The International Space Station as it was configured on August 20, 2001, Credit: NASA

The largest and most complex international construction project in space began on the steppes of Kazakhstan 20 years ago today. Atop its Proton rocket, on Nov. 20, 1998, the Zarya Functional Cargo Block thundered off its launch pad at the Baikonur Cosmodrome to serve as a temporary control module for the nascent International Space Station. Nine minutes later, Zarya was in orbit and began unfurling its antennas and solar panels, seemingly coming alive in the airless environment of low Earth orbit. The launch of the first element of the Space Station kicked off an incredible journey of orbital assembly, operations and science.

For two decades, the International Space Station has been circling the Earth every 90 minutes from an orbit of approximately 250 miles. The ISS has been humanity’s platform to learn about living in space, as well as observing the Earth and performing research that has benefited us here on terra firma.

It is a unique place – a convergence of science, technology and human innovation that demonstrates new technologies and makes research breakthroughs not possible on Earth. It is a microgravity laboratory in which an international crew of three to six people live and work while traveling at a speed of five miles per second, orbiting Earth every 90 minutes.

The space station has been continuously occupied since November 2000. In that time, 222 people from 18 countries have visited. Crew members spend about 35 hours each week conducting research in many disciplines to advance scientific knowledge in Earth, space, physical, and biological sciences for the benefit of people living on our home planet.

An international partnership of space agencies provides and operates the elements of the ISS. The principals are the space agencies of the United States, Russia, Europe, Japan, and Canada. The ISS has been the most politically complex space exploration program ever undertaken. The ISS Program brings together international flight crews, multiple launch vehicles, globally distributed launch, operations, training, engineering, and development facilities; communications networks, and the international scientific research community.

Elements launched from different countries and continents are not mated together until they reach orbit, and some elements that have been launched later in the assembly sequence were not yet built when the first elements were placed in orbit. Each partner has the primary responsibility to manage and run the hardware it provides. Construction, assembly and operation of the International Space Station requires the support of facilities on the Earth managed by all of the international partner agencies and countries involved in the program.

The space station remains the springboard to NASA’s next great leap in exploration, enabling research and technology developments that will benefit human and robotic exploration of destinations beyond low-Earth orbit, including asteroids and Mars. It is the blueprint for global cooperation – one that enables a multinational partnership and advances shared goals in space exploration.

As a collection of modules and components assembled piece by piece, the ISS has been an active construction project for its entire existence. Transformed over and over again with the arrival of new modules and solar arrays, the space station has been reconfigured by astronauts nearly as often as a child’s building block set.

We’ve put together a gallery of 20 photos showing some of the various assemblies of the International Space Station throughout the past 20 years. Enjoy.

Two decades in space and counting

An international mating – December 7, 1988

Astronauts from the Space Shuttle mission STS-88 work on the embryonic International Space Station, hours after connecting the first element – the Russian-built Zarya FGB control module with the American built Node 1 Unity module in December 1998. The crew carried a large-format IMAX camera from which this picture was taken. NASA astronaut James Newman is working on communication cables on Unity while fellow crew member Jerry Ross monitors his progress.

Preparing a new home – September 18, 2000

The International Space Station as seen from the departing Space Shuttle Atlantis following the arrival of the Russian Zvezda Service Module to the orbital complex. In view from top to bottom are the Unity Module, the Zarya FGB, the Zvezda SM and the docked Progress M1-3 spacecraft. During the course of the mission, the STS-106 crew readied the station for permanent occupation by outfitting it in preparation for the arrival of its first residents, the three-person Expedition 1 crew, which launched aboard Soyuz TM-31 on October 31, 2000.

Powering up with solar energy – December 5, 2000

Astronaut Carlos I. Noriega, mission specialist, waves during the second of three spacewalks on STS-97. During the 11-day mission, the Space Shuttle crew delivered and connected the first set of U.S. solar arrays to the International Space Station. The astronauts completed three spacewalks in total, during which they prepared a docking port for arrival of the Destiny Laboratory Module, installed Floating Potential Probes to measure electrical potential surrounding the station, installed a camera cable outside the Unity Module, and transferred supplies, equipment and refuse between Endeavour and the ISS.

Departing glow – March 18, 2001

The International Space Station backdropped against black space was photographed with a digital still camera from the Space Shuttle Discovery on March 18, 2001. It was a standard practice for the shuttle to make a final fly-around of the outpost following unlinking from it. The mission’s main purpose was to swap the Expedition 1 and Expedition 2 crews, as well as resupply the ISS. It also marked the first use of the Multi Purpose Logistics Module (Leonardo) to bring supplies to the station.

