International Space Station is a large, inhabited Earth satellite that more than 15 nations are operating in space. The first part of the station was launched in 1998, and the first full-time crew—one American astronaut and two Russian cosmonauts—occupied the station in 2000.
The International Space Station (ISS) orbits Earth at an altitude of about 250 miles (400 kilometers). The orbit extends from 52° north latitude to 52° south latitude.
The station includes several large cylindrical sections called modules. Each module was launched from Earth separately, and astronauts and cosmonauts connected the sections in space. Eight solar panels supply more than 100 kilowatts of electric power to the station. The panels are mounted on a metal framework 360 feet (109 meters) long.
The United States and Russia provided most of the modules and other equipment. Canada built a mobile robot arm, which was installed in 2001. Other participants include Japan and the member nations of the European Space Agency (ESA). Brazil signed a separate agreement with the United States to provide equipment.
Dozens of flights of U.S. space shuttles and Russian rockets were necessary to complete the major components of the International Space Station. ESA and Japan developed supply vehicles to be launched on ESA’s Ariane 5 and Japan’s H-2A booster rockets. In 2008, NASA agreed to use commercially developed spacecraft to deliver people and supplies after the retirement of the space shuttle in 2011. In 2012, the SpaceX Dragon capsule became the first private spacecraft to carry supplies to the ISS. In 2020, SpaceX’s Crew Dragon capsule carried U.S. astronauts to the space station.
Missions.
The crew and scientists on Earth—using radio signals—operate laboratory equipment on the station. Some of the equipment measures the effects of space conditions, such as apparent weightlessness, on biological specimens—including the crew. Other equipment produces various materials, including protein crystals for medical research. Crystals grown in space have fewer imperfections than those grown on Earth and are therefore easier to analyze. Medical researchers will use results of protein analyses to determine which crystals to mass-produce on Earth.
The major value of having a space station is that all the equipment needs to be carried into space only once. Also, the station can be used again and again by visiting astronauts and cosmonauts. Scientists on Earth can analyze experimental results and modify follow-up investigations much more quickly than before. The station was designed to operate for at least 15 years. But it could last for decades if parts are repaired and replaced as they wear out or are damaged.
History.
The International Space Station is the ninth inhabited space station to orbit Earth. The first such stations, consisting of six models of the Soviet Salyut station and the U.S. Skylab, were launched in the 1970’s.
In 1986, the Soviet Union began operating Mir, the first space station to use a modular design. The Soviets developed a reliable, economical transportation system, based on Soyuz spacecraft, for the station. The system enabled them to deliver supplies, equipment, and crew members to Mir. Following the collapse of the Soviet Union in 1991, Russia took over the operation of Mir. Russian cosmonauts handled major breakdowns on the station, which was wearing out. In March 2001, Russia took Mir out of orbit and sent it plunging to Earth.
Russia had intended to construct a station known as Mir 2 in the 1990’s. The United States had planned to build a station called Freedom in partnership with space agencies in Europe, Canada, and Japan. But due to funding difficulties, the United States and Russia agreed in 1993 to build a combined station—the International Space Station.
To prepare for the project, shuttles flew to Mir from 1995 to 1998. United States astronauts served on board the Russian station as researchers for as long as six months.
Major delays occurred in the construction of the International Space Station due to cutbacks in funding by the Russian government. A Russian Proton rocket finally launched the first module in November 1998. The module was a Russian-built and United States-funded unit called Zarya or the FGB. Zarya means sunrise in Russian, and FGB stands for functional cargo block.
The second module, Unity, was built by the United States. The space shuttle Endeavour carried Unity into orbit in December 1998, and it was then joined to Zarya. Unity has six hatches. One is connected to Zarya, and others serve as connectors for other modules.
In July 2000, a Proton rocket launched the Russian-built Zvezda (Star), or Service Module. Zvezda has living and working quarters for astronauts and cosmonauts. The shuttles Atlantis and Discovery carried up several more pieces soon afterward. Those included a support truss for solar panels and a connecting unit called a Pressurized Mating Adapter (PMA). The PMA provided a docking port for shuttles. The modular design of the NASA components allowed them to be repositioned as the station grew.
The first full-time crew, known as Expedition One, arrived in a Soyuz in November 2000. The crew commander was astronaut William Shepherd, and the other members were cosmonauts Yuri Gidzenko and Sergei Krikalev.
