What is a satellite?
Watch out for the drop!
In point of fact, a satellite never stops falling but never crashes…now that’s smart! To carry that off, we have to understand that it is not falling onto Earth but round it. Explanations…
Why does it stay up all by itself?
If we think of the Moon as a tennis ball, why doesn’t it drop to earth, like the apple on Newton’s head? Because when it was created the Moon received a very strong push that let it partially escape Earth’s pull*. It is that mix of the push and Earth’s pull that make the Moon never stop falling, though not onto earth but round it: it is in orbit*. Exactly the same thing happens with an artificial satellite.
And if we carried out an experiment?
Take our tennis ball and throw it as hard as possible in front of you. The harder you throw it the further it will go before dropping to the ground. If you had some sort of magic gift, you would manage to throw it so hard that its curve as it fell would be exactly parallel with the curvature of the earth, which is round. So your ball would never stop falling but without ever touching Earth. It would become a satellite, that is it would be in orbit around the earth. Funny way to play tennis…
One thing’s certain, it will need a catapult!
To send very heavy objects out of earth’s atmosphere (satellites weigh at least a ton, and can sometimes weigh up to 15 tons), it takes a great deal of energy from the launchers*, which are often called rockets. Once the launcher will have brought the satellite to outside the atmosphere* (from 220 km above the Earth), it can put it into its orbit, which is its trajectory.
Les fiches
Sur le même thème
Preparing for take off
Communication satellites- Can a satellite be driven
- Question of orbit
- Launch OK but where
Dreaming the impossible
The ATV or automated transfer vehicule- Astrophysicist : Space industry carreers
