Voyager 1 facts for kids

Quick facts for kids
Voyager 1

Model of the Voyager spacecraft design
Mission type	Outer planetary, heliosphere, and interstellar medium exploration
Operator	NASA/Jet Propulsion Laboratory
Mission duration	47 years, 9 months, 14 days elapsed Planetary mission: 3 years, 3 months, 9 days Interstellar mission: 44 years, 6 months, 6 days elapsed
Spacecraft properties
Spacecraft type	Mariner Jupiter-Saturn
Manufacturer	Jet Propulsion Laboratory
Launch mass	815 kg (1,797 lb)
Dry mass	721.9 kg (1,592 lb)
Power	470 watts (at launch)
Start of mission
Launch date	September 5, 1977, 12:56:00 (1977-09-05UTC12:56Z) UTC
Rocket	Titan IIIE
Launch site	Cape Canaveral Launch Complex 41
End of mission
Last contact	TBD
Flyby of Jupiter
Closest approach	March 5, 1979
Distance	349,000 km (217,000 mi)
Flyby of Saturn
Closest approach	November 12, 1980
Distance	124,000 km (77,000 mi)
Flyby of Titan (atmosphere study)
Closest approach	November 12, 1980
Distance	6,490 km (4,030 mi)
Flagship ← Voyager 2 Galileo →

Voyager 1 is a space probe launched by NASA on September 5, 1977. It is part of the Voyager program. Its main job is to explore the outer Solar System and the space between stars, called the interstellar medium. Voyager 1 was launched 16 days after its twin, Voyager 2.

The probe talks to Earth using the NASA Deep Space Network. This network sends commands to Voyager 1 and receives data back. NASA and the JPL track its distance and speed in real-time. As of late 2023, Voyager 1 is the farthest human-made object from Earth. It is about 162 AU away.

Voyager 1 flew past Jupiter, Saturn, and Saturn's largest moon, Titan. NASA chose to study Titan because it has a thick atmosphere. The probe looked at the weather, magnetic fields, and rings of Jupiter and Saturn. It was the first probe to send back detailed pictures of their moons.

The mission's goal is to study the edges of the Solar System and begin exploring interstellar space. Voyager 1 crossed into interstellar space on August 25, 2012. This made it the first spacecraft to do so. In 2017, engineers tested its thrusters for the first time since 1980. This helped extend the mission for a few more years. Voyager 1's mission is expected to continue until at least 2025. Its power source might even keep some instruments working until 2036.

In December 2023, NASA announced a problem with Voyager 1's data system. It could not send useful scientific data. By April 2024, engineers found a solution and are working to fix it.

Building the Voyager 1 Spacecraft

How the Mission Started

In the 1960s, scientists thought about a "Grand Tour" to study the outer planets. This led NASA to start planning a mission in the early 1970s. Information from the Pioneer 10 spacecraft helped engineers design Voyager 1. They made it stronger to handle the intense radiation around Jupiter. They even added strips of kitchen aluminum foil to some cables for extra protection.

Voyager 1 was first planned as "Mariner 11". It was part of the Mariner program. But due to budget cuts, the mission became a flyby of only Jupiter and Saturn. It was then called the Mariner Jupiter-Saturn probes. Later, the name changed to Voyager. This was because the probe's design became very different from earlier Mariner missions.

Parts of the Spacecraft

Voyager 1 was built by the Jet Propulsion Laboratory. It has 16 thrusters that use hydrazine fuel. It also has three-axis stabilization gyroscopes. These help keep the probe's radio antenna pointed towards Earth. These parts work together in the Attitude and Articulation Control Subsystem (AACS). The spacecraft also carries 11 scientific instruments. These instruments study planets and other objects in space.

How Voyager 1 Communicates

The radio communication system of Voyager 1 was built to work far beyond the Solar System. It has a 3.7-meter (12-foot) wide Cassegrain antenna. This antenna sends and receives radio waves. It uses three Deep Space Network stations on Earth. Voyager 1 usually sends data to Earth at 2.3 GHz or 8.4 GHz. Signals from Earth are sent at 2.1 GHz.

When Voyager 1 cannot talk directly to Earth, it records data. Its digital tape recorder (DTR) can save about 67 megabytes of data. This data is sent later. As of 2023, it takes over 22 hours for signals from Voyager 1 to reach Earth.

