The twin Voyager spacecraft, launched in 1977, gave us humanity’s first close-up views of Jupiter, Saturn, Uranus, and Neptune. Beyond that, they entered interstellar space, sending back data about cosmic radiation and magnetic fields that no other spacecraft has ever recorded. Scientists see these discoveries as unfinished business. A new Voyager, often imagined as “Voyager 3,” would build on that foundation and continue exploring the cosmic frontier.