The Pioneer and Voyager Flybys — The First Spacecraft to Visit Saturn

Their names were Pioneer 11, Voyager 1, and Voyager 2. They were launched in the 1970s, when astronauts had only just walked on the Moon and computers were the size of a room.

Each of them flew past Saturn just once — close enough to take photographs, measure the rings, study the moons — and then sailed on into the empty space beyond, never to return. Between 1979 and 1981, these three spacecraft transformed Saturn from a distant point of light in a telescope into a real, photographed place.

And, remarkably, two of them are still working today, almost 50 years after they left home.

This is the story of the three missions that opened up Saturn.

Quick Pioneer and Voyager facts

A pocket-sized comparison of the three flyby missions.

Why early spacecraft just flew past

These three missions were called flybys — they flew past Saturn without slowing down to stop. Compare that to Cassini, which arrived at Saturn in 2004 and stayed in orbit for thirteen years before its mission ended. Why didn't Pioneer or Voyager do the same? The answer comes down to fuel and speed.

To put a spacecraft into orbit around Saturn, it has to slow down enough that Saturn's gravity can capture it. That takes an enormous amount of fuel — fuel that has to be carried all the way from Earth.

In the 1970s, the technology to send a heavy enough spacecraft to Saturn, with enough fuel left over to slow down on arrival, didn't quite exist yet. Cassini, when it finally did this in 2004, was one of the most ambitious spacecraft ever built.

The Pioneer and Voyager spacecraft were much smaller and simpler. They had just enough power to fly straight past Saturn, take measurements as they went, and continue on into deep space.

That meant each one had only one shot. A few hours of close-range observation, a few days of useful data, then the planet was already shrinking behind them and the mission moved on. The teams back on Earth had to plan every minute of those encounters perfectly. They got it right.

Pioneer 11 — the first spacecraft ever to reach Saturn

Pioneer 11 was launched on 6 April 1973 from Cape Canaveral in Florida. Its first job was to visit Jupiter, which it did in December 1974.

Then, instead of heading out of the solar system the way its sister craft Pioneer 10 did, Pioneer 11 used Jupiter's gravity as a slingshot to bend its path toward Saturn. Five more years of empty space later, on 1 September 1979, Pioneer 11 became the first spacecraft from Earth ever to fly close to Saturn.

It went in at speed — about 114,000 km per hour — and passed within just 21,000 km of Saturn's cloud tops. That's only twice the diameter of Earth away.

It was the closest approach to Saturn anyone had ever made, and nothing has flown that close to Saturn from outside since (Cassini orbited at a safer distance most of the time). Over those few hours, Pioneer 11 took 440 photographs of Saturn and its moons, measured Saturn's magnetic field for the first time, and discovered something important: a thin, bright outer ring that no one had seen from Earth.

We now call it the F ring.

Pioneer 11 also discovered two small moons (or confirmed objects that had been only loosely seen before), and took the first close-range pictures of Saturn's larger known moons — including the orange fuzz of Titan, which Pioneer's instruments showed was extremely cold but couldn't see through the haze. After the flyby, Pioneer 11 kept going.

It crossed the orbit of Neptune in 1990 and continued outward. NASA received the spacecraft's final engineering data on 24 November 1995 — its tiny power supply had finally faded.

Pioneer 11 is still drifting silently outward today, somewhere beyond the Kuiper Belt.

Voyager 1 — the Titan flyby

Voyager 1 was launched from Cape Canaveral on 5 September 1977 — a few weeks after its twin Voyager 2, but on a faster, shorter trajectory that got it to its targets first. It visited Jupiter in March 1979, then crossed nearly two years of empty space to reach Saturn. Voyager 1's closest approach to Saturn happened on 12 November 1980, when the spacecraft passed about 124,000 km above Saturn's cloud tops.