Powering the Probe

Voyager 1 has three radioisotope thermoelectric generators (RTGs). These are mounted on a long arm. Each RTG holds 24 pressed plutonium-238 oxide spheres. At launch, the RTGs made about 470 watts of electric power. The power slowly decreases over time. This is because the fuel has an 87.7-year half-life. But the RTGs will keep some operations going until 2025.

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  Diagram of RTG fuel container, showing the plutonium-238 oxide spheres

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  Diagram of RTG shell, showing the power-producing silicon-germanium thermocouples

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  Model of an RTG unit

Computers on Board

The cameras on Voyager 1 are not fully automatic. A special computer, the Flight Data Subsystem (FDS), controls them. This computer holds the instructions for taking pictures. Most space probes today have cameras that work completely on their own.

Another computer, the computer command subsystem (CCS), controls the cameras. The CCS has programs for decoding commands and fixing problems. It also helps point the antenna. This computer is an improved version of one used in the 1970s Viking orbiters.

The Attitude and Articulation Control Subsystem (AACS) keeps the spacecraft pointed correctly. It makes sure the high-gain antenna aims at the Earth. It also controls how the probe changes its direction. Both Voyager probes have the same custom-built AACS systems.

Science Tools on Voyager 1

Voyager 1 carries several scientific instruments. These tools help scientists learn about space.

Voyager 1's Journey Through Space

Launch and Path

Voyager 1 lifted off atop a Titan IIIE.

Animation of Voyager 1's trajectory from September 1977 to December 31, 1981
       Voyager 1  ·       Earth ·       Jupiter ·       Saturn ·       Sun

Voyager 1 launched on September 5, 1977. It lifted off from Cape Canaveral Air Force Station in Florida. It rode on a Titan IIIE rocket. Its twin, Voyager 2, had launched two weeks earlier. But Voyager 1 took a shorter path and reached Jupiter and Saturn first.

The launch of Voyager 1 almost failed. The rocket's second stage stopped too early. But the Centaur stage's computers took over. They burned for much longer than planned to make up for it. The Centaur ran out of fuel just 3.4 seconds before it needed to. If this had happened to Voyager 2, it would not have reached its correct path. Jupiter was in a better position for Voyager 1s launch than for Voyager 2s.

Flying Past Jupiter

Animation of Voyager 1's trajectory around Jupiter
      Voyager 1 ·       Jupiter ·       Io ·       Europa ·       Ganymede ·       Callisto

The trajectory of Voyager 1 through the Jupiter system

Voyager 1 started taking pictures of Jupiter in January 1979. It came closest to Jupiter on March 5, 1979. It was about 349,000 kilometers (217,000 miles) from the planet's center. Most of its observations of Jupiter's moons, rings, and magnetic fields happened during the 48 hours around this closest approach. Voyager 1 finished photographing Jupiter in April 1979.

A big surprise was finding active volcanoes on Jupiter's moon Io. This was the first time active volcanoes were seen on another body in the Solar System. Io's activity seems to affect Jupiter's entire magnetosphere. This is the area around Jupiter controlled by its strong magnetic field. Materials like sulfur, oxygen, and sodium from Io's volcanoes were found at the edge of Jupiter's magnetosphere.

The two Voyager probes made many important discoveries about Jupiter. They learned about its moons, radiation belts, and its never-before-seen planetary rings.

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  Jupiter's Great Red Spot, a huge storm bigger than Earth, as seen from Voyager 1

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  Sulfur-rich lava flows from the volcano Ra Patera on Io

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  The eruption plume of the volcano Loki rises 160 km (100 mi) over the edge of Io

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  Europa's surface, showing signs of active geology, from 2.8 million km (1.7 million mi).

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  Ganymede's icy surface, with bright impact sites, from 253,000 km (157,000 mi).

Flying Past Saturn

Animation of Voyager 1 around Saturn
      Voyager 1 ·       Saturn ·       Mimas ·       Enceladus  ·       Tethys ·       Rhea ·       Titan

After Jupiter, both Voyager probes used Jupiter's gravity to speed up. They then traveled to Saturn and its moons and rings. Voyager 1 reached Saturn in November 1980. Its closest approach was on November 12, 1980. It came within 124,000 kilometers (77,000 miles) of Saturn's cloud tops. The probe's cameras saw complex structures in the rings of Saturn. Its instruments also studied the atmospheres of Saturn and its giant moon Titan.