The shuttle Atlantis carried the U.S.-built Destiny Laboratory Module to the station in February 2001. Over the next few months, Destiny was activated, and scientific research began. Also in 2001, two additional modules—a U.S. airlock and a Russian airlock and docking port—were added.
In April 2001, the first space tourist traveled as a passenger in a Soyuz capsule to the station. Dennis Tito, an investment consultant from California, purchased the trip for an undisclosed price. He trained in Moscow for six months and spent six days aboard the station. South African businessman Mark Shuttleworth became the second space tourist when he purchased a ride on a Soyuz mission launched in April 2002. Other Soyuz missions carried either a space tourist or an astronaut selected and sponsored by ESA.
The next stages of construction were to expand the station’s power and life-support systems to support a full-time crew of six or seven. To provide emergency return capability for a crew that large, NASA planned to build a seven-person escape craft. But during 2001, it became clear that NASA had greatly underestimated the cost of developing and operating the station. NASA’s cost for the station was about $5 billion over budget. As a result, NASA suspended the plan to enlarge the crew and build the escape craft.
In 2002, the station continued to operate with a crew of three. Space shuttles replaced the crew every four or five months. Russian cosmonauts also flew a new Soyuz spacecraft to the station every six months. The Soyuz would serve as a “bail-out capsule” in case of a life-threatening emergency. The expansion of the power system also continued.
On Feb. 1, 2003, the space shuttle Columbia broke apart on reentry into Earth’s atmosphere, killing all seven crew members. NASA halted shuttle flights until it could ensure the safety of future flights. Soyuz missions then began carrying crews to and from the station. The station’s crew was reduced to two people to conserve supplies normally carried to the station by shuttles.
Discovery, the next shuttle launched, visited the station in July and August 2005. The shuttle’s crew delivered supplies, performed repairs, and installed new equipment. Discovery also hauled away trash that had accumulated in the station during the halt in shuttle flights. Continuing safety concerns, however, led NASA to postpone further shuttle launches, and the station continued to operate with only two crew members. In July 2006, Discovery dropped off more supplies and an astronaut, returning the station’s crew to three.
In October 2007, the American astronaut Peggy Whitson became the first woman to command the station. Also in October, Discovery arrived with the Italian-built U.S. Harmony module, a compartment to link U.S., European, and Japanese modules.
In 2008, shuttles delivered Europe’s Columbus laboratory module and component modules for the Japanese Kibo laboratory. Astronauts also assembled a Canadian robot named Dextre designed to help with tasks outside the station. Also in 2008, Europe’s first Automated Transfer Vehicle (ATV) docked with the station.
In 2009, shuttle missions performed several tasks to prepare for an increase in the crew size of the station. These upgrades included adding two new solar panels to increase electrical power and a water recycling module that provides the crew with a steady supply of clean water. A crew expansion occurred on May 29, 2009, with the arrival of three new members, increasing the station’s crew to six people. Loading the player...
Launch of a Soyuz rocket in 2009
The space station reached two milestones in late 2010. On October 23, the station passed the Russian space station Mir as the longest continuously occupied spacecraft. Days later, on November 2, the station reached 10 years of continuous human habitation. Initial construction of the space station was completed in 2011, but future additions are planned. The final space shuttle mission was a flight to the station by the shuttle Atlantis in July 2011.
In 2012, the SpaceX Dragon capsule became the first private spacecraft ever to fly to the ISS. The capsule carried over 1,000 pounds (450 kilograms) of supplies to the station. Since then, SpaceX has made more than 20 flights carrying cargo to the ISS.
The Bigelow Expandable Activity Module (BEAM) was installed at the station in 2016. The sides of the module were made mostly of fabric, rather than rigid materials. A supply craft carried the BEAM to the station packed into a tight cylinder. ISS astronauts attached the module to the station and expanded it by filling it with air, somewhat like blowing up a balloon. The BEAM was developed by the American company Bigelow Aerospace to test the use of expandable modules in space.
In 2020, the SpaceX Crew Dragon capsule became the first private spacecraft ever to take astronauts into orbit. It carried two U.S. astronauts to the ISS.
The Russian-built Nauka module was added to the station in 2021. The multi-purpose module includes laboratory space and living quarters for astronauts.
