47 Fun Facts About Voyager Missions

Which president's message rides aboard Voyager's Golden Record?

Jimmy Carter called the record "a present from a small distant world" and wrote that humanity was attempting to survive its time so that it might live into the finder's.

Voyager 1 launched 16 days after its twin but overtook Voyager 2 while both were crossing what?

The asteroid belt is where Voyager 1 pulled ahead in December 1977; its shorter, faster route then delivered it to Jupiter four months before the probe that had left Earth first.

From which US launch site did both Voyager probes lift off in 1977?

Cape Canaveral launched the pair in reverse order: Voyager 2 lifted off first, on August 20, and Voyager 1 followed from the same pad on September 5.

Which rocket launched the Voyager probes?

Titan IIIE existed because NASA's Atlas-Centaur was too weak to throw heavy probes such as Viking and Voyager at the planets, so the Centaur upper stage was moved onto a far bigger booster.

When Voyager 1's booster shut down early, its Centaur stage saved the launch with roughly how much fuel to spare?

About 3 seconds' worth was left in the tanks: the Centaur had to burn longer than planned to cover for the stage below it, while the launch team waited to hear whether it would be enough.

What rare event, spotted by Gary Flandro, made Voyager's Grand Tour possible?

A planetary alignment that recurs only about every 175 years let one craft slingshot from world to world; Flandro found it by graphing where each planet would be, cutting roughly two decades off the trip to Neptune.

Why was the original Grand Tour mission cancelled in December 1971?

Funding went to the Space Shuttle because President Nixon would not pay for both at once, so NASA's chief swapped the Grand Tour for two cheaper probes bound only for Jupiter and Saturn: the future Voyagers.

What were the Voyagers originally going to be called?

Mariner 11 and 12 were the names until March 1977, months before launch, when NASA decided the craft had outgrown the Mariner family and ran a contest that produced Voyager.

Which Chuck Berry hit travels on the Voyager Golden Record?

Johnny B. Goode drew the objection that rock music was adolescent; the reply that kept it on the record was "There are a lot of adolescents on the planet."

Which moon did Voyager 1 study instead of continuing to Pluto?

Titan's thick atmosphere made it a prime target, and the close pass flung Voyager 1 up out of the plane of the planets, so no further encounters were possible.

What did Voyager 1 discover on Jupiter's moon Io?

Active volcanoes on Io were the first seen anywhere beyond Earth; the heat comes from a gravitational tug-of-war between Jupiter and its neighbouring moons that keeps flexing Io's interior.

Voyager measurements confirmed which of these as the largest moon in the Solar System?

Ganymede is even bigger than the planet Mercury, and Voyager's close-ups showed its icy crust split between old cratered ground and younger grooved terrain, a sign the whole shell had once been stretched.

Which moon of Jupiter did a Voyager scientist say had lines that "might have been painted on with a felt marker"?

Europa's lines proved almost perfectly flat in Voyager 2's sharper images, which deepened the puzzle; the leading explanation is a thin crust of ice floating on an ocean.

Which moon of Saturn did Voyager 1 show scarred by a giant crater, making it look like the Death Star?

Mimas carries Herschel, a crater a third as wide as the moon itself; the impact that dug it probably came close to breaking Mimas apart.

What was applied to some Voyager cables shortly before launch to improve radiation shielding?

Kitchen-grade aluminium foil was a last-minute extra: an earlier probe had found Jupiter's radiation far fiercer than expected, and the foil gave exposed cables one more layer of protection.

Voyager 1 found Saturn's upper atmosphere short of which gas, a hint that it is slowly sinking into the planet?

Helium made up only about 7 percent of Saturn's upper air against 11 percent at Jupiter; if the heavier gas is sinking through the hydrogen, that could explain why Saturn gives off more heat than it gets from the Sun.

Roughly how fast are the winds the Voyagers clocked near Saturn's equator?

About 1,800 km/h, or 1,100 mph: the winds blow mostly eastward, which told scientists they are not just skimming the cloud tops but reach at least 2,000 km down into the planet.

In 2017, which long-idle part of Voyager 1 worked perfectly after 37 years without use?

Its backup thrusters, dormant since 1980, took over from worn attitude jets so the antenna could stay pointed at Earth, which bought the mission another two to three years.

Which disaster struck four days after Voyager 2's Uranus flyby?

Challenger broke apart on January 28, 1986, while Voyager 2's Uranus results were still coming in; the loss also kept the Galileo probe, due to leave for Jupiter that May, on the ground until 1989.

Voyager 2 found that Uranus's sideways spin pulls the tail of its magnetic field into what shape?

A long corkscrew trails behind Uranus because its magnetic field is tilted about 60 degrees from the axis the planet spins on; nobody had measured that field at all before Voyager 2 arrived.

Voyager 2 found which moon of Uranus cut by huge fault canyons, as if it had been shattered and reassembled?

Miranda's canyons run up to 12 times as deep as the Grand Canyon, and its patchwork look inspired the theory of a moon blown apart and reassembled, though scientists still disagree about what really shaped it.

What did Voyager 2 discover in Neptune's atmosphere in 1989?

The Great Dark Spot was a storm about as wide as Earth, yet when Hubble looked for it in 1994 it had vanished: Neptune's giant storms come and go, while Jupiter's Red Spot has lasted for centuries.

Hours after skimming Neptune's north pole in 1989, Voyager 2 made its last close flyby, of which moon?

Triton proved to be the coldest world then measured, about 38 kelvins, yet Voyager 2 still caught geysers there shooting dark plumes several kilometres high.

Astronomers had glimpsed only broken 'ring arcs' at Neptune; what did Voyager 2 show them to be?

