Voyager Program

The Voyager program sent two robotic probes, Voyager 1 and Voyager 2, on the greatest road trip in history. Launched by NASA in 1977, they toured the giant outer planets and then kept going, becoming the first human-made objects to leave the Sun’s bubble and enter interstellar space.

Quick facts

• Launched: 1977 (Voyager 2 in August, Voyager 1 in September).
• Operator: NASA, managed by the Jet Propulsion Laboratory.
• Power: nuclear batteries called radioisotope thermoelectric generators, which turn the heat of decaying plutonium into electricity.
• Still operating: both spacecraft were still sending data more than 45 years after launch, from over 20 billion km away.
• Famous cargo: each carries a gold-plated Golden Record of sounds and images from Earth.

The grand tour

The mission took advantage of a rare planetary alignment that happens about once every 175 years, letting the probes swing from one giant planet to the next using each world’s gravity as a slingshot. Voyager 1 flew past Jupiter and Saturn, sending back the first close looks at their storms, rings, and moons. Voyager 2 went further, becoming the only spacecraft ever to visit all four giant planets: Jupiter, Saturn, Uranus, and Neptune.

Why it matters

The Voyagers transformed planetary science. They revealed active volcanoes on Jupiter’s moon Io, hints of a hidden ocean on Europa, the thick orange haze of Saturn’s moon Titan, and the tilted, strange worlds of Uranus and Neptune. In 2012 Voyager 1 crossed into interstellar space, and Voyager 2 followed in 2018, giving humanity its first direct measurements of the space between the stars. Carried with them, the Golden Record stands as a message in a bottle, a snapshot of Earth meant to outlast our civilization itself.