Extending the backbone – December 2, 2002

A panoramic view of the International Space Station from the departing Space Shuttle on mission STS-113. During the 14-day mission, Endeavour and its crew extended the ISS backbone with the P1 truss and exchanged the Expedition 5 and Expedition 6 crews aboard the station.

Return to flight – August 6, 2005

Backdropped by a colorful Earth, this aft zenith view of the International Space Station was photographed during the flyaround by the Space Shuttle Discovery following the undocking of the two spacecraft. Discovery pulled away from the complex at 2:24 a.m. CDT on August 6, 2005. The view in the background is over the North Caspian Sea and Kazakhstan. The STS-114 mission delivered supplies to the ISS and marked the return to flight of the Space Shuttle fleet after the Columbia disaster. Seventeen years prior, Discovery had flown NASA’s previous Return to Flight mission, STS-26.

Find the spacewalkers – September 6, 2006

This panoramic scene of the International Space Station over terrain could be used for a quick game of “find the two astronauts in this picture.” The combined crews of the Space Shuttle Atlantis and the orbital outpost have resumed construction on the station this week. The two STS-115 crew members in this picture were participating in the second of three scheduled space walks. Astronaut Daniel C. Burbank can be recognized by the broken red stripe on each leg of his extravehicular mobility space suit. Not so readily visible is astronaut Steven G. MacLean, representing the Canadian Space Agency, just above and to the right of Burbank. Atlantis left the station with a new, second pair of 240-foot solar wings, attached to a new 17.5-ton section of truss with batteries, electronics and a giant rotating joint.

Beefing up the ISS – June 19, 2007

Backdropped by the blackness of space and Earth’s horizon, the International Space Station moves away from the Space Shuttle Atlantis. Earlier the STS-117 and Expedition 15 crews concluded about eight days of cooperative work onboard the shuttle and station. Atlantis and crew delivered the second and third starboard truss segments and another pair of solar arrays to the space station. Astronaut Lee Archambault, STS-117 pilot, was at the controls for the departure and fly-around, which gave Atlantis’ crew a look at the station’s new expanded configuration.

Workplace with an ocean view – August 15, 2007

Astronaut Rick Mastracchio, STS-118 mission specialist, participates in the mission’s third planned spacewalk or extravehicular activity (EVA) on Aug. 15, 2007, as construction and maintenance continue on the International Space Station. During the 5-hour, 28-minute spacewalk, Mastracchio and astronaut Clay Anderson (out of frame), Expedition 15 flight engineer, relocated the S-Band Antenna Sub-Assembly from Port 6 (P6) to Port 1 (P1) truss, installed a new transponder on P1 and retrieved the P6 transponder.

Home away from home – March 23, 2008

Flyaround view of the International Space Station taken from Space Shuttle Endeavor after undocking. STS-123 was the twenty-fifth shuttle mission to visit the ISS, and delivered the Japanese Experiment Module (Kibō), and the Canadian Special Purpose Dexterous Manipulator, Dextre robotics system, to the station. The mission duration was 15 days and 18 hours. It was the first mission to fully utilize the Station-to-Shuttle Power Transfer System, allowing ISS power to augment the orbiter’s power systems. The mission set a record for a Space Shuttle’s longest stay at the ISS.

See the ISS pass overheard

More than an acre of solar arrays provide power to the space station, and also make it the second brightest object in the night sky after the Moon. You don’t even need a telescope to see it zoom over your house. You can have a text message or email alert sent to let you know when (and where) to look up, spot the station, and wave!

Visible to the naked eye, the ISS looks like a plane only much higher and traveling thousands of miles an hour faster!

Get email or text alerts when the space station is flying over.

https://spotthestation.nasa.gov

Soaring above the clouds – September 8, 2009

Backdropped by Earth’s horizon and the blackness of space, the International Space Station is seen from Space Shuttle Discovery as the two spacecraft begin their relative separation. Earlier the STS-128 and Expedition 20 crew concluded nine days of cooperative work onboard the Space Shuttle and the ISS. Discovery carried the Multi-Purpose Logistics Module Leonardo as its primary payload. Leonardo contained a collection of experiments for studying the physics and chemistry of microgravity. The Space Shuttle also flew the first test flight of the TriDAR, a 3D dual-sensing laser camera, intended for potential use as an autonomous rendezvous and docking sensor. STS-128 was the final Space Shuttle flight used for ISS crew rotation.

