50 Fun Facts About Voyager Missions

In which year were both Voyager probes launched?

They took advantage of a rare alignment that let one craft reach all the outer planets with gravity assists.

Which probe was launched first?

Voyager 1 followed 16 days later on a shorter, faster path and still reached Jupiter first.

On what date was Voyager 1 launched?

It lifted off from Launch Complex 41 at Cape Canaveral aboard a Titan IIIE.

Which rocket launched the Voyager probes?

A Centaur upper stage rode on top and had to burn far longer than planned to rescue Voyager 1's launch.

How close to running dry was the Centaur stage when it saved Voyager 1's launch?

The Titan's second stage shut down early and left 540 kg of fuel unburned; the Centaur made up the difference.

Which JPL engineer identified the once-in-175-years alignment behind the Grand Tour in 1964?

The Grand Tour itself was cancelled in 1971 when money went to the Space Shuttle.

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

A scaled-down two-spacecraft, four-planet version was proposed the next year.

What were the Voyagers originally going to be called?

The name Voyager was picked in a 1977 competition, echoing William Pickering's earlier suggestion of "Navigator".

What name had William Pickering earlier proposed that the 1977 rename echoed?

Because the change came so close to launch, the probes were still sometimes called Mariner 11 and 12.

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

Its dense atmosphere made it the priority; the flyby threw Voyager 1 out of the ecliptic and ended its planetary mission.

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

It was the first time active volcanism had been seen anywhere beyond Earth.

How many Io volcano eruptions did the two Voyagers observe between them?

Voyager 2 ran a 10-hour "volcano watch" and saw how Io's surface had changed in four months.

Which Jovian moon's lines looked as if "painted on with a felt marker"?

High-resolution Voyager 2 images showed the lines had no relief; a thin ice crust over an ocean is the leading explanation.

Which was the first of Jupiter's moons to be identified by a spacecraft?

Voyager 1 spotted it just outside Jupiter's ring, then found Thebe between Amalthea and Io.

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

Pioneer 10's data had warned engineers just how fierce Jupiter's radiation belts were.

When did Voyager 1 make its closest approach to Jupiter?

It passed about 349,000 km from the planet's centre; most moon and ring observations came in a 48-hour window.

What share of Saturn's upper atmosphere did Voyager 1 find to be helium?

That is less than Jupiter's 11 percent, hinting that helium may be sinking and warming Saturn from within.

How fast were the equatorial winds the Voyagers measured on Saturn?

That is roughly 1,100 mph, far faster than anything on Earth.

Which is the only spacecraft to have visited Uranus and Neptune?

It reached Uranus in 1986 and Neptune in 1989.

In which year did Voyager 2 fly past Uranus?

Closest approach was on January 24, 1986, at 81,500 km above the cloud tops.

How many new moons of Uranus did Voyager 2 discover?

They include Cordelia, Ophelia, Puck and Perdita, most named for Shakespeare characters.

How long is a day on Uranus, as measured by Voyager 2?

The planet's 97.8-degree axial tilt gives it a uniquely odd atmosphere and seasons.

Which Uranian moon showed huge fault canyons, suggesting it was once shattered and reassembled?

One hypothesis is that the moon re-aggregated after being broken apart by a violent impact.

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

Hubble later found the feature had vanished; it may have been a window in the methane cloud deck.

On what date did Voyager 2 make its closest approach to Neptune?

It passed about 4,950 km above Neptune's north pole after a 1987 course correction.

Which of these moons was among the six Voyager 2 confirmed at Neptune?

Despina, Galatea, Larissa, Proteus, Naiad and Thalassa were all confirmed; Triton and Nereid were already known.

What seized up on Voyager 2 after its Saturn flyby?

Worn lubricant, corrosion and a bearing design flaw were blamed; ground commands partly freed it.

What failed on Voyager 2 in 1978, leaving it able to hear only one precise frequency?

A bad capacitor in the backup receiver means Earth must tune commands to the Doppler shift and the receiver's temperature.

What is the diameter of each Voyager's high-gain antenna?

Uplink is on S-band and downlink on X-band, with S-band as backup.

What powers the Voyager spacecraft?

Three RTGs gave about 470 watts at launch, falling roughly 0.79 percent a year.

What is the half-life of the plutonium-238 in the Voyagers' generators?

That means the RTGs lose about 0.79 percent of their thermal output every year.

What was each Voyager's data rate from Jupiter?

It halved by Saturn and has fallen ever since; Voyager 2 now sends about 160 bits per second.

Which Australian radio telescope joined the antenna array for the 1989 Neptune flyby?

The Very Large Array in New Mexico was also pressed into service alongside Goldstone.

The Deep Space Network's main dishes were enlarged between 1982 and 1985 from 64 m to what?

The bigger dishes helped fight the inverse-square fading of the Voyagers' signals.

Which Canberra antenna is the only one that can talk to Voyager 2?

Voyager 2's southward trajectory puts it out of reach of the Goldstone and Madrid complexes.

On what date did Voyager 1 cross the heliopause into interstellar space?

NASA did not confirm the crossing until September 2013.

When did Voyager 2 cross into interstellar space?

It was then 119.7 AU from the Sun and moving at 15.3 km/s.

What is the boundary where the solar wind slows to subsonic speed called?

Voyager 1 crossed it in December 2004 at 94 AU; Voyager 2 in 2007, about 1.6 billion km closer to the Sun.

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?

Scientists think they form where the Sun's magnetic field becomes warped at the edge of the Solar System.

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

It was shot from about 6 billion km as part of that day's Family Portrait of the Solar System, and Carl Sagan made it famous.

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

The camera software has since been deleted from the spacecraft, and the ground systems to read images no longer exist.

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

The 12-inch record carries sounds and pictures of Earth plus directions for playing it.

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

New software routed around the faulty block, and engineering data resumed in April 2024.

Roughly how long is a round-trip radio signal to Voyager 1 as of the 2023 repair?

Each command and its answer take nearly two days, which made the memory-chip diagnosis slow going.

What Guinness record does the Voyagers' Computer Command System hold?

It has been running since 20 August 1977 on plated-wire memory and 7400-series chips.

Which star will Voyager 1 pass within 1.6 light-years of in about 40,000 years?

Voyager 2 will approach Ross 248 on the same timescale and Sirius in 296,000 years.

In which constellation direction is Voyager 1 heading?

It is climbing 35 degrees north of the ecliptic toward the solar apex, while Voyager 2 heads south toward Pavo.

Which older probes did Voyager 1 overtake in the 1990s to become the most distant human object?

New Horizons left Earth faster but is slower now, because Voyager 1 picked up extra speed at Saturn.

How many Voyager spacecraft were actually built?

VGR 77-2 was the test spare; 77-1 and 77-3 flew as Voyagers 1 and 2.