Pioneers 10 and 11
Back in 1973 when Pioneer 10 became the first spacecraft to fly through the asteroid belt, it was on the way to Jupiter. Pioneer 11 followed and visited both Jupiter and Saturn. Both spacecraft continued their missions as they traveled beyond the planets into deep space, returning data until they could no longer transmit. They are now both headed for interstellar space.
And since the spacecraft were going to the stars, why not include a message from humanity? Carl Sagan was enthusiastic about the idea. NASA agreed, but allowed only three weeks for its design. The result was the famous Pioneer plaque, which has a line drawing of two nude humans, and symbols - including a pulsar map - defining Earth's location.
The Golden Record
Planning for the Grand Tour of Voyager 1 and Voyager 2 was refined by data from the Pioneer missions. And since the Voyagers would also continue their missions into interstellar space, they could also take a message from Earth. A committee, headed by Carl Sagan at Cornell University, had six months to design it. The result was the Golden Record.
If you're going to send a message into deep space, both the carrier and the format must be robust. The committee chose a grooved record that played with a stylus. Since the neighborhood of the nearest star that