Escape Velocity
In physics, escape velocity is the speed where the kinetic energy of an object is equal in magnitude to its potential energy in a gravitational field. It is commonly described as the speed needed to "break free" from a gravitational field. On the surface of the Earth, the escape velocity is about 11.2 kilometers per second
How are satellites launched?
Most satellites are sent into orbit either on rockets or expendable launch vehicles, which fall into the ocean once they've used up all their fuel. Some, such as the Hubble Space Telescope, are launched via the USA's Space Shuttle which returns to Earth after each mission and is reused. The trick when launching a satellite is to get it high enough to do its job without losing the capsule to outer space. It's a delicate balance of push and pull, accomplished by the inertia of the moving object and the Earth's gravity. If you launch a satellite at 17,000 mph, the forward momentum will balance gravity, and it will circle the earth. On the other hand, if the satellite is launched faster then 23,500 mph, it will leave the gravitational pull of the Earth.