How does it work?
A strange insect
Satellites are our eyes, ears and senses to see from above what we cannot do from down here. For the rest, they look rather like strange, high-performance insects.
Full blast, but without a motor!
To resist the attraction that large objects exert on them, satellites, whether natural or artificial, have to move very fast, at least 1 km/second, which is 3,600 km/hour. That’s three times the distance between Paris and Berlin (about 1,100 km) in 60 minutes! But most astonishing is that satellites don’t need a motor to do that; they just let themselves fall indefinitely around their planet. They also need to be given a good kick in the backside to get out of the Earth’s atmosphere and be given their initial acceleration, which is the job of the launchers*. But once that has been done, almost nothing can be done to stop them or slow them down as soon as they reach the void of space.
Standard and optional equipment, just like in a car…
All satellites are made up of two main parts. Firstly there’s a “platform” that ensures the satellite’s proper operation, its position, direction, and its electricity supply; then there’s a “payload”, which is made up of the reason we need it, tools for observation, measurement or telecommunications.
A skeleton for all seasons
The satellite’s structure is ultra-rigid and light, made from aluminium alloy, magnesium, titanium, beryllium, or carbon or Kevlar fibres. The satellite’s “bones” often weigh only 10% of its total weight (as compared with 20% on average for a person). They support the satellite’s various organs, the payloads*, propellant tanks*, batteries, solar panels, antennae etc, which have to stand up to the thousands of particles or debris that wander round space, as well as temperatures ranging from +200o to –150o Celsius.
The absolute need for no breakdowns
Unlike a car, you cannot take the satellite to a garage. And going to repair it, using a shuttle for example, would cost much more than sending a new one! So a satellite must be extremely reliable. That’s the reason why all its most vital components are duplicated, in case the first ones break down.
