International Space Station
Space station · Human-made
The International Space Station is the biggest thing humans have ever built in space – a laboratory and home where astronauts from many countries live and work. People have been living on board without a break since November 2000.
- About 400 km upA car would get there in about 4 hours – if it could drive straight up!
- ~28,000 km/hSpeed
- ~90 minutesOne orbit
Take a closer look
Falling all the time
At the height of the ISS, gravity is still about 90% as strong as on the ground. Astronauts float because the station and everyone inside it are falling around Earth together, moving sideways so fast that they keep missing the ground. Sleeping means zipping into a sleeping bag tied to the wall.
Recycling every drop
Water is too heavy to keep sending up by rocket, so the station recycles it. Machines collect moisture from the air, sweat and even urine, and clean it into fresh drinking water – about 98% of it is reused. As astronauts like to say, today’s coffee is tomorrow’s coffee.
Staying strong in space
Without gravity pulling on them, muscles and bones grow weaker, a bit like a leg in a plaster cast. So astronauts exercise for about two hours every day, strapped to a treadmill, a bike and a special weight machine. Studying their bodies helps doctors on Earth understand ageing and bone loss.
How we found out
- 1998
The first piece, the Russian module Zarya, is launched. Over the next years, dozens of pieces are added like building blocks.
- 2000
The first crew moves in on 2 November. There have been people in space ever since.
- 2011
The main assembly is finished, after more than 30 Space Shuttle missions helped build it.
- 2020
SpaceX’s Crew Dragon becomes the first privately built spacecraft to carry astronauts to the station.
- ~2030
The station is planned to be retired and steered down to burn up over a remote part of the Pacific Ocean.
Why can you only see the ISS shortly after sunset or before sunrise?
The ISS doesn’t make its own light – it reflects sunlight. You need a dark sky where you are, while the station high above is still lit by the Sun.
See it yourself
It looks like a very bright, steady star gliding across the sky in a few minutes – no blinking lights like a plane. Check the “next visible pass” times below!
From the encyclopedia
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