Voyager 1 had a specific job at Saturn: to take a really good close look at Titan, Saturn's biggest moon. Telescopes from Earth had shown Titan had some kind of atmosphere, but nobody knew much about it.

Was it thick or thin? Was it nitrogen, methane, something else?

Was there liquid on the surface? Voyager 1's flight path was designed to bring it close to Titan, even though that meant the spacecraft would be pushed up out of the flat plane of the solar system afterward — losing any chance to visit Uranus or Neptune later.

Voyager 1 found that Titan's atmosphere is thick — thicker than Earth's — and made almost entirely of nitrogen. That single result instantly turned Titan from a mystery into one of the most interesting moons in the solar system.

Voyager 1 also discovered three more new moons of Saturn, photographed Saturn's rings in extraordinary detail, and noticed mysterious dark 'spokes' streaking across Saturn's B ring — patterns nobody had expected and that scientists still don't fully understand. After the flyby, Voyager 1's path bent upward and out of the plane of the planets, on a long slow trajectory toward interstellar space.

Visit Titan, Saturn's biggest moon — to see what Voyager 1's discovery led to over the decades that followed.

Voyager 2 — and the Grand Tour

Voyager 2 was launched on 20 August 1977 — earlier than Voyager 1 — but onto a slower, more curving trajectory that took it past Jupiter (July 1979) and then on to Saturn. It made its closest approach to Saturn on 25 August 1981, passing about 101,000 km from the cloud tops.

Voyager 2's plan was different from Voyager 1's. Engineers had noticed something remarkable: in the late 1970s, the four giant outer planets — Jupiter, Saturn, Uranus and Neptune — were going to line up in a way that happens only once every 175 years.

A single spacecraft, with the right trajectory, could use the gravity of each planet to slingshot to the next, visiting all four in just over a decade. They called it the Grand Tour.

Voyager 2 was the spacecraft that would attempt it.

For that to work, Voyager 2 couldn't take the close-Titan path Voyager 1 had taken. Instead, it had to fly past Saturn in just the right place so that Saturn's gravity would bend its path onward to Uranus.

The mission worked. Voyager 2 visited Uranus in January 1986, and Neptune in August 1989 — the first and (so far) only spacecraft ever to visit those two planets up close.

None of that would have been possible without the Saturn flyby being aimed exactly right.

At Saturn itself, Voyager 2 photographed the half-young, half-old surface of Enceladus (the small moon scientists would later realise has geysers), tracked individual storms in Saturn's atmosphere for the first time, and took the photographs that — six years later — astronomer David Godfrey would piece together to reveal Saturn's giant hexagonal jet stream at the north pole.

Explore Saturn's giant six-sided jet stream at the north pole — the feature the Voyagers first photographed without realising it.

Three spacecraft, three jobs — at a glance

How the three flybys compare side by side.

The Golden Record — a message from Earth

Each Voyager spacecraft carries something unusual bolted to its side: a gold-plated phonograph record, about 30 centimetres across, called the Golden Record. The records were the idea of a small team led by the American astronomer Carl Sagan, who wanted both Voyagers — which would eventually drift out beyond the solar system and never come back — to carry a message from Earth, in case any intelligent life ever found them.

Each Golden Record contains greetings spoken in 55 different languages, 27 pieces of music from around the world (from Bach to Chuck Berry to Indian classical music), recordings of natural sounds (wind, rain, whales, a baby crying), and 116 encoded images showing landscapes, animals, people, mathematics, and the Solar System. There is also a sketch on the record's cover explaining how to play it back, using a stylus that was attached to the record itself.

Nobody really expects aliens to find a Voyager spacecraft — the galaxy is too big, and the Voyagers will drift for billions of years without coming close to any star. But the Golden Records exist for another reason: they say something about us.

When we sent something out to explore our solar system in 1977, we also chose to send a portrait of who we were. The Records will outlast Earth itself.

Where the spacecraft are today

All three of these spacecraft are still travelling outward — and the two Voyagers are still alive in 2026.

