Voyager 1: Humankind’s Creation in Deep Space
By Arpita Saha
“The Earth is the cradle of Humanity, but mankind cannot stay in the cradle forever.”Konstantin Tsiolkovsky
What comes to your mind first when you hear the name of Voyager 1? Perhaps you’re aware that it’s the name of a spacecraft that has been traveling through space for a very long time. Perhaps you know of it due to the famous Pale Blue Dot image or because of it being the first thing created by humanity to travel into interstellar space. But does it mean anything more to you?
Voyager 1 has always inspired me since childhood. To me, it means way a lot more than just a bunch of instruments travelling in deep space. The accomplishments of Voyager 1 along with Carl Sagan’s incredible “Pale Blue Dot” speech (and subsequent book) have not only made me fall in love with space and its wonders, but also made me change my way of thinking about life as a whole — a humbling experience for me. It has not only made me understand and appreciate the beauty and meaning of life and all the elementary things of Mother Nature, but also drove me to wonder more and more about science and the mysteries of the Universe. So much science, so many unsolved questions, so much to learn, so many things to discover, so much to understand — a wonderful description of the exciting and meaningful adventure of Voyager 1.
The Purpose and Mission of the Voyager Spacecraft
There was a rare geometric arrangement of the planets Jupiter, Saturn, Uranus, and Neptune in the late 1970s and the 1980s. The Voyager mission was designed to take advantage of this rare geometric arrangement since this would allow spacecraft on a particular flight path to swing from one planet to the next without the need for large onboard propulsion systems, or, in simple words, this would allow a four-planet tour for a minimum of propellant and trip time.
This led to the launch of Voyager 1 and Voyager 2 as outer planet explorers, with Voyager 1 intended to fly by Jupiter and Saturn (with a focus on the large moon, Titan) while Voyager 2 would fly by Jupiter, Saturn, Uranus, and Neptun (and, even until now, Voyager 2 remains the only spacecraft to ever to visit Uranus and Neptune).
The Mission Begins: Leaving the Home Planet Forever
While the spacecraft are named Voyager 1 and Voyager 2, it was actually the latter spacecraft that was launched first. Voyager 2 was launched on August 20, 1977, while Voyager 1 was launched on September 5, 1977. Both of them were launched from the NASA Kennedy Space Center at Cape Canaveral in Florida, and delivered to space aboard Titan-Centaur expendable rockets.
The Main Destination: The Prime Voyager Mission to Jupiter and Saturn
Voyager 1 had its closest approach to Jupiter on 5 March 1979. On the other hand, Voyager 2 had its closest approach to Jupiter on 9 July 1979.
Voyager 1 finished photographing the Jovian system in April 1979, and the discovery of the ongoing volcanic activity on the Galilean moon Io turned out to be the first time for humans to see active volcanoes on another body in the Solar System. The effects on the Jovian system due to the activity of Io was studied — Io apparently being the primary source of matter pervading the Jovian magnetosphere due to volcanic eruptions lofting matter into orbit around the moon. The Voyagers made significant discoveries about Jupiter, its satellites, its radiation belts, and its planetary rings which were never seen before.
Voyager 1 had its closest approach to Saturn on 12 November 1980, while Voyager 2 had its closest approach to Saturn on 25 August 1981.
Voyager 1 detected complex structures in the rings of Saturn as well as studied the atmosphere of both Saturn and its largest moon, Titan (since Voyager 1’s mission also included a flyby to Titan), and measurement of Titan’s atmospheric temperature, composition, and pressure led to speculations that lakes of hydrocarbons could exist on the surface. Both the voyagers found aurora-like ultra-violet emissions of hydrogen at mid-latitudes in the atmosphere (the mystery behind the formation of mid-latitude aurorae still remains unsolved), and aurorae at polar latitudes. The Voyagers also did more significant measurements and discoveries about Saturn, the speed and direction of its winds, and the speed of its rotation.
A Twist in the Journey
The trajectory of Voyager 1, which was designed to send the spacecraft closely past the moon Titan and behind Saturn’s rings, bent the spacecraft’s path inevitably out of the ecliptic plane (the imaginary plane formed from the Earth’s orbit around the Sun). Voyager 2, on the other hand, was aimed to fly by Saturn at a point that would automatically send the spacecraft in the direction of Uranus and then to Neptune, assuming that the spacecraft was still operational and additional funding could be supplied for the continuation of the mission. Hence, NASA provided additional funding to continue operating the two spacecraft and authorized the Jet Propulsion Laboratory (JPL) to conduct a Uranus flyby, and also later authorized the Neptune leg of the mission, which was renamed the Voyager Neptune Interstellar Mission.
