what allows satellites to stay in
space
A satellite turns around a celestial body with a speed such as the centrifugal force compensates for its weight. He
is thus pseudo-isolated, why his speed remains constant. Contrary to a wide-spread idea, the satellite is not in
weightlessness. He even permanently is falling, but, thanks to his speed, he falls "close by" of the Earth. Without the
friction of the air, we could put into orbit at any height, by thinking all the same of avoiding the obstacles. But the
atmosphere prevents from placing a satellite unless 200km of height. And still there is a little of air in this corner, so
well the satellite placed also low will hold only a few days: slowed down by the air, he will fall again inevitably into
the atmosphere and will waste away there.
CHARACTERISTICS OF THE ORBIT:
The orbit of a satellite will be circular only if its injection is made, on one hand in a parallel to the earth, and on the
other hand at the good height for a given speed. If these conditions are not respected, the orbit is elliptic.
If the speed is lower than the parabolic speed but superior to the circular speed, the satellite will describe an elliptic
orbit between the satellite dish and the circle. If the point of injection is parallel to the ground horizon, he will
determine his périgée, the closest to the earth.
If the speed is lower than the circular speed at the given height, the satellite travels an elliptic orbit the point of
injection of which is the peak, the highest. The satellite according to the height and the speed can meet the earth on
its path.