Unlike Voyager and Pioneer the next space craft to leave the solar system, New Horizons, is not carrying a message from planet Earth. That can still be fixed. Onboard of New Horizons there is a computer that can be used to store a message when mission is completed beyond Pluto. What will the message be? How will possible aliens hack into the New Horizons computer to find the message? I’m curious to learn more about this project.
To learn more about the earlier probes leaving our Solar system you can check out the links in my post about the Voyager Golden Records.
Project web site: New Horizons Message
The Planetary Society: New Horizons One Earth Message
Space.com: NASA Pluto Probe May Carry Message to Aliens