The Voyager Interstellar Mission
Voyager 2 encountered Uranus on January 24, 1986, and then had its closest approach to Neptune on August 25, 1989 (it returned detailed photos and other data on the planets, some of their moons, magnetic fields, and ring systems). After that, Voyager 2 continued on below the ecliptic plane and on the course toward interstellar space. Reflecting the Voyagers’ destinations after visiting the outer planets, the project is now known as the Voyager Interstellar Mission.
On August 25, 2012, Voyager 1 crossed into interstellar space, thus leaving behind the heliosphere (the region of space in which the Sun’s stellar environment predominates). The results came to light after a powerful solar eruption was recorded in Voyager 1’s plasma wave instrument between April 9 and May 22, 2013. The eruption caused electrons near Voyager 1 to vibrate. From the oscillations, researchers discovered Voyager 1’s surroundings had a higher density than what is found inside the heliosphere. Researchers then backtracked through Voyager 1’s data and nailed down the official departure date to August 25, 2012. The date was fixed not only by the electron oscillations, but also by its measurements of charged solar particles.
Voyager 2 on the other hand crossed into interstellar space on November 5, 2018. Hence, Voyager 2 became the 2nd spacecraft from earth to cross into interstellar space. The estimated velocity of Voyager 1 with respect to the Sun is 16.9995 kps while that for Voyager 2 is 15.3741 kps (to put this in perspective, the International Space Station orbits Earth while traveling roughly 8 kps, and the fastest train on Earth is about 100 times slower than Voyager 1).
Voyager 1 at the time of writing is at a distance way above 22,000,000,000 km from Earth, while Voyager 2 is at a distance of well over 18,000,000,000 km away. Both of their distances are continuously increasing with the passage of time, or more accurately, with every second. So by the time my article gets published on the website, both the Voyagers will go further away, and away, and away! You can check out the current distances yourself online.
Valentine’s Day, 1990: The Pale Blue Dot
Valentine’s Day is not an official holiday in any nation, but it is celebrated in many places as a special day for honoring love, compassion, and relationships. However, Valentine’s Day, taking place on the 14th of February in our current calendar, is also a very special day in the space community for another reason:
On Valentine’s Day in 1990, the Voyager 1 spacecraft took one of the arguably most important photos in the history of our planet and our species – the Pale Blue Dot image.
On 14 February 1990, while Voyager 1 was roughly 6 billion km (3.7 billion miles) away from the Earth (roughly the same as the distance to the orbit of Pluto), the operators of the spacecraft turned it around so that it’s cameras would face back toward the inner solar system. From this perspective, they took a “family portrait” as a series of images of the worlds of the inner solar system, including Venus, Earth, Jupiter, Saturn, Uranus and Neptune.
In case you are wondering why Voyager 1 did not capture Mercury and Mars in the above image, unfortunately those two worlds were lost in the glare of the Sun relative to Voyager 1. And Pluto fans who might wonder why the little dwarf planet wasn’t included, that world was too faint to be visible. The Sun looked like a bright dot, and, as the Planetary Society later described it, our entire solar system looked like a string of small coloured dots clustered just to the right of the constellation Orion. For me, the Solar Family Portrait also looks as if a child drew some dots on a blackboard with the help of colorful chalks!
Among the images was one that showed our Earth from the greatest distance that it has ever been photographed.
That image is now known as the Pale Blue Dot!
“Look again at that dot. That’s here. That’s home. That’s us.”
That image of our planet from almost 4 billion miles away inspired renowned astronomer Carl Sagan to write his famous “Pale Blue Dot” speech, where he reflected on the image, “…Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light.”
From the outer Solar System, our planet Earth appeared as a simple pale blue dot in the darkness. A sobering and chilling portrait of our planet, but also very inspiring!
What a wonderful Valentine’s Day gift from 1990, especially as that was the day Voyager 1 turned around to see our home planet for the last time before continuing on further and further from us.
The Curious Case of The Golden Record
Beyond its successes exploring the outer planets, traveling into interstellar space before any other spacecraft, being the furthest extension of humanity in space, and taking one of the most famous photographs of all time, Voyager 1 also has another feature that many of us find profound: it bears witness to some facets of humanity and our place in the cosmos in the form of the Voyager Golden Record. The Voyagers are carriers of messages from humanity for potential civilizations in interstellar space!
The Pioneer 10 and 11 spacecraft each carried metal plaques, identifying humanity and our place in space for potential aliens to discover (a very long distance message-in-a-bottle). But for Voyager 1 and 2, similar metal plaques also served as covers for gold-plated phonograph records which had been implanted with audio information intended to communicate a story of our world to extraterrestrial civilization(s). The Voyager records are 30.48 cm (12-inch) gold-plated copper disks containing sounds and images selected to portray the diversity of life and culture on our planet Earth, in order to create the best and most beautiful first impression of our home planet to the extraterrestrial civilization(s).
