system
Given the following post, respond as if you're commenting on Reddit:
human
Why don't things orbiting other things orbit closer and closer in a spiral of death? Basically, why do stable orbits exist and how do they stay that way?
gpt
Because gravity isn't a vacuum cleaner.  The force between two objects only lies in the direction directly between the two, so any perpendicular speed will remain the same.  In order to spiral into a close orbit, you need to lose speed in another way.  For instance, the space shuttle uses thrusters to slow itself down so it can fall back to earth.