ISS – International Space Station: Purpose, Achievement

The International Space Station (ISS) is a modular space station (habitable artificial satellite) in low Earth orbit. The ISS programme is a multi-national collaborative project between five participating space agencies:

The ownership and use of the space station is established by intergovernmental treaties and agreements.

ISS Sections
International Space Station

The ISS serves as a micro-gravity and space environment research laboratory in which scientific experiments are conducted in astrobiology, astronomy, meteorology, physics, and other fields.

The station is suited for testing the spacecraft systems and equipment required for possible future long-duration missions to the Moon and Mars.

It is the largest artificial object in space and the largest satellite in low Earth orbit, regularly visible to the naked eye from Earth's surface.

It maintains an orbit with an average altitude of 400 kilometres (250 mi) by means of reboost manoeuvres using the engines of the Zvezda Service Module or visiting spacecraft. The ISS circles the Earth in roughly 93 minutes, completing 15.5 orbits per day.

The station is divided into two sections: the Russian Orbital Segment (ROS), operated by Russia; and the United States Orbital Segment (USOS), which is shared by many nations. Roscosmos has endorsed the continued operation of ISS through 2024, but had previously proposed using elements of the Russian segment to construct a new Russian space station called OPSEK. As of December 2018, the station is expected to operate until 2030.

The first ISS component was launched in 1998, with the first long-term residents arriving on 2 November 2000. Since then, the station has been continuously occupied for 19 years and 215 days.

This is the longest continuous human presence in low Earth orbit, having surpassed the previous record of 9 years and 357 days held by the Mir space station. The latest major pressurized module was fitted in 2011, with an experimental inflatable space habitat added in 2016.

Development and assembly of the station continues, with several major new Russian elements scheduled for launch starting in 2020. The ISS consists of pressurized habitation modules, structural trusses, photovoltaic solar arrays, thermal radiators, docking ports, experiment bays and robotic arms. Major ISS modules have been launched by Russian Proton and Soyuz rockets and US Space Shuttles.

The ISS is the ninth space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz, and Mir stations as well as Skylab from the US.

The station is serviced by a variety of visiting spacecraft: the Russian Soyuz and Progress, the US Dragon and Cygnus, the Japanese H-II Transfer Vehicle, and formerly the European Automated Transfer Vehicle.

The Dragon spacecraft allows the return of pressurized cargo to Earth (downmass), which is used, for example, to repatriate scientific experiments for further analysis. The Soyuz return capsule has minimal down-mass capability next to the astronauts.

As of September 2019, 239 astronauts, cosmonauts, and space tourists from 20 different nations have visited the space station, many of them multiple times. The United States sent 151 people, Russia sent 47, nine were Japanese, eight Canadian, five Italian, four French, three German, and one each from Belgium, Brazil, Denmark, Kazakhstan, Malaysia, the Netherlands, South Africa, South Korea, Spain, Sweden, the United Arab Emirates, and the United Kingdom.

ISS Total Cost


Key Description:

Speed on Orbit: 7.66 km/s

View on Maps:

Orbit Height: 408 km

Length: 73.0 m (239.4 ft)

Width: 109.0 m (357.5 ft)

Cost: 15,000 crores USD

Call Sign: Alpha, Station

Crew Fully crewed: 6

Currently aboard: 5

Launch: 20 November 1998

Mass: 419,725 kg (925,335 lb)

Length: 73.0 m (239.4 ft)

Width: 109.0 m (357.5 ft)

Pressurised volume: 915.6 m3 (32,333 cu ft)

Atmospheric Pressure 101.3 kPa (14.7 psi; 1.0 atm), Oxygen 21%, nitrogen 79%

Perigee Altitude: 408 km (253.5 mi) AMSL

Apogee Altitude: 410 km (254.8 mi) AMSL

Orbital Inclination: 51.64°

Orbital Speed 7.66 km/s
(27,600 km/h; 17,100 mph)

Orbital Period 92.68 minutes

Orbits Per Day: 15.54

Orbit Epoch: 14 May 2019 13:09:29 UTC

Days in Orbit: 21 years, 6 months, 15 days
(4 June 2020)

Days Occupied: 19 years, 7 months, 2 days
(4 June 2020)

No. of Orbits: 116,178 as of May 2019
Orbital decay 2 km/month



The ISS was originally intended to be a laboratory, observatory, and factory while providing transportation, maintenance, and a low Earth orbit staging base for possible future missions to the Moon, Mars, and asteroids.

However, not all of the uses envisioned in the initial memorandum of understanding between NASA and Roscosmos have come to fruition.

In the 2010 United States National Space Policy, the ISS was given additional roles of serving commercial, diplomatic, and educational purposes.


Mission Controls:

The components of the ISS are operated and monitored by their respective space agencies at mission control centres across the globe, including:

Roscosmos's Mission Control Center at Korolyov, Moscow Oblast, controls the Russian Orbital Segment which handles Guidance, Navigation and Control for the entire Station, in addition to individual Soyuz and Progress missions.

ESA's ATV Control Centre, at the Toulouse Space Centre (CST) in Toulouse, France, controls flights of the uncrewed European Automated Transfer Vehicle.

JAXA's JEM Control Center and HTV Control Center at Tsukuba Space Center (TKSC) are responsible for operating the Kibō complex and all flights of the White Stork HTV Cargo spacecraft, respectively.

NASA's Mission Control Center at Lyndon B. Johnson Space Center in Houston, Texas, serves as the primary control facility for the United States segment of the ISS.

NASA's Payload Operations and Integration Center at Marshall Space Flight Center in Huntsville, Alabama, coordinates payload operations in the USOS.

ESA's Columbus Control Centre at the German Aerospace Center in Oberpfaffenhofen, Germany, manages the European Columbus research laboratory.[6]

CSA's MSS Control at Saint-Hubert, Quebec, Canada, controls and monitors the Mobile Servicing System, or Canadarm2.


International co-operation:

Involving five space programs and fifteen countries,the International Space Station is the most politically and legally complex space exploration program in history.

The 1998 Space Station Intergovernmental Agreement sets forth the primary framework for international cooperation among the parties.

A series of subsequent agreements govern other aspects of the station, ranging from jurisdictional issues to a code of conduct among visiting astronauts.

Participating countries:

European Space Agency:

  • Belgium
  • Denmark
  • France
  • Germany
  • Italy
  • Netherlands
  • Norway
  • Spain
  • Sweden
  • Switzerland
  • United Kingdom



The ISS has been described as the most expensive single item ever constructed. As of 2010 the total cost was US$150 billion.

This includes NASA's budget of $58.7 billion (inflation-unadjusted) for the station from 1985 to 2015 ($72.4 billion in 2010 dollars),

Russia's $12 billion, Europe's $5 billion, Japan's $5 billion, Canada's $2 billion, and the cost of 36 shuttle flights to build the station, estimated at $1.4 billion each, or $50.4 billion in total.

Assuming 20,000 person-days of use from 2000 to 2015 by two- to six-person crews, each person-day would cost $7.5 million, less than half the inflation-adjusted $19.6 million ($5.5 million before inflation) per person-day of Skylab.