Voyager are two space probes destined to visit Jupiter and Saturn, to study the limits of the solar system and to explore the immediate interstellar space.

The twin Voyager probes are one of humanity’s great landmarks. Currently, both are as far as humanity has gone with their own creation.

For more than four decades, both probes have helped study the limits of the solar system and also what lies between the stars, interstellar space.

The original mission of the Voyager probe was to visit Jupiter and Saturn in order to provide detailed images of these two planets and their moons.

The Voyager probe before being launched into space. Credit: NASA

Voyager technical components

Each of the two Voyager robotic probes weighs 722 kilograms.

The elements that each of the probes has are:

  • A high gain antenna, 3.70 meters in diameter, attached to the ten-sided hollow polygonal body that houses the electronics.
  • A square panel that houses the optical calibration photographic lens and excess heat radiator.
  • Three radioisotope thermoelectric generators, mounted end-to-end in one of the arms.
  • Two plasma and radio wave antennas.
  • Two high-field and low-field magnetometers, which after launch are 13 meters apart, at the ends of one arm.
  • A cosmic ray subsystem.
  • A low energy charged particle detector.
  • A plasma spectrometer.
  • An infrared interferometer spectrometer.
  • Three cameras.
  • An ultraviolet spectrometer.
  • A photopolarimetric system.
  • A three-element radioisotope thermoelectric generator.
  • A gold disc with messages attached to one side of the probe.

Both probes have a gold disc attached to one side. The gold disc contains a message for possible extraterrestrial intelligent beings who find it.

Image of the gold record, entitled “Sounds of the Earth”. Credit: Wikipedia

The gold record carries a recording of scenes and sounds on Earth, including the sounds of whales. The discs also contain music and greetings spoken in 54 languages.

The content of the recording was selected by NASA and by a committee chaired by Carl Sagan.

Voyager-1 launch

Voyager-1 was launched on September 5, 1977 from NASA’s Kennedy Space Center, Cape Canaveral, aboard a Titan rocket, 16 days after the launch of its twin, Voyager-2.

Titan III
Voyager-1 embarks on the Titan III rocket. Credit: NASA.

During the course of its journey, Voyager-1’s initial velocity was increased, using assisted gravitational pulls.

Thanks to this method, following at a higher speed and a shorter trajectory, Voyager-1 reached Saturn nine months before Voyager-2.

Approach to Jupiter

Fourteen months after its launch, Voyager-1 was in the vicinity of Jupiter, at a distance of 278,000 km.

From January to April 1979, Voyager-1 sent its first photographs of this gigantic planet. In all, the probe took 19,000 pictures of Jupiter.

The space probe approached 18,641 km from the moon Io; And, for the first time, astronomers were able to observe images of volcanic activity outside Earth.

Luna IO
Image of the volcanic activity of the moon Io. Credit: Wikipedia.

Approach to Saturn

Accelerated by Jupiter’s gravitational field, Voyager-1 reached Saturn on November 12, 1980, three years after the start of its journey.

When he had gotten closer to a distance of 124,200 km from Saturn, he began taking pictures of the ringed planet.

The photographs showed complex structures in the ring system and new data from the atmosphere of Saturn and its moon Titan, from which it passed within 6,500 km.

The Saturn system recreated in a photomontage of images taken by the Voyager probes. Credit: Wikipedia.

In an artistic composition, the image shows: on the front, the moon Dione; rising behind, Saturn and Mimas; disappearing in the distance to the right, Thetis; outside the rings of Saturn on the left, Enceladus and Rhea; and at the top, at a distance, Titan.

Approach to the moon Titan

Because the photographs uncovered an atmosphere on Titan, mission controllers decided that Voyager-1 would make a new approach to this moon.

One of the most beautiful artistic images of Titan. Credit: British cartoonist Mark Garlick.

This second approach to Titan increased the gravitational momentum of the probe, moving it away from the plane of the ecliptic and ending its planetary mission.

On February 17, 1998, Voyager-1 was 10 billion km from Earth, a record set ten years earlier by the Pioneer 10 probe.

In September 2004, when he had been traveling through space for 27 years, the Voyager-1 was at a distance of 14,000 million kilometers from the Sun, outside the limits of the solar system.

In interstellar space

In 2005, NASA declared that Voyager-1 had reached the zone called the termination shock front.

On July 7, 2009, Voyager-1 was 16 billion kilometers from the Sun when it entered the so-called “heliofund” zone, an area between the solar system and interstellar space.

At this distance, it took more than fourteen hours for Voyager 1 signals to reach the control center at the Jet Propulsion Laboratory in California.

Since April 8, 2011, 17 billion kilometers from the Sun, Voyager 1 detected a change in the flow of particles, an indication that it was leaving the heliosphere.

Diagram showing the outer extent of the heliosphere. Credit: NASA 1999, Wikipedia.

This stream of charged particles forms a bubble around our solar system. This kind of bubble is called a heliosphere.

The information collected by Voyager 1, made it known that the solar wind travels at “supersonic” speed, until it crosses an area called the heliopause, in which the wind drastically slows down and heats up.

In 2012, Voyager-2 also left the influence of the Sun and entered interstellar space.

Both probes, the first human-made objects that managed to travel through interstellar space, continue to send data.

How Voyagers are powered

Having to travel very far from the Sun, solar panels are of no use in these probes.

Instead of solar panels, the Voyagers power their three generators, which convert the heat from the radioactive decay of plutonium into electricity.

Voyager’s power supplies are generators that run on Plutonium-238, in the form of its oxide PuO2. Credit: web “”.

The problem with generators is that, over time, they lose power as the plutonium breaks down.

Ultimately, the probe has no way to “recharge”, so NASA engineers have been constantly looking for how to make these generators more efficient. They have lasted 42 years, in battery saving mode.

However, as of 2007, due to lack of energy, various systems had to be switched off: planetary radio astronomy, ultraviolet radiation scanning and observations, data tape, gyroscopes.

It has been admirable to maintain a space probe that continues to function for more than 40 years.

However, it is known that after the year 2025 it will not be possible to power any instrument on the probe.

Where is Voyager

In the year 2020, the Voyager-1 probe was 22,000 million kilometers from the Sun and was moving away at a speed of 17 km / sec.

At its present location, the speed of the solar wind has dropped to zero. In the region called the heliopause, the solar wind begins to turn on itself when it hits particles in interstellar space.

Voyager-1 was the first human-made object to pass the heliopause and into interstellar space, heading toward the center of the Milky Way.

Espacio interestelar
NASA Voyagers have been traveling through space for 42 years. Credit: photo by Sciencephoto.

On November 28, 2017, NASA scientists managed to reorient the Voyager antenna towards Earth, thanks to propellants that are at the back of the probe.

The reorientation could be done by pulses of 10 milliseconds; a very complicated precision maneuver, because the control signals took 19 hours and 35 minutes to reach the probe.

In other words, each message and command that is ordered from Earth takes 19 hours to reach the probe, then you have to wait an additional 19 hours for the return message from the probe to arrive.

Day and a half, just to find out if an order given to the probe has taken effect or not.

This procedure is expected to increase the useful life of the probe until at least the year 2025.