The information (both audio and imagery) encoded on the record includes 115 images, a variety of natural sounds (such as sounds of surf, winds, thunder, birds, whales, and other animals), musical selections from different cultures and eras, spoken greetings from people in 55 different languages, and printed messages from 39th U.S. President Jimmy Carter and U.N. Secretary General Waldheim. The Golden Record was designed in such a way so as to represent our planet in the most beautiful modern style at that time.
The Golden Record is meaningful in a way that it not only portrays the beauty of Mother Nature and evolution of human beings and their advancement in various fields, but also portrays the relationship between humankind and Mother Nature. The Golden Record portrays the beauty of the journey of life on the Pale Blue Dot.
When thinking about the differences between the early Earth and our world at present, I feel that the Golden Record as a whole highlights the fact that “life, uh, finds a way” and also implies the necessity to preserve and cherish the “Pale Blue Dot, the only home we have ever known”.
More Explorations, More Discoveries, More Surprises
The Voyagers may be very old but they are some of the best examples to prove that age is just a number after all! The Voyagers have been operating for around 43 years and 10 months at the time of this writing. While some instruments on the spacecraft are working, other instruments were turned off long ago to save power. Currently, the Cosmic Ray Subsystem (CRS), Magnetometer (MAG), Low-Energy Charged Particles (LECP), and Plasma Wave Subsystem (PWS) are still active for both the Voyagers. The Plasma Science (PLS) instrument is off for Voyager 1 while it is still working for Voyager 2. Imaging Science Subsystem (ISS), Infrared Interferometer Spectrometer and Radiometer (IRIS), Photopolarimeter Subsystem (PPS), Planetary Radio Astronomy (PRA), and the Ultraviolet Spectrometer (UVS) are not active anymore for both of them (again, they were turned off long ago to preserve power on the spacecraft).
The Voyager Mission has been a groundbreaking, truly productive, and incredibly ambitious endeavor that touched on practically every aspect of our solar system and planetary neighbours. The Voyagers’ findings are even today providing humanity with observations of truly uncharted territory, providing further information about the nature of energy and radiation in interstellar space.
Voyager Project Manager Suzanne Dodd (who is based at NASA’s Jet Propulsion Laboratory in Pasadena, California) has said, “It’s incredible that Voyagers’ instruments have proved so hardy. We’re proud they’ve withstood the test of time. The long lifetimes of the spacecraft mean we’re dealing with scenarios we never thought we’d encounter. We will continue to explore every option we have in order to keep the Voyagers doing the best science possible.”
According to Voyager Project Scientist Ed Stone (who is based at Caltech), both Voyager probes are exploring regions never before visited, so every day is a day of discovery, and this is going to keep surprising us with new insights about deep space.
So, Voyager 1 and its twin Voyager 2 seem to have many miles to go before they sleep. Do not go gentle into that good night, Voyagers!
A Personal Message for Voyager 1
The adventures of Voyager 1 can be framed into a story about a truly ambitious explorer — an explorer who, in spite of knowing that many problems and obstacles are out there and the places it is going to explore are all unknown to humankind, still continues the journey with full determination.
Initially, it explored areas surrounding our birthplace, sending pictures and other information to “family and friends” back here on Earth. On one Valentine’s Day, the explorer took some heart-touching photos — remembrances of its place of origin — and then sent the pictures back home.
Upon turning back to face the void of space before it, the explorer began its real journey, with a “heart” full of love for adventures and a “mind” full of love for challenges.
While exploring, the spacecraft keeps on discovering incredible things. While the power is slowly dwindling and the spacecraft will eventually lose the ability to “call” home, it still has a long journey ahead, travelling to places unknown to humankind — for me, this is what makes the journey so incredible and awe-inspiring.
This explorer carries a wonderful treasure — a box full of the symbols and knowledge of its birthplace, perhaps to give to something living in a yet-unknown place in future.
In honor of this explorer, I would like to leave the following personal message, with thanks and best wishes:
Dear Voyager 1,
Wishing you a very happy Valentine’s Day in advance! You are not just a bunch of instruments floating in deep space, you rather carry our hopes to the stars. You represent humanity in a distant and unknown place, unexplored by us yet. You have made us not just think big, but have driven us to think beyond. Keep exploring our dear friend, we will catch up to you one day. All the best for the explorations and new discoveries!
Now, Voyager, sail thou forth, to seek and find!
(An admirer from the Pale Blue Dot)
Arpita Saha is a Research Associate at the Blue Marble Space Institute of Science and a final year Bachelor of Science student pursuing Physics as Honours subject at Gokhale Memorial Girls’ College, affiliated to the University of Calcutta, India.