International Space Station (ISS)

📷 NASA / Wikimedia Commons (Public domain)

The International Space Station is the largest structure humans have ever assembled in space: a 420-tonne orbiting laboratory spanning 109 m across its solar wings — about the size of a football field — built and run by the space agencies of the United States, Russia, Europe, Japan, and Canada. It circles Earth roughly 400 km up at 28,000 km/h, one lap every 90 minutes, and has hosted people without a single day’s interruption since November 2, 2000.

More than 270 visitors from over 20 countries have lived and worked aboard, running thousands of experiments that range from growing protein crystals to hunting antimatter. It is widely reckoned the most expensive object ever built, with lifetime costs generally put above $150 billion.

Development History

The station fused two rival plans. NASA’s Space Station Freedom and Russia’s Mir-2, both stalled after the Cold War, were merged in 1993 into a single project joined by Europe, Japan, and Canada — fifteen nations in all, with former adversaries suddenly building one machine.

Assembly began on November 20, 1998, when Russia’s Zarya module reached orbit on a Proton rocket; two weeks later the Shuttle delivered NASA’s Unity node and astronauts bolted the pieces together. The Zvezda service module arrived in 2000 to make the outpost livable, and that November, Expedition 1 — Bill Shepherd, Yuri Gidzenko, and Sergei Krikalev — moved in. Nobody has turned the lights off since.

More than 40 assembly flights followed over 13 years: the Destiny lab in 2001, Europe’s Columbus and Japan’s Kibo labs in 2008, and truss segment after truss segment until the main structure was complete around 2011. Russia added its Nauka lab as late as 2021.

Design & Capabilities

The ISS stretches 109 m across its main truss and about 73 m along its chain of pressurized modules, which together enclose roughly 900 cubic metres — living and working room comparable to a six-bedroom house, shared by a typical crew of seven. Eight paired solar wings, reinforced since 2021 by new roll-out arrays, generate on the order of 100 kW.

Because thin traces of atmosphere drag it down, the station must be reboosted regularly by Zvezda’s engines or docked cargo ships. Crews arrive by Crew Dragon and Soyuz; supplies come up on Progress, Cygnus, and cargo Dragon vehicles. Two robotic arms — the 17.6-metre Canadarm2 and Europe’s newer ERA — move cargo, equipment, and even spacewalking astronauts around the exterior.

Over 270 spacewalks have gone into building and maintaining the outpost, making the ISS not just a laboratory but the deepest reservoir of experience humanity has in working outside a spacecraft.

Life On Board & Operations

Crews live on Greenwich time: about six and a half hours of science and maintenance daily, two hours of mandatory exercise to fight bone and muscle loss, and sixteen sunrises every 24 hours. Water is recycled — including from sweat and urine — at better than 90 percent recovery, and sleep happens in phone-booth-sized cabins. Research spans fluid physics, flames, immune cells, station-grown lettuce, and the Alpha Magnetic Spectrometer’s search for antimatter outside the hull.

Mission control centers in Houston and Moscow run the station around the clock, with support rooms in Germany, Japan, and Canada. The partners have committed to operations until about 2030, and NASA has contracted SpaceX to build a deorbit vehicle that will eventually steer the station to a controlled breakup over a remote stretch of ocean, clearing the way for commercial successors.

Frequently Asked Questions

How fast does the ISS travel?

About 28,000 km/h, or 7.7 km every second — fast enough to cross the United States in around ten minutes. At that speed it completes an orbit roughly every 92 minutes, giving the crew sixteen sunrises and sunsets a day. Counterintuitively, that blistering pace is exactly what keeps the station falling around Earth instead of onto it.

Can you see the ISS from Earth?

Yes, easily, and with no equipment at all. Around dawn and dusk the station catches sunlight while the ground below is dark, appearing as a bright, steady star gliding across the sky in a few minutes — at its best it outshines everything except the Sun and Moon. NASA’s Spot the Station service lists pass times for any location.

How long do astronauts stay on the ISS?

A standard expedition lasts about six months. Some crews have stayed roughly a year for research into long-duration flight, and NASA’s Frank Rubio holds the single-mission American record at 371 days, set in 2023 after his ride home was replaced. Rotations overlap by a few days so departing crews can hand over the keys in person.

When will the ISS be retired?

Current plans run to about 2030. After that, a SpaceX-built deorbit vehicle — ordered in 2024 under a contract worth up to $843 million — is to drag the station into the atmosphere for a controlled reentry over the ocean, most debris burning up on the way down. NASA expects commercial stations to take over the orbital-laboratory job afterward.