Explain how the force due to gravity keeps a satellite in orbit

Once a satellite is launched into orbit, the force of gravity tends to pull it toward the Earth. But by moving fast enough, it falls in a curved path and circles the Earth. So orbit is something like a controlled fall. If a satellite lite does not move fast enough, it will eventually spiral closer to the Earth and burn up in the Earth's atmosphere. The same balance of gravity and speed keeps the moon and the International Space Station in orbit.