Voyager 1 found that about seven percent of Saturn's upper atmosphere is helium. Most of the rest is hydrogen. Scientists think the heavier helium might be slowly sinking through Saturn's hydrogen. This could explain why Saturn gives off more heat than it gets from the Sun. Winds on Saturn blow very fast. Near the equator, winds were measured at about 500 meters per second (1,100 mph).

The Voyager probes found aurora-like ultraviolet light in Saturn's atmosphere. These lights are similar to the Northern and Southern Lights on Earth. Both Voyager probes measured Saturn's day length. It is 10 hours, 39 minutes, and 24 seconds long.

Voyager 1's mission included a flyby of Titan, Saturn's largest moon. Scientists knew Titan had an atmosphere. Pictures from Pioneer 11 in 1979 showed it was thick and complex. This made scientists even more interested. The flyby of Titan happened as the spacecraft entered the Saturn system. This was to avoid any damage closer to Saturn. Voyager 1 passed behind Titan as seen from Earth and the Sun. This allowed scientists to study Titan's atmosphere using the probe's radio signals. The thick haze on Titan prevented seeing its surface. But measurements suggested there might be lakes of liquid hydrocarbons on the surface.

The path for Voyager 1 was chosen to get the best view of Titan. This path took it below Saturn's south pole and out of the plane where most planets orbit. This ended its main planetary mission. If Voyager 1 had not been able to study Titan, Voyager 2's path would have changed to do so. This would have stopped Voyager 2 from visiting Uranus and Neptune.

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  Crescent Saturn from 5.3 million km (3.3 million mi), four days after closest approach

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  Voyager 1 image of Saturn's narrow, twisted and braided F Ring.

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  Mimas at a range of 425,000 km (264,000 mi) from Voyager 1

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  Tethys, with its giant rift valley Ithaca Chasma, from 1.2 million km (746,000 mi).

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  Fractured 'wispy terrain' on Dione's trailing side.

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  The icy surface of Rhea is covered with impact craters.

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  Titan's thick haze layer is shown in this enhanced Voyager 1 image.

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  Layers of haze, made of complex organic compounds, covering Saturn's moon Titan.

Leaving the Solar System

The Family Portrait of the Solar System taken by Voyager 1 (February 14, 1990)

Updated version of the Family Portrait (February 12, 2020)

The Pale Blue Dot image showing Earth from 6 billion km (3.7 billion mi) away. It looks like a tiny dot (the bluish-white speck) in deep space.

On February 14, 1990, Voyager 1 took the first "family portrait" of the Solar System from far away. This included the famous image of Earth called the Pale Blue Dot. Soon after, its cameras were turned off to save power. The software for the cameras was removed from the spacecraft. It would be very hard to get them working again.

On February 17, 1998, Voyager 1 became the farthest spacecraft from Earth. It passed Pioneer 10. Voyager 1 travels at about 17 kilometers per second (11 mi/s). This is the fastest speed away from the Sun for any spacecraft.

As Voyager 1 moved towards interstellar space, its instruments kept studying the Solar System. Scientists used its plasma wave experiments to find the heliopause. This is the boundary where the solar wind slows down and meets the interstellar medium. As of 2013, the probe was moving at about 38,026 mph (61,199 km/h) relative to the Sun. At this speed, Voyager 1 travels about 325 million miles (523 million km) each year. This is about one light-year every 18,000 years.

Crossing the Termination Shock

Scientists at Johns Hopkins University believe Voyager 1 entered the termination shock in February 2003. This is where the solar wind slows down to slower-than-sound speeds. Some scientists had doubts because Voyager 1's solar-wind detector stopped working in 1990. So, they had to guess based on data from other instruments.

In May 2005, NASA announced that Voyager 1 was in the heliosheath. This is the region beyond the termination shock. On December 15, 2004, at 94 AU from the Sun, the craft crossed the termination shock.

Through the Heliosheath

On March 31, 2006, amateur radio operators in Germany managed to track Voyager 1. They received its radio waves. This was the first time amateurs had tracked the probe.

