There is something intrinsically romantic about a lone spacecraft drifting through the infinite horizon. It valiantly continues to communicate, even if its time is finite. In February this year, travelling at 61,197 km/h (38,026 mph) relative to the sun, Voyager 1 crossed the 25-billion-kilometre mark (about 15.6 billion miles) from Earth. Radio signals now take about 22.5 hours one way. It is the fourth fastest and furthest-travelled human-made object.
Launched on 5th September 1977, Voyager 1’s mission was to study the boundaries of the heliosphere. It also aimed to begin exploring interstellar space. On 25th August 2012, it became the first spacecraft to cross the heliopause. This theoretical boundary is where the sun’s solar wind can no longer repel stellar winds from surrounding stars. Voyager confirmed this by detecting a surge in cosmic rays and a sharp drop in solar protons.
On its journey, the probe made flybys of Jupiter, Saturn, and Titan – Saturn’s largest moon. NASA chose Titan over Pluto due to its substantial atmosphere. Voyager 1 studied magnetic fields, weather systems, and returned the first detailed images of the solar system’s gas giants.
But perhaps its most enduring legacy is a photograph. On 14th February 1990, from six billion kilometres away, Voyager 1 turned its camera back towards Earth. Just 34 minutes before its camera was switched off forever, it captured a speck of light – our planet. That “pale blue dot” remains one of the most poignant images in the history of space exploration.
From the left: “Pale Blue Dot”, the iconic picture by Voyager 1 showing Earth as a bright speck within the sunbeam. © NASA JPL-Caltech; Cosmos host Carl Sagan with the Voyager module, 1980, © Courtesy of PBS.
The image was part of a mission proposal by Carl Sagan. It later inspired his book Pale Blue Dot: A Vision of the Human Future in Space. He wrote: “That’s here. That’s home. That’s us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives… on a mote of dust suspended in a sunbeam.” He added “There is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly with one another. Also, to preserve and cherish the pale blue dot, the only home we’ve ever known.”
As Voyager 1 sailed onwards, it was carried by solar winds and gravity assists from Jupiter, Saturn, and Titan. NASA worked to extend its battery life as far as possible. The probe is expected to keep returning scientific data until at least the end of this year. It might possibly continue up to 2030. Its generators are likely to supply enough electricity for engineering data until 2036.
From the left: Voyager 1 aboard the Titan III Centaur rocket lifted off on 5th September 1977. © NASA; Voyager’s Golden Record, a 12-inch gold-plated phonograph record with images and sounds from Earth. © NASA.
After that, this lonely cosmic explorer will drift further into space. On board is a message from Earth—a golden record greeting for any prospective extraterrestrial life, light years from now. This gold-plated audio-visual disc was created under the direction of Carl Sagan and science author Timothy Ferris. It includes photos of Earth and its lifeforms. The disc also contains scientific data and spoken greetings from figures such as UN Secretary-General Kurt Waldheim and U.S. President Jimmy Carter. It has a medley – “Sounds of Earth” – featuring whales, a baby crying, waves on a shore, and music from various cultures and eras. The project was meant to portray the richness of life on Earth. It serves as a testament to human creativity and the desire to connect with the cosmos.
On 29th August 1979, Voyager II launched to explore the solar system’s ice giants. After sending back stunning images of Uranus and Neptune, it entered interstellar space on 5th November 2018. In a real sense, the Voyagers are our cosmic messengers. We may beam signals from telescopes and listen for replies. Yet the idea of a physical envoy carrying a golden greeting is far more tangible.
The two Christopher Columbuses of space exploration captured the human imagination and entered popular culture. This is evident in Star Trek: The Motion Picture (1979) where Voyager falls through a black hole, ends up among sentient machines, and is sent back to its creator. It becomes self-aware in the process and threatens Earth for answers about its origins to the film Starman, the TV series The X-Files and even the cover of The Moody Blues album Long Distance Voyager.
Voyager 1 images of the two gas giants in our solar system: Jupiter (left) and Saturn (right). © NASA.
Sagan’s work on Voyager shaped his groundbreaking TV series Cosmos. The episodes featured mission footage. This included the famous “pale blue dot” image, and the spaceship in the opening credits – hurtling through the universe to Vangelis’ music – was inspired by Voyager’s endless journey into the unknown.
Voyager 1 is expected to reach the Oort Cloud in 300 years. This is a vast, hypothetical shell of icy objects surrounding our solar system. It will then take 30,000 more to cross it. Although not headed toward any particular star, in 40,000 years it will pass by the constellation Camelopardalis which is about 17.1 light-years from Earth. No one knows what lies out there. However, NASA suggests the Voyagers are destined – perhaps eternally – to wander the Milky Way. If found by intelligent extraterrestrial life, what might they make of our interstellar messenger?
This is a reduced version of the full feature about the Voyagers in the summer issue of I-M Inquisitive Minds. Secure your copy, HERE.
Author: Andrew Hildreth
If you are interested in space exploration, you may enjoy reading about the next mission to the moon, which will see the first woman stepping on it… dressed in Prada.
Lead image: Artist concept of NASA Voyager 1 spacecraft with its antenna pointing to Earth. © NASA JPL
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