A satellite orbiting about Earth does not fall down because of ___________.
the orbital velocity provided to it.
Satellites are able to orbit around the Earth without falling because they are locked into the speed called orbital velocity. Orbital velocity is the speed provided to the satellite in its orbit which provides the centripetal force sufficient enough to keep it in the orbit.
Satellites are sent into space by a rocket launched from the ground with enough energy to get outside our atmosphere. Once the rocket reaches its specified location it drops the satellite into its orbit with the orbital velocity.