Answer:
Gravity
Explanation:
When its altitude is matched by the pull of the Earth's gravity, a satellite circles Earth. The satellite will fly off into orbit in a straight line or crash down to Earth without this equilibrium.
By juggling two things, a satellite retains its orbit: its velocity (the speed it takes to travel along a straight line) and the gravitational force on it that the Planet provides. To resist the greater gravitational force, a spacecraft orbiting closer to the Earth needs more velocity.
