Voyager 2 launch — the Grand Tour
Launched on 20 August 1977, Voyager 2 is the only spacecraft to have visited all four giant planets: Jupiter, Saturn, Uranus and Neptune. Its journey used a line-up of the planets that comes around only about once every 176 years.
Available views: Orbit ✓ · Sky — (not visible in the sky)
The story
On 20 August 1977 Voyager 2 left Cape Canaveral on a Titan IIIE-Centaur rocket. At that time Jupiter, Saturn, Uranus and Neptune were lined up in a special arrangement that comes around only about once every 176 years. By passing close to one planet and using its gravity to change speed and direction toward the next, a single spacecraft could visit all four. This journey was called the Grand Tour.
Voyager 2 left sixteen days before its twin, Voyager 1. It is called number 2 because it took the slower route. Voyager 1, launched later on a faster path, reached Jupiter first. Voyager 2 instead took on the longer route past all four planets.
Voyager 2 flew past Jupiter in July 1979 and Saturn in August 1981. Then it became the first spacecraft to see Uranus up close, in January 1986, and Neptune, in August 1989. No other spacecraft has visited Uranus or Neptune since. So nearly all our close-up pictures of those two planets still come from Voyager 2.
After the planets, Voyager 2 kept going, and on 5 November 2018 it entered interstellar space, the region beyond the Sun's bubble of influence. It was the second spacecraft to do so, after Voyager 1. It is still moving away at about 15 km per second toward the southern sky. The orbit view reproduces its twelve-year path past all four planets.
Mission goals
The Grand Tour was possible thanks to gravity assists, which use a planet's gravity to gain speed. Jupiter threw Voyager 2 on toward Saturn, Saturn toward Uranus and Uranus toward Neptune. Without that help, the trip to Neptune would have taken close to thirty years; Voyager 2 did it in twelve. The line-up was first noticed in 1965 by Gary Flandro at NASA's Jet Propulsion Laboratory.
Together, the two Voyagers made the first detailed map of the outer solar system. Io's volcanoes, Europa with a possible ocean under its ice, Titan with its thick atmosphere and Triton with its geysers were all revealed for the first time. Most of the places later explored by Galileo, Cassini, JUICE and Europa Clipper were first shown to us by the Voyagers.
Uranus has had no visitor since 1986, and Neptune none since 1989. That is why the US planetary science community's 2022 ten-year plan ranked a Uranus orbiter as its top large mission. The close-up data Voyager 2 gathered in about a day of passing each planet is still all we have.
Mission chronology and background
The original plan was bigger. NASA had hoped to send several spacecraft on Grand Tours, but budget cuts in the early 1970s reduced this to two, and the official goal only went as far as Jupiter and Saturn. The extension to Uranus and Neptune was approved later. Meanwhile Voyager 1 changed course to take a close look at Saturn's moon Titan, so the four-planet journey fell to Voyager 2.
Voyager 2 has survived many troubles. Its main radio receiver failed in 1978, and since then it has taken commands only through its backup. Because it lies in the southern sky, the only antenna that can send it commands is DSS-43 in Canberra, Australia. While that antenna was being upgraded, from March 2020 to February 2021, sending commands was difficult. In July 2023 a wrong command turned its antenna 2 degrees away from Earth, and contact was lost for about two weeks before it was restored.
Voyager 2 makes its electricity from the heat of plutonium, and the power drops by about 4 watts every year. So the team has been switching instruments off one at a time, including a plasma instrument in 2024 and a particle instrument in 2025. The aim is to keep in touch into the early 2030s. After that, Voyager 2 will drift on silently with its golden record, passing 1.7 light-years from the star Ross 248 in about 40,000 years.
Other milestones of this mission
- Voyager 1 launch
- Voyager 2 at Neptune
- Voyager 1 enters interstellar space
- Voyager 1 passes one light-day from Earth(planned)
Where to see it — sky and simulator
In 2026 Voyager 2 is about 142 AU from the Sun, in the direction of Pavo, the Peacock, in the southern sky. One AU is the distance from Earth to the Sun, so it is 142 times farther away than that. It is far too distant and small for any telescope to see. Even at the speed of light, a signal takes nearly 20 hours to reach it.
The orbit view reproduces, in order, the 1977 launch, the flybys of Jupiter, Saturn, Uranus and Neptune, and the path out of the solar system. Follow the probe and speed up time, and the track can be seen bending at each planet. In the 3-D interstellar view, Voyager 2's current position is marked together with Voyager 1, Pioneer 10 and New Horizons.
See this for yourself — replay the moment in the orbit view
FAQ
Why did Voyager 2 launch before Voyager 1?
Voyager 2 took the slower route, so it left first. Voyager 1, on a faster route, reached Jupiter first and so became number 1.
How did it visit all four planets?
It used a line-up of the planets that happens about once every 176 years, making several gravity assists in which each planet's gravity sent it on toward the next.
Where is it now?
About 142 AU from the Sun in 2026, toward Pavo in the southern sky. It entered interstellar space in 2018.
How long will contact last?
Its power falls every year, and the goal is to stay in contact into the early 2030s. After that it will keep flying without a signal.
Related
Times and figures are approximate — verify with official sources when planning travel. Simulation uses J2000 mean elements.