On December 13, 2010, it was confirmed that Voyager 1 had passed the area where the solar wind flows outward. This was measured by the Low Energy Charged Particle device. Scientists think the solar wind turns sideways here because of pressure from interstellar wind. Since June 2010, no solar wind was detected. This proved the event happened. At this time, the spacecraft was about 116 AU from the Sun.

In March 2011, Voyager 1 was told to change its direction. This was to measure the sideways motion of the solar wind. It rotated 70 degrees. This was the first major maneuver since the Family Portrait photo in 1990. After the roll, the spacecraft easily reoriented itself. It continued sending data back to Earth.

On December 1, 2011, Voyager 1 detected Lyman-alpha radiation from the Milky Way galaxy. This radiation had been seen from other galaxies. But interference from the Sun made it hard to see from our own galaxy.

On December 5, 2011, NASA announced that Voyager 1 entered a new area. They called it a "cosmic purgatory". In this area, charged particles from the Sun slow down and turn inward. The Solar System's magnetic field also doubles in strength. High-energy electrons from outside increase 100 times. The inner edge of this area is about 113 AU from the Sun.

Reaching the Heliopause

In June 2012, NASA said the probe was detecting changes that suggested it was reaching the heliopause. Voyager 1 saw a big increase in charged particles from interstellar space. These particles are usually pushed away by the solar winds. This meant the craft was entering the space between stars.

Voyager 1 became the first spacecraft to cross the heliopause in August 2012. It was then 121 AU from the Sun. This was confirmed a year later.

As of September 2012, sunlight took 16.89 hours to reach Voyager 1. The Sun looked about 30 times brighter than the full Moon from the spacecraft. The spacecraft was traveling at 17.043 kilometers per second (10.590 mi/s) relative to the Sun. At this speed, it would take about 17,565 years to travel one light-year. The closest star, Proxima Centauri, is about 4.2 light-years away. It would take Voyager 1 73,775 years to reach it if it were heading there. Voyager 1 is actually heading towards the constellation Ophiuchus.

In late 2012, data from the spacecraft showed it had passed through the heliopause. There was a steady rise in high-energy particles (from supernova explosions). At the same time, there was a big drop in low-energy particles (from the Sun).

Ed Roelof, a space scientist, said that most scientists agreed these signs meant Voyager 1 had crossed the boundary. However, the magnetic field direction had not changed much. This made some wonder if they had misunderstood the edge of the heliosphere.

On December 3, 2012, Voyager project scientist Ed Stone said Voyager found a new region of the heliosphere. He said, "We're still inside, apparently. But the magnetic field now is connected to the outside." The magnetic field in this region was 10 times stronger. This was expected to be the last barrier before the spacecraft left the Solar System completely.

Entering Interstellar Space

In March 2013, it was announced that Voyager 1 might be the first spacecraft to enter interstellar space. It had detected a big change in the plasma around it on August 25, 2012. But it was not officially confirmed until September 12, 2013. At that time, it was officially confirmed that it had entered interstellar space.

In 2013, Voyager 1 was leaving the Solar System at about 3.6 AU per year. Voyager 2 was slower, at 3.3 AU per year. Voyager 1 increases its lead over Voyager 2 each year.

On May 18, 2016, Voyager 1 reached 135 AU from the Sun. By September 5, 2017, it was about 139.64 AU from the Sun. This is just over 19 light-hours away. You can follow its progress on NASA's website.

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  Plot showing a dramatic increase in the rate of cosmic ray particle detection by the Voyager 1 spacecraft (October 2011 through October 2012)

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  Plot showing a dramatic decrease in the rate of solar wind particle detection by Voyager 1 (October 2011 through October 2012)

Voyager 1 and other probes that are in or on their way to interstellar space, except New Horizons.

On September 12, 2013, NASA officially confirmed that Voyager 1 had reached the interstellar medium in August 2012. The accepted date is August 25, 2012. This is when changes in the density of energetic particles were first seen. Most space scientists now agree that a change in magnetic field direction is not needed to confirm crossing the heliopause.

A key finding was an 80-fold increase in electron density. This was based on plasma oscillations seen starting April 9, 2013. These were caused by a solar outburst in March 2012. Electron density is expected to be much higher outside the heliopause. Weaker oscillations in October and November 2012 gave more data. Voyager 1's plasma spectrometer stopped working in 1980. So, indirect measurements were needed. In September 2013, NASA released audio recordings of these plasma waves. These were the first measured in interstellar space.

