International Space Station

The International Space Station (ISS) took 10 years and more than 30 missions to assemble. It is the result of unprecedented scientific and engineering collaboration among five space agencies representing 15 countries.

The space station is approximately the size of a football field: a 460-ton, permanently crewed platform orbiting 250 miles above Earth. It is about four times as large as the Russian space station Mir and five times as large as the U.S. Skylab.



President Reagan directs NASA to build the ISS January 25, 1984

President Ronald Reagan's State of the Union Address directs NASA to build an international space station within the next 10 years.

ISS Assembly

Early Assembly Flight Summaries

Zarya (sunrise) control module

Launched Nov. 20, 1998, from the Baikonur Cosmodrome, Kazakhstan, Zarya is providing the early propulsion, steering and communications for the station until Zvezda arrives. Afterward, Zarya is used as a passageway, stowage facility, docking port and fuel tank.



November 20, 1998

The first segment of the ISS launches: a Russian proton rocket named Zarya ("sunrise").


Unity Node

(Shuttle Mission STS-88)

The first wholly U.S. component was launched Dec. 4, 1998, aboard Space Shuttle Endeavour. Unity provides six docking ports, one on each side. With Zarya permanently attached to one of those, the remaining five will serve as attach points , to which all future U.S. modules will be joined.



December 4, 1998 Unity, the first U.S.-built component of the International Space Station

Logistics Flight

(Shuttle Mission STS-96)

Discovery launched May 27, 1999 and docked with the ISS two days later. Aboard was 2,000 pounds of supplies and logistics to prepare the orbiting facility with equipment that eventually will be used by crews that live aboard for long durations. It was the second shuttle mission dedicated to the assembly and outfitting of the station.

Maintenance/Logistics Flight

(Shuttle Mission STS-101)

Atlantis returned to space on May 19, 2000, following two years of upgrades. It’s cargo included more than 2,000 pounds of supplies and equipment to extend the lifetime of the Zarya module. During the mission, four of six batteries and associated electrical components were swapped to restore the electrical power system to full redundancy. This was the third shuttle flight for station assembly.

Zvezda service module

Zvezda will be the core of the Russian segment when launched in July 2000. The ISS performs an automatic rendezvous and docking with Zvezda, which provides living area, life support, navigation, propulsion and communications through the early assembly phases. It then will assume most of Zarya’s functions.

Logistics Flight

(Shuttle Mission STS-106)

Atlantis returns to the ISS after the arrival of the Zvezda to provide additional supplies and serve as the first opportunity for astronauts and cosmonauts to enter the newest module after it becomes a permanent part of the station. Crewmembers not only will unload supplies from the shuttle, but also from a recently docked Progress vehicle. The mission launched in September 2000.

Gyroscopes and Framework

(Shuttle Mission STS-92)

Launch of Discovery carrying the first small piece of truss structure and the station’s gyroscopes late September 2000. The Z1 truss (a piece of the girder-like truss), four Control Moment Gyros, and an additional conical docking adapter made up the cargo for this second major shuttle assembly mission.

The framework houses critical electronics and communications equipment, and the gyroscope systems that eventually will replace thrusters to maintain the station's stability.

The shuttle's robot arm will be used to attach the framework and docking adapter. Next, astronauts performed several spacewalks to make final connections.

First Crew

The Expedition One crew heads to the ISS in late November 2000 to begin the permanent human presence on the station. astronaut William Shepherd, and cosmonauts Yuri Gidzenko and Sergei Krikalev traveled to the station aboard a Russian Soyuz spacecraft from the Baikonur Cosmodrome, Kazakhstan.

Shepherd serves as the Expedition Commander, Gidzenko is the Soyuz Commander and Krikalev the Flight Engineer.

They will dock with the station two days after launch and begin a stay of about four months. Their mission will be to activate life support systems and experiments, while continuing stowage and checkout of the new station. They also will assist with the continuing assembly and conduct the first station-based spacewalks from Zvezda’s forward airlock.

The first crew returned to Earth on a shuttle, leaving the Soyuz that launched them docked at the station as an emergency "lifeboat" for the next crew.




 November 2, 2000

Astronaut Bill Shepherd and cosmonauts Yuri Gidzenko and Sergei Krikalev become the first crew to reside onboard the station.

The International Space Station established an unprecedented state-of-the-art laboratory complex in orbit, more than four times the size and with almost 60 times the electrical power for experiments — critical for research capability — of Russia's Mir.

Research in the station's six laboratories will lead to discoveries in medicine, materials and fundamental science that will benefit people all over the world.

Examples of the types of U.S. research that will be performed aboard the station include:

Protein crystal studies: More pure protein crystals may be grown in space than on Earth. Analysis of these crystals helps scientists better understand the nature of proteins, enzymes and viruses.

Tissue culture: Living cells can be grown in a laboratory environment in space where they are not distorted by gravity.

Flames, fluids and metal in space: Fluids, flames, molten metal and other materials will be the subject of basic research on the station.

Even flames burn differently without gravity. Reduced gravity reduces convection currents, the currents that cause warm air or fluid to rise and cool air or fluid to sink on Earth.

This absence of convection alters the flame shape in orbit and allows studies of the combustion process that are impossible on Earth.

The absence of convection allows molten metals or other materials to be mixed more thoroughly in orbit than on Earth.

Scientists plan to study this field, called Materials Science, to create better metal alloys and more perfect materials for applications such as computer chips.

The nature of space: Some experiments aboard the station will take place on the exterior of the station modules.

Such exterior experiments can study the space environment and how long-term exposure to space, the vacuum and the debris, affects materials.

This research can provide future spacecraft designers and scientists a better understanding of the nature of space and enhance spacecraft design.

Watching the Earth: Observations of the Earth from orbit help the study of large-scale, long-term changes in the environment.

Studies in this field can increase understanding of the forests, oceans and mountains. The effects of volcanoes, ancient meteorite impacts, hurricanes and typhoons can be studied.

In addition, changes to the Earth that are caused by the human race can be observed.

Commercialization: As part of the Commercialization of space research on the station, industries will participate in research by conducting experiments and studies aimed at developing new products and services.

The results may benefit those on Earth not only by providing innovative new products as a result, but also by creating new jobs to make the products.

Life in low gravity: The effects of long-term exposure to reduced gravity on humans – weakening muscles; changes in how the heart, arteries and veins work; and the loss of bone density, among others will be studied aboard the station. Studies of these effects may lead to a better understanding of the body’s systems and similar ailments on Earth. A thorough understanding of such effects and possible methods of counteracting them is needed to prepare for future long-term human exploration of the solar system.

The United States has the responsibility for developing and ultimately operating major elements and systems aboard the station.

The international partners, Canada, Japan, the

European Space Agency, and Russia, have contributed the key elements to the International Space Station:

In addition, Brazil and Italy are contributing some equipment to the station through agreements with the United States.