Earthgazing from the cupola – September 11, 2010

NASA astronaut Tracy Caldwell Dyson, Expedition 24 flight engineer, looks through a window in the Cupola of the International Space Station. A blue and white part of Earth and the blackness of space are visible through the windows. The image was a self-portrait using natural light.

Unique perspective – May 23, 2011

This image of the International Space Station and the docked space shuttle Endeavour, flying at an altitude of approximately 220 miles, was taken by Expedition 27 crew member Paolo Nespoli from the Soyuz TMA-20 following its undocking on May 23, 2011. The pictures are the first taken of a shuttle docked to the International Space Station from the perspective of a Russian Soyuz spacecraft. Onboard the Soyuz were Russian cosmonaut and Expedition 27 commander Dmitry Kondratyev; Nespoli, a European Space Agency astronaut; and NASA astronaut Cady Coleman. Coleman and Nespoli were both flight engineers. The three landed in Kazakhstan later that day, completing 159 days in space.

Credit: NASA/Lee Brandon-Cremer (CC BY-SA 3.0)

Last call for the Space Shuttle – July 12, 2011

Flight day five of the final Space Shuttle mission, and the last servicing call to the ISS, saw Expedition 28 Flight Engineers Mike Fossum and Ron Garan perform a spacewalk. Because of a short training flow and a requirement to launch the Atlantis orbiter with a reduced crew of four, NASA opted not to utilize two spacewalkers from the STS-135 crew. The main tasks for the spacewalk included retrieving a failed pump module from an external stowage platform of the ISS for return to Earth inside the orbiter’s cargo bay, installing two experiments and repairing a new base for the station’s robotic arm.

Relocation for future expansion – February 16, 2012

Russian cosmonauts Oleg Kononenko and Anton Shkaplerov, both Expedition 30 flight engineers, participate in a session of extravehicular activity (EVA) to continue outfitting the International Space Station. During the six-hour, 15-minute spacewalk, Kononenko and Shkaplerov moved the Strela-1 crane from the Pirs Docking Compartment to begin preparing the Pirs for its replacement next year with a new laboratory and docking module. The duo used another boom, the Strela-2, to move the hand-operated crane to the Poisk module for future assembly and maintenance work. Both telescoping booms extend like fishing rods and are used to move massive components outside the station. On the exterior of the Poisk Mini-Research Module 2 (MRM2), they also installed the Vinoslivost Materials Sample Experiment, which will investigate the influence of space on the mechanical properties of the materials. The spacewalkers also collected a test sample from underneath the insulation on the Zvezda Service Module to search for any signs of living organisms. Both spacewalkers wore Russian Orlan spacesuits bearing blue stripes and equipped with NASA helmet cameras.

Out of this world maintenance – November 9, 2013

Russian cosmonaut Oleg Kotov, Expedition 37 flight engineer, attired in a Russian Orlan spacesuit, participates in a session of extravehicular activity (EVA) in support of assembly and maintenance on the International Space Station. During the five-hour, 50-minute spacewalk, Kotov and Russian cosmonaut Sergey Ryazanskiy (out of frame) continued the setup of a combination EVA workstation and biaxial pointing platform that was installed during an Expedition 36 spacewalk on Aug. 22.

Studying the Earth – September 29, 2014

Tthe RapidScat Nadir Adapter is removed from the SpaceX-4 Dragon trunk and installed onto the Columbus Exposed Facility Unit (EFU). ISS-RapidScat is a space-based scatterometer that replaces the inoperable SeaWinds payload aboard the QuickSCAT satellite. Scatterometers are radar instruments that measure wind speed and direction over the ocean, and are useful for weather forecasting, hurricane monitoring, and observations of large-scale climate phenomena such as El Niño. The ISS RapidScat instrument enhances measurements from other international scatterometers by cross-checking their data, and demonstrates a unique way to replace an instrument aboard an aging satellite.

Earth as a nightlight – July 25 2015

Night Earth observation of Japan taken by Expedition 44 crewmember Scott Kelly, with a Soyuz Spacecraft connected to the Mini Research Module 1 (MRM1), and a Progress Spacecraft visible. Kelly posted this photo to Twitter on July 25 with the caption, “#Goodevening #Japan. Showing @Astro_Kimiya how to take pictures of #Earth at night. #YearInSpace.”