Parts of complete rings: most of the material is so thin and fine that from Earth only the clumpiest stretches of the outer ring had shown up, looking like disconnected arcs.

What jammed on Voyager 2 just after it passed Saturn in 1981, costing it some planned observations?

Its camera platform, a swivelling mount for the cameras and spectrometers, froze as Voyager 2 left Saturn; commands from Earth later got it moving again, in good time for Uranus.

Since a 1978 failure, what must engineers do so Voyager 2's damaged radio receiver can hear a command?

Tune it very precisely: the main receiver died, and a failed capacitor left the backup able to pick up only one narrow frequency, so each transmission must allow for Earth's motion and even the receiver's temperature.

How wide is each Voyager's main dish antenna?

About 3.7 metres: even with a dish that size, distance has throttled the link from roughly 115,000 bits per second at Jupiter to about 160 by the 2020s.

What powers the Voyager spacecraft?

Plutonium-238 generators turn the heat of radioactive decay into electricity because sunlight is far too weak out there for solar panels: at Neptune it is about 900 times dimmer than on Earth.

The Golden Record's cover carries a map showing where the Sun lies; which objects does it use as landmarks?

Pulsars each flash at their own steady rate, so the map fixes the Sun's position relative to 14 of them and gives every one's precise pulse period as a fingerprint.

Which Australian radio telescope, a prime receiver of Apollo 11's moonwalk pictures, was linked in to hear Voyager 2 at Neptune?

Parkes was tied by microwave link to NASA's Canberra antennas so the two sites worked as one giant ear, while in New Mexico the 27 dishes of the Very Large Array were yoked to Goldstone in the same way.

Which bright moon of Saturn, later found to spout geysers, did the Voyagers show to have smooth, young-looking plains?

Enceladus is the most reflective body in the Solar System, and the smooth stretches Voyager saw were the first hint of a restless interior; in 2005 Cassini caught icy jets erupting from its south pole.

Why can only a dish near Canberra, Australia, send commands to Voyager 2?

The probe is far south because its 1989 pass over Neptune's pole bent its path steeply below the plane of the planets, hiding it from the big northern dishes in California and Spain.

In August 2012, Voyager 1 became the first human-made object to enter what?

Interstellar space began for Voyager 1 in August 2012, but NASA needed a year to be sure: its plasma sensor had long since died, so proof came when a solar outburst made the gas around it ring like a violin string.

In 2023 a mistaken command cut contact with Voyager 2 for two weeks by doing what?

Tilting its antenna away from Earth by just 2 degrees was enough; NASA won contact back with a high-power "shout" from its Canberra dish, telling the probe to turn its ear toward home again.

Voyager 1 crossed which boundary in 2004, where the solar wind abruptly slows below the speed of sound?

Termination shock is where the Sun's supersonic wind runs into the pressure of the gas and magnetic field between the stars and brakes hard; Voyager 1 met it about 94 times farther from the Sun than Earth is.

What did Voyager 2 hitting the shock boundary closer to the Sun reveal?

The southern hemisphere of the heliosphere is being pushed in by the interstellar magnetic field.

What did Voyager data reveal the heliosheath to be filled with in 2011?

Giant magnetic bubbles form where the Sun's distant field lines crowd together, break and reconnect; the find replaced the old picture of a smooth, streamlined frontier with a frothy one.

What is the photograph of Earth that Voyager 1 took on February 14, 1990, called?

Pale Blue Dot shows Earth as a speck barely a pixel wide; the sunbeam it seems to float in is stray light bouncing around inside the camera, which was looking back toward the Sun from 6 billion km away.

What happened to Voyager 1's cameras after the 1990 Family Portrait?

They were switched off to save power and memory for instruments studying the space beyond the planets; the camera software has since been deleted, and the computers on Earth that could read the pictures no longer exist.

Who chaired the committee that chose the contents of the Voyager Golden Record?

Carl Sagan called the record a bottle launched into the cosmic ocean: it would be played only if spacefaring civilisations exist, he said, but sending it "says something very hopeful about life on this planet."

What caused Voyager 1 to stop sending readable data in November 2023?

A bad memory chip had taken part of one computer's code with it; unable to repair it, engineers cut the lost code into sections and tucked them into spare corners of memory, and readable data returned in April 2024.

Roughly how long does a radio command take to reach Voyager 1 and its reply to return, as of 2025?

About 2 days: in 2024 a signal needed some 22.5 hours each way, so engineers who radioed up a fix had to wait the best part of two days to learn whether it had worked.

What Guinness World Record does the Computer Command System aboard Voyager 2 hold?

Longest continual operation for a computer: the command system has run without a break since launch day in August 1977, even while engineers on Earth kept radioing up new software for it.

How long until Voyager 1 drifts close to another star?

About 40,000 years: around the year 40,272 Voyager 1 should pass within two light-years of an obscure star in the northern sky, long after its power has run out and its radio has fallen silent.

What name did scientists give the dark streaks the Voyagers saw forming and fading across Saturn's B ring?

Spokes are thought to be clouds of fine dust lifted above the ring by static charge; they startled scientists because gravity alone, which shapes the rest of the rings, cannot explain them.

Which probe did Voyager 1 overtake in February 1998 to become the most distant human-made object?

Pioneer 10 had held the distance record until then; nothing launched since will catch Voyager 1, because even New Horizons, which left Earth faster, is now the slower craft after Voyager's boost from Saturn.

What did each Voyager carry to store bursts of science data until they could be sent to Earth?

A magnetic tape recorder held readings gathered faster than the radio link could carry them, then played them back when one of Earth's biggest dishes was listening; on Voyager 1 that came round about every six months.