Voyager spacecraft

Voyager Probes: Top 10 Amazing Facts To Make You Awestruck

The Voyager 1 and 2 were the iconic spacecraft of NASA from the 1970s that made the first detailed observations of the Outer Solar System. They made several groundbreaking discoveries and took iconic images. They are still active and taking scientific measurements, enough though their power levels are decreasing. Voyagers 1 and 2 are now so far away from the Sun that the Solar wind does not have an influence. But they still have a long way to go to completely exit the Solar System. They are still in communication with NASA’s Deep Space Network. Due to their power coming from nuclear generators, the power output is constantly decreasing. Only a few of the necessary scientific instruments are ‘ON’ at this stage. Let us look at some of the most mind-blowing facts about the Voyager mission.

10. The Voyager probes made groundbreaking new discoveries in Jupiter

The animation of the series of images taken for every Jupiter day ~ 10 hours, by Voyager 1. It consists of 66 images taken from January 6, 1979 to February 3, 1979. The distance range in this animation is from 58 to 31 million kilometers from Jupiter.
The animation of the series of images taken for every Jupiter day ~ 10 hours, by Voyager 1. It consists of 66 images taken from January 6, 1979, to February 3, 1979. The distance range in this animation is from 58 to 31 million kilometers from Jupiter. Credits – NASA Jet Propulsion Laboratory, Source.

Voyager 1 reached Jupiter earlier than Voyager 2. The closest approach to Jupiter happened on March 5, 1979, at a distance of 3,49,000 km from Jupiter. Voyager 2 had the closest approach to Jupiter on July 9, 1979, at a distance of 5,76,000 km from Jupiter. They made groundbreaking new discoveries about Jupiter and its moons. The most unexpected discovery was the volcanic activity on Jupiter’s moon Io. This was the first time an active volcano was observed other than the Earth.

9. Voyager 1 made a close approach to Saturn’s moon Titan

Saturn's moon Titan as seen by Voyager 1 at a distance of 4.5 million km.
Saturn’s moon Titan was seen by Voyager 1 at a distance of 4.5 million km.
Credits – NASA, Source.

Just like today, there was much interest in studying Saturn’s moon Titan as it was found to have a thick atmosphere. The trajectory of Voyager 1 was planned in such a way that it can study the Titan very closely. Voyager probes made detailed measurements of the density, composition, and temperature of the atmosphere of Titan. It also measured Titan’s mass accurately. However, the thick atmosphere prevented the photographing of the Titan’s surface. The flyby of Titan made Voyager 1 change its trajectory and thus prevented it from visiting Uranus and Neptune.

8. The probes are powered by the decay of Radioactive materials

Two Multi Hundred Watt (MHW) Radioisotope thermoelectric generators (RTG) used in the Voyager probes.
Two Multi Hundred Watt (MHW) Radioisotope thermoelectric generators (RTG) were used in the Voyager probes. Credits – NASA, Source.

Given the extreme distances the probes had to cover in Outer space, the conventional power sources for spacecraft, such as solar panels were not useful. The only way to power the probes for such a long time and distances was by nuclear source. Both the Voyager spacecraft get their power from Multihundred-Watt radioisotope thermoelectric generators (MHW RTG). Each spacecraft had three of these generators. At launch, the power output for each spacecraft was 470 watts. Each of these generators weighed 37.7 kg and was powered by Plutonium Pu-238 radioactive material.

7. Voyager probes are the farthest artificial objects from the Earth

Artist's concept of Voyager spacecraft in flight in deep space.
Artist’s concept of Voyager spacecraft in flight in deep space. Credits – NASA/JPL, Source.

Voyager 1 is presently the farthest man-made object from Earth. It was 23,33,72,85,177 km from Earth on June 26, 2022 at 12:07 PM Indian Standard Time (IST). Voyager 2 is at a distance of 19,41,62,42,096 km from Earth on June 26, 2022, at 12:07 PM Indian Standard Time (IST). Voyager 1 is farther away because Voyager 2 was put on a trajectory to study the planets Uranus and Neptune as well. You can check the status of the Voyager probes including the distance from the Earth and the Sun here – https://voyager.jpl.nasa.gov/mission/status/.

6. By the mid-2020s, the probes will not have enough power to conduct measurements

The schematic diagram of the Voyager spacecraft structure.
The schematic diagram of the Voyager spacecraft structure. Credits – NASA, Source.