Resupplying the ISS – November 19, 2018

Northrop Grumman’s Cygnus space freighter with its prominent cymbal-shaped UltraFlex solar arrays is pictured in the grips of the Canadarm2 robotic arm after it was captured by Expedition 57 Flight Engineer Serena Auñón-Chancellor and ESA astronaut Alexander Gerst.

A journey of knowledge – October 4, 2018

The International Space Station photographed by Expedition 56 crew members from a Soyuz spacecraft after undocking. NASA astronauts Andrew Feustel and Ricky Arnold and Roscosmos cosmonaut Oleg Artemyev executed a fly around of the orbiting laboratory to take pictures of the station before returning home after spending 197 days in space. In this image from October 2018, the fully completed station continues its mission to conduct microgravity research and experiments — ranging from human physiology to astronomy aboard humanity’s only orbital laboratory.

International Space Station Facts

230 individuals from 18 countries have visited the International Space Station.
The space station has been continuously occupied since November 2000.
An international crew of six people live and work while traveling at a speed of five miles per second, orbiting Earth about every 90 minutes.
In 24 hours, the space station makes 16 orbits of Earth, traveling through 16 sunrises and sunsets.
Peggy Whitson set the record for spending the most total time living and working in space at 665 days on Sept. 2, 2017.
The acre of solar panels that power the station means sometimes you can look up in the sky at dawn or dusk and see the spaceship flying over your home, even if you live in a big city. Find sighting opportunities at http://spotthestation.nasa.gov.
The living and working space in the station is larger than a six-bedroom house (and has six sleeping quarters, two bathrooms, a gym, and a 360-degree view bay window).
To mitigate the loss of muscle and bone mass in the human body in microgravity, the astronauts work out at least two hours a day.
Astronauts and cosmonauts have conducted more than 205 spacewalks (and counting!) for space station construction, maintenance and repair since December 1998.
The solar array wingspan (240 feet) is about the same length as the world’s largest passenger aircraft, the Airbus A380.
The large modules and other pieces of the station were delivered on 42 assembly flights, 37 on the U.S. space shuttles and five on Russian Proton/Soyuz rockets.
The space station is 357 feet end-to-end, one yard shy of the full length of an American football field including the end zones.
Eight miles of wire connects the electrical power system aboard the space station.
The 55-foot robotic Canadarm2 has seven different joints and two end-effectors, or hands, and is used to move entire modules, deploy science experiments and even transport spacewalking astronauts.
Six spaceships can be connected to the space station at once.
A spacecraft can arrive at the space station as soon as six hours after launching from Earth.
Four different cargo spacecraft deliver science, cargo and supplies: Orbital ATK’s Cygnus, SpaceX’s Dragon, JAXA’s HTV, and the Russian Progress.
Through Expedition 52, the microgravity laboratory has hosted more than 2,400 research investigations from researchers in more than 103 countries.
The station’s orbital path takes it over 90 percent of the Earth’s population, with astronauts taking millions of images of the planet below. Check them out at https://eol.jsc.nasa.gov.
More than 20 different research payloads can be hosted outside the station at once, including Earth sensing equipment, materials science payloads, particle physics experiments like the Alpha Magnetic Spectrometer-02 and more.
The space station travels an equivalent distance to the Moon and back in about a day.
The Water Recovery System reduces crew dependence on water delivered by a cargo spacecraft by 65 percent – from about 1 gallon a day to a third of a gallon.
On-orbit software monitors approximately 350,000 sensors, ensuring station and crew health and safety.
The space station has an internal pressurized volume equal that of a Boeing 747.
More than 50 computers control the systems on the space station.
More than 3 million lines of software code on the ground support more than 1.5 million lines of flight software code.
In the International Space Station’s U.S. segment alone, more than 1.5 million lines of flight software code run on 44 computers communicating via 100 data networks transferring 400,000 signals (e.g. pressure or temperature measurements, valve positions, etc.).

International Space Station Size & Mass

Pressurized Module Length: 240 feet (73 meters)
Truss Length: 357.5 feet (109 meters)
Solar Array Length: 239.4 feet (73 meters)
Mass: 925,335 pounds (419,725 kilograms)
Habitable Volume: 13,696 cubic feet (388 cubic meters) not including visiting vehicles
Pressurized Volume: 32,333 cubic feet (916 cubic meters)
With BEAM expanded: 32,898 cubic feet (932 cubic meters)
Power Generation: 8 solar arrays provide 75 to 90 kilowatts of power
Lines of Computer Code: approximately 2.3 million