We could launch 10,000 time capsules into space on trajectories that bring one of them back to Earth every 50,000 years or so. They would have to be designed in

We could launch 10,000 time capsules into space on trajectories that bring one of them back to Earth every 50,000 years or so. They would have to be designed in a way that makes re-entry spectacularly visible so they would be noticed and it would be possible to track them down. Not perfect, but at least there is some chance that one would arrive while an intelligent species is thriving.