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Comparison solar arrays
ESA's ATV next to Progress and Apollo

All shapes and sizes

A spacecraft is a machine designed to be put into space. They can be used for observing the Earth, communication, navigation and space exploration. There are also spacecraft that carry humans into space, called 'manned spacecraft', and others that carry the supplies needed to space stations.

Since there is no air in space, a spacecraft can be more or less any shape. Size is more of a problem. A spacecraft must be able to fit inside a rocket fairing and the rocket must have enough power to lift it into orbit.The world’s first satellite, called Sputnik, weighed 83.6 kg and was no bigger than a basketball. Today, communication satellites can weigh more than 6 tonnes (6000 kg).

Modules used to build space stations are even bigger. ESA’s 20 tonne ATV (Automated Transfer Vehicle) can carry up to 9 tonnes of cargo and experiments to the International Space Station.

The shape of a spacecraft mostly depends on whether they spin or not in space.
Some satellites, such as Meteosat, spin and are drum-shaped. Most satellites today are box-shaped and do not spin. Their onboard instruments, such as cameras, face in the same direction most of the time.

Some carry large solar 'wings' (solar panels that transform sunlight into electricity) that turn so they always point toward the Sun. Small satellites often have flat solar panels on four sides.

Landers are different. They have to withstand extreme heat as they descend through the air at high speed. For example, ESA’s Huygens probe, which landed on Titan, was shaped like a saucer, with a forward-facing heat shield.
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