• Pioneer 11 went silent on 24 November 1995, when its tiny radioactive power source finally faded. The spacecraft is still drifting outward but it no longer transmits. It crossed Neptune's orbit in 1990. It will pass near the star Lambda Aquilae in about 4 million years.
• Voyager 1 is now in interstellar space — the space between stars — having crossed out of the Sun's protective bubble of magnetic field in August 2012. As of May 2026 it is more than 24 billion km from Earth. Its radio signals now take about 22 hours to reach us, one way. NASA's Deep Space Network can still hear it.
• Voyager 2 is also in interstellar space, having crossed the boundary in November 2018. It is slightly closer to Earth than Voyager 1, since it took a longer, more winding path. NASA still receives data from it too.

Both Voyagers are running low on power. Each year, engineers turn off another instrument to save energy. They are expected to keep transmitting basic signals until the early 2030s — by which time they will have been flying for over 55 years. They are humanity's most distant working spacecraft.

The Pioneer-and-Voyager timeline at a glance

Half a century of mission history, in one place.

The handoff to Cassini — 23 years later

After Voyager 2's flyby in August 1981, Saturn went unvisited for 23 years. The Voyagers had found rings, moons, atmospheric storms, and the first hints of the hexagon.

They had photographed Titan's hazy orange ball. They had even taken the pictures that would later reveal the hexagonal jet stream.

But there were limits to what a flyby — a few hours of close-range work followed by years of empty space — could achieve. Scientists wanted to go back, slow down, and stay.

It took two more decades of engineering, planning, and international cooperation before that became possible. When the Cassini-Huygens mission finally arrived at Saturn on 1 July 2004 and slowed itself into orbit, it carried instruments hundreds of times more sensitive than the Voyagers' — and it stayed for 13 years. Every Cassini discovery, from Enceladus's geysers to Titan's lakes to the precise mapping of the hexagon, built directly on what the Pioneer and Voyager flybys had hinted at.

Explore the Cassini-Huygens mission that came next — and the 13 years of discoveries it added to what Pioneer and Voyager began.

Why the flybys still matter

It would be easy, looking back, to say the Pioneer and Voyager flybys were just rough first sketches — and that Cassini, with its better cameras and 13-year stay, did the real work. That isn't right.

The flybys did the impossible-first part. They proved that a spacecraft from Earth could survive crossing the asteroid belt, pass through Saturn's rings safely, take useful photographs in the cold and dark, and send the data home across more than a billion kilometres of empty space.

Without that proof, no one would have built Cassini.

And the discoveries those three quick visits made — the F and G rings, the hexagon's first photographs, Titan's nitrogen atmosphere, the spokes in the B ring, six new moons, Saturn's magnetic field, the first geological maps of Mimas, Enceladus, Tethys, Dione, and Rhea — they shaped every Saturn mission that came after. Pioneer 11, Voyager 1, and Voyager 2 are the reason every kid today can know that Saturn is real, that its rings have structure, that its moons are worlds, and that there is more out there to find. Three small spacecraft, flying past once, and changing everything.

Pioneer and Voyager at Saturn — frequently asked questions

Quick answers to the most common questions.

Mini quiz — test your Pioneer and Voyager knowledge

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Sources and last updated

This page is fact-checked against current sources from NASA and peer-reviewed mission archives.

Last updated: May 2026. All mission dates (Pioneer 11 launch 6 April 1973, Saturn flyby 1 September 1979; Voyager 1 launch 5 September 1977, Saturn closest approach 12 November 1980; Voyager 2 launch 20 August 1977, Saturn closest approach 25 August 1981), closest-approach distances, and Voyager interstellar status (both still operating in 2026) verified against NASA mission archives. Pioneer 11's final signal date (24 November 1995) verified against NASA Ames Research Center records.

Written and fact-checked by the Planets for Kids editorial team.