help maintain strength, endurance, and overall physical health, ensuring astronauts can perform their duties effectively and safely during their mission and after their return to Earth.
Counting (Floating) Sheep
NASA astronauts Thomas D. Jones and Mark L. Polansky, mission specialists, photographed during their sleep shift in the Destiny module on the ISS in 2001.
Media Credit: NASA
Astronauts keep a strict schedule and exercise for hours a day, so when it’s time to sleep, they adapt to the in-space environment. In fact, astronauts simply conduct their version of climbing into bed—strapping in—and get some quality rest. Astronauts also wear eye masks to reduce distraction, but more importantly, because they experience 16 sunrises and sunsets every 24 hours as the ISS orbits Earth. This constant light change makes it difficult to maintain a natural sleep cycle.
Representation on Station
The Expedition Five and Soyuz 5 Taxi crews pose for a group photo in the Zvezda Service Module on the ISS.
Media Credit: NASA
Expedition 5 included NASA flight engineer Peggy Whitson, who flew on June 5, 2002, and was the first woman to serve a long-duration assignment onboard the ISS. During her six-month stay, Whitson conducted a wide range of biological and physical-science experiments, helped maintain the station, and laid the groundwork for female leadership in space.
NASA’s Twins Study
Expedition 45/46 Commander, Astronaut Scott Kelly along with his brother, former Astronaut Mark Kelly.
Media Credit: NASA
The Kelly brothers’ Twins Study was a landmark project that compared NASA astronaut Scott Kelly’s year in space with his identical twin and retired NASA astronaut, Mark, on Earth. This research revealed how extended spaceflight impacts the human body, including changes in gene expression, immune function, and bone health. While most effects reversed after returning to Earth, the study provided critical insights for protecting astronauts on future long-duration missions, such as trips to Mars.
Conducting Research on Station
NASA astronaut Kate Rubins examines samples of heart cells using the Microgravity Glovebox on the ISS.
Media Credit: NASA
The ISS National Lab provides a unique environment that enables research impossible on the ground, advancing fields like medicine, biotechnology, materials science, and Earth observation. Scientists uncover space-based research insights that lead to new therapies, sustainable technologies, and innovations benefiting life on Earth—and astronauts are often conducting the work on station with guidance from the ground. Learn more about the research taking place in this photo, here.
The Future
The ISS orbiting Earth in 2010.
Media Credit: NASA
Research in low Earth orbit remains productive, with astronauts living and working on station for as long as the ISS is functional. Future plans include deorbiting the ISS in 2030, but for now, research benefiting life on Earth continues. Stay up to date on ISS National Lab activities, here.
