NASA · Interstellar mission
The most distant object humans have ever built. On November 18, 2026, its radio signal will need a full day to reach Earth for the first time.
· Cape Canaveral
In the late 1970s the outer planets lined up so that a spacecraft could hop from one to the next, picking up speed from each planet's gravity. That arrangement comes around roughly once every 175 years.
NASA sent two identical probes. Voyager 1 launched 16 days after its twin, on a faster path, and overtook it in December 1977.
Inside the spacecraft
All the onboard computers together hold about 70 kilobytes of memory. Power comes from three radioisotope generators that turn the heat of decaying plutonium-238 into electricity with no moving parts.
Long booms keep sensitive instruments away from the spacecraft's own electronics.
· Jupiter
The probe passed 349,000 kilometers from Jupiter's center. A few days later, navigation engineer Linda Morabito spotted a bright plume rising over the edge of the moon Io in one of the images. It was the first active volcano ever found beyond Earth.
Voyager 1 also discovered Jupiter's thin ring.
· Saturn
The team could have sent the probe on to Pluto. They chose a close pass of Titan, Saturn's largest moon, instead. Under its orange haze was a thick nitrogen atmosphere.
The maneuver bent Voyager 1's path up and out of the plane where the planets orbit. It never met another planet.
On board · A message
A gold-plated copper disc 30 centimeters across. It holds 115 images, greetings in 55 languages, sounds of Earth and about 90 minutes of music, from Bach to Chuck Berry.
The cover is engraved with instructions for playing it and a map of 14 pulsars that points the way to the Sun.
· 6 billion km
At astronomer Carl Sagan's request, the probe turned its cameras back toward home and took 60 frames for a "family portrait" of the solar system. In one of them Earth fills 0.12 of a pixel, caught in a ray of scattered sunlight.
Soon after, the cameras were switched off for good to save power for the long road ahead.
· 121 AU
The Sun sits inside a bubble blown by its own wind, a stream of charged particles. About 18 billion kilometers out, that stream runs into the gas between the stars.
Voyager 1 crossed this boundary, the heliopause, and became the first spacecraft in interstellar space. Confirmation came in 2013, when its plasma wave instrument picked up the vibrations of dense interstellar plasma.
· 25.9 billion km
From this day on, a radio wave sent to the probe in the morning reaches it the next morning. Engineers see the reply to any command two days after they send it.
The generators lose about 4 watts of power a year. To stretch what is left, the team is switching science instruments off one by one. They hope to keep in contact into the early 2030s.
In 40,000 years
By then the probe will have long gone silent. The record with Earth's voices and music will keep flying.
Facts: NASA/JPL. The spacecraft, planets and sky are built procedurally in three.js and are not exact models. Distance from Earth is approximate, extrapolated from the light-day crossing date.