International Space Station

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International Space Station

The international space station is the largest and most expensive space vehicle to date. It orbits at an altitude of 280-460 km, going around the world every 92 minutes, so there are sixteen sunrises and sunsets per day on the station. The windows of the space station are shuttered during the sleeping period when the astronauts fasten themselves to their beds. Energy is provided by solar cells that track the Sun (and by batteries when it is in the shade) and oxygen is produced from the electrolysis of water (requiring 1 litre of water per person per day). Drinking water is processed from the water vapour breathed out by the astronauts and from their urine. The crew’s food comes in tins and plastic bags, and waste is taken back to Earth by supply vessels.