After the Voyagers completed their exploration of the outer solar system they were repurposed to study the outer edges of the solar system. This mission was known as the Voyager Interstellar Mission (VIM). During this mission, the Voyagers made many remarkable and unexpected discoveries, such as the increase in density of the plasma. However, the scientific instruments and devices on board the probes are being gradually turned off to save power. The power output from the radioactive generator is also continuously decreasing. Hence the Voyager probes may not be able to communicate with Earth after that.

5. Till date, Voyager 2 is the only spacecraft to visit Uranus

This is how you would see Uranus from a distance of 9.1 million km. This image was taken by Voyager 2 on January 17, 1986.
This is how you would see Uranus from a distance of 9.1 million km. This image was taken by Voyager 2 on January 17, 1986. Credits – NASA/JPL, Source.

On January 24, 1986, Voyager 2 came to just 81,500 km above Uranus. It was the first spacecraft to study Uranus from a close range. It also discovered 11 new moons of Uranus. It also studied the extreme tilt of the orbital axis. It was also discovered on Uranus’s moon Miranda. Voyager 2 discovered that Uranus also had rings. The fact that Uranus had a magnetic field was discovered by Voyager 2. Voyager 2 also discovered strange geological features in Miranda.

4. Voyager 2 was launched before Voyager 1

The launch of Voyager 2 in 1977.
The launch of Voyager 2 in 1977. Credits – NASA/MSFC, Source.

Even though Voyager 2 was second in the Voyager series, it was launched 16 days before Voyager 1. It was launched on August 20, 1977 by a Titan III-Centaur rocket. This was because the Voyager 2 was launched on a more longer and circular trajectory. Voyager 1 was launched on Spetember 5, 1977. Anyhow, Voyager 1 was the first to reach Jupiter as well as Saturn. Voyager 1 overtook Voyager 2 just four months after launch on December 19, 1977.

3. The Voyager Program was possible due to the rare alignment of outer Planets that occurs once in 175 Years

The trajectories of the Voyager probes inside the solar system.
The trajectories of the Voyager probes inside the solar system. Credits – NASA, Source.

Gary Flandro was an aerospace engineer working at the Jet Propulsion Laboratory of NASA in 1964. He was studying the ways to explore the Outer Solar System. He found that the outer planets were aligned in a rare manner in the 1970s that happens once in 175 years. He found out that using the gravity assist techniques, the trip to the outer solar system can be reduced to 10 years time instead of the usually required 40 years. His work paved the way for the Planetary Grand Tour Program by NASA. But due to the enormous costs of the program, it was canceled and replaced by the Voyager program.

2. Voyager 1 took the ‘Family Portrait of the Solar System on February 4, 1990

This simulated view was created using the NASA's Eyes on the Solar System app. It approximates Voyager 1's perspective when it captured the 'Family Portrait of the Solar System'. This includes the iconic 'Pale Blue Dot' image.
This simulated view was created using NASA’s Eyes on the Solar System app. It approximates Voyager 1’s perspective when it captured the ‘Family Portrait of the Solar System’. This includes the iconic ‘Pale Blue Dot’ image. Credits – NASA/JPL-Caltech, Source.

After the exploration of Jupiter and Saturn, Voyager 1 was moving to the edges of the solar system at an extremely high speed. But then in 1990, just before the cameras were turned off, Voyager 1 was programmed to capture the portrait of the solar system. However, the portrait is not a single picture, but a mosaic of 60 images. The iconic ‘Pale Blue Dot’ is a part of the Family Portrait. Sun had to be imaged using a different filter. Astronomer Carl Sagan had campaigned hard to have this picture taken. This portrait and the ‘Pale Blue Dot’ picture are one of the most iconic images ever taken by humanity.

1. A disc on both probes containing information about Earth and life on Earth is intended for intelligent extraterrestrials

The Voyager Golden Record.
The Voyager Golden Record. Credits – NASA, Source.

Each of the Voyager spacecrafts have a ‘Voyager Golden Record’ with them. These records contain various sounds and images of Earth and life on Earth. They depict different human cultures. The Pioneer 10 and 11 space probes had carried plaques. The contents in the golden record was selected by a committee chaired by eminent astronomer Carl Sagan. They have spoken greetings in 55 languages, various images and sounds depicting life on Earth, greetings from the United Nations Secretary General and the President of the United States, among other things. Even though both Voyagers’ trajectory are not directed towards any star, both will come close to stars in the distant future. The nearest of those is when Voyager 1 will pass at a distance of 1.6 light years from the star Gliese 445 in about 40,000 years.

Which of these facts were the most surprising and unexpected to you? Write in the comments below.

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