People often say Voyager 1 left the Solar System when it left the heliosphere. But these are not the same. The Solar System is much bigger. It includes all bodies that orbit the Sun. The craft is still far from the aphelion of Sedna. It has not yet entered the Oort cloud. This cloud is the source of long-period comets and is considered the outermost part of the Solar System.

In October 2020, astronomers reported an unexpected increase in density in the space beyond the Solar System. This was detected by Voyager 1 and Voyager 2. This suggests that the density changes are a large feature of the local interstellar medium.

In May 2021, NASA reported continuously measuring the density of material in interstellar space for the first time. They also detected interstellar sounds for the first time.

In May 2022, NASA reported that Voyager 1 was sending "mysterious" telemetry data. The spacecraft was still working, but the problem was with the Attitude Articulation and Control System (AACS). NASA's Jet Propulsion Laboratory (JPL) said the AACS was working but sending bad data. The problem was traced to the AACS sending data through a computer that had not been used for years. This caused the data to be corrupted. In August 2022, NASA sent a command to the AACS to use another computer. This fixed the problem. Scientists are still investigating what caused the initial switch.

The Future of Voyager 1

How Long Will it Last?

Image of Voyager 1's radio signal on February 21, 2013

In December 2017, NASA successfully fired Voyager 1's trajectory correction thrusters. This was the first time since 1980. These thrusters help keep the probe's antenna pointed towards Earth. Using them allowed Voyager 1 to keep sending data for two to three more years.

Voyager 1's electrical power is slowly decreasing. The Voyager team has to decide which instruments to keep on. Heaters and other systems have been turned off. The instruments that study particles and fields are most important. They send back key data about interstellar space. Engineers expect the spacecraft to operate at least one science instrument until around 2025.

Thruster Concerns

Some thrusters that control the spacecraft's direction are not working well. This is due to clogs in their hydrazine fuel lines. The spacecraft no longer has a backup for its thruster system. Suzanne Dodd, the Voyager project manager, said "everything onboard is single-string." This means there are no backups for many parts. NASA decided to change the spacecraft's computer software. This will help reduce how fast the hydrazine lines clog. NASA will test this software on Voyager 2 first, as it is closer to Earth. Then they will put it on Voyager 1.

The Far Future

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  Simulated view of Voyager 1 relative to the Solar System on August 2, 2018.

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  Simulated view of the Voyager probes relative to the Solar System and heliopause on August 2, 2018.

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  In about 50,000 years Voyager 1 will be as distant as several nearby stars

If Voyager 1 does not hit anything and is not brought back, the New Horizons space probe will never pass it. Even though New Horizons launched faster, Voyager 1 got extra speed from flying past multiple planets. New Horizons only got one boost from Jupiter. As of 2018, New Horizons travels at about 14 kilometers per second (8.7 mi/s). This is 3 kilometers per second (1.9 mi/s) slower than Voyager 1.

Voyager 1 is expected to reach the Oort cloud in about 300 years. It will take about 30,000 years to pass through it. The Oort cloud is a huge shell of icy objects far beyond the planets. Voyager 1 is not heading towards any specific star. But in about 40,000 years, it will pass within 1.6 light-years of the star Gliese 445. This star is currently 17.1 light-years from Earth. NASA says that "The Voyagers are destined—perhaps eternally—to wander the Milky Way." In 300,000 years, it will pass very close to another star called TYC 3135-52-1.

The Golden Record

Voyager Golden Record

Each Voyager space probe carries a gold-plated audio-visual disc. This is in case the spacecraft is ever found by intelligent life from other planets. The disc has photos of Earth and its lifeforms. It also has scientific information. There are spoken greetings from people like the Secretary-General of the United Nations and the President of the United States.

The disc also has a collection of sounds called "Sounds of Earth". This includes sounds of whales, a baby crying, and waves on a shore. It also has music by artists like Wolfgang Amadeus Mozart, Blind Willie Johnson, and Chuck Berry. Other classic and traditional music from around the world is also included. The record also has greetings in 55 different languages.

See Also

In Spanish: Voyager 1 para niños