Spacecraft in the Solar System

Something that has truly always interested me is the question of what happens to spacecraft after they are done with their mission. Obviously they float through space but who knows what really happens to each individual craft? Is there a rover that was once patrolling Mars that has made it past Pluto? It’s fascinating that although we understand a lot about space, especially when compared to 100 years ago, but still are relatively clueless about the world we live in. This all reminds me of a Star Trek movie I watched a while ago where the enemy alien species bowed down to a god named “Veeger,” which was really a Voyager probe that had had some letters scratched off.