This article was originally published on Conversation. (opens in a new tab) The publication posted an article on Space.com Expert Voices: Evaluation and Understanding.
Alice Gorman (opens in a new tab)Associate Professor of Archeology and Space Studies, Flinders University
On August 20, 1977, 45 years ago, an extraordinary spacecraft left this planet and set off on an incredible journey. Voyager 2 was going to show us, for the first time, what the outer planets of the solar system look like close-up. It was like sending a fly to New York and asking it to report back.
Voyager 1 was launched after Voyager 2 on September 5. Attached to the side of each Voyager was a Golden Disc with greetings, sounds, images and music from Earth.
The spacecraft were more or less identical, but had different trajectories and scientific instruments. So far, both have flown by Jupiter and Saturn, then Voyager 1 sped off into interstellar space. Voyager 2 was delayed to make a one-off visit to the ice giants, Uranus and Neptune.
Gallery: Celebrate Voyager’s 45th Anniversary with These Amazing Images of Our Solar System
Colorful worlds
Upon arriving at Uranus in 1986, Voyager 2 detected pale blue-green clouds and a possible “dark spot,” which was later confirmed Hubble Space Telescope. The unexpected happened magnetic field (opens in a new tab), which dragged a corkscrew trail of particles behind the planet as it rolled in its orbit. ten new moon (opens in a new tab) were discovered, including gray, cratered ones Washer (opens in a new tab)and two new charcoal black rings.
Three years later, Voyager 2 reached Neptune and sent home pictures of blue and cobalt clouds swirled by winds of up to 11,000 miles per hour (18,000 kilometers per hour). The slate-colored “great dark spot” represented a storm the diameter of Earth. the biggest month Tritonwas pink with methane ice and sputtering geysers of frozen nitrogen (opens in a new tab).
Since then, the spacecraft has not returned.
Messages to the future
Even more than these glimpses of distant icy planets, what excites people about the Voyager mission is the famous Golden records (opens in a new tab). A committee headed by a visionary astronomer Carl Sagan worked for more than a year (opens in a new tab) collect materials to depict the planet Earth. The music gets the most attention as a “mix for the universe,” but that’s not the only thing that stands out.
One of the sounds of the earth is this production of stone tools (opens in a new tab), or “knock”. It is the most durable technology invented by humans and their ancestors since about 3 million years ago (opens in a new tab) so to this day. For most of human existence, the sound of stone striking stone to detach sharp-edged cutting scales was heard daily in every human settlement.
On the recording, you can hear the impact of a stone against the background of heartbeats.
In one of the 116 images, a black scientist in a lab coat leans over a microscope, tiered earrings gracefully falling from her ears. The earrings were a point of contention: would a would-be extraterrestrial viewer recognize the term “jewellery”? It was hoped that this image together with photomicrograph (opens in a new tab) of dividing cells in Figure 17 will help viewers understand that the science of microscopy was known on our planet.
People recorded messages in 55 languages (opens in a new tab). Some of them are ancient languages, for example acadian (opens in a new tab) and Hittite, not heard on Earth for thousands of years. The most frequently used words are “hello”, “peace” and “friend”. Janet Sternberg’s Portuguese greeting reads simply, “Peace and happiness to all.”
A long goodbye
Finally, in 2018 Voyager 2 joined Voyager 1 beyond the heliopause, where the solar wind is deflected by the wind from interstellar space. Our galaxy is 100,000 people light years across, and Voyager 2 is now just under 18 light-hours from Earth.
Both spacecraft send interplanetary signals to three antennas that are still listening: Tidbinbill (opens in a new tab)Goldstone and Madrid.
Before they can truly leave, the Voyagers will have to travel through Oort clouda vast dark sphere of icy objects surrounding the solar system for another 20,000 years.
Slow down, Voyager 2. systems shut down (opens in a new tab) to retain power as long as possible. But somewhere in the 2030s, they will not be left.
Even after Voyager 2 stops transmitting, it won’t be completely dead. The half-life of plutonium-238 in its nuclear power source is 87.7 years, while a small fraction coating with uranium-238 (opens in a new tab) on the Golden Record is 4.5 billion years. Both elements slowly turn into lead.
Radioactive transmutation of elements is a kind of reverse alchemy on a cosmic timescale. This process of becoming will not end until there is nothing left on Voyager 2 to transform.
Cultural significance
The constant bombardment of dust particles will gradually erode Voyager 2’s surfaces, likely at a faster rate than Voyager 1 because it travels through different regions of interstellar space. Still, his Gold record should be there at least partially legible after 5 billion years.
The land depicted in the Golden Records will likely be unrecognizable even 100 years from now. The spacecraft and the records will remain as a fragmentary archaeological record for the unknowable future.
While the Golden Records are endlessly fascinating, Voyager’s true cultural significance lies in its location. The spaceship is a boundary marker that shows the physical extent of human interaction with the universe.
If the Voyagers stop transmitting, it will be like losing your senses. Telescopes can only show us so much: there’s no substitute for being there.
Who will follow their path?
This article is reprinted from Conversation (opens in a new tab) under a Creative Commons license. To read original article.
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