Built in the 1970s and now over 13 billion miles from Earth, Voyager 2 runs on a tape recorder holding just 64 megabytes yet remains the only object to visit Uranus and Neptune. This episode tells the story of a spacecraft that launched as a backup and became our greatest interplanetary explorer, still sending data from interstellar space in 2026.

We explain the rare planetary alignment behind the Grand Tour, why Voyager 2 launched before Voyager 1, and the hydrazine thrusters and plutonium-powered RTGs that keep it alive. We walk through its discoveries, from active volcanoes on Io and a smooth ocean-hiding Europa, to the jammed scan platform at Saturn that engineers fixed with heat, an accident that locked in the trajectory to the ice giants.

• The sideways planet Uranus and a plasmoid found in old data in 2020
• The needle ...