cannon

Newton's cannonball was a thought experiment Isaac Newton used to hypothesize that the force of gravity was universal...

https://en.wikipedia.org/wiki/Newton%27s_cannonball

The cannon fires a ball that falls to earth. The cannon adds some power to the next shot and the cannonball goes a bit farther. Eventually the ball flies with enough velocity to break the planets gravity and falls into orbit. The ball literally falls around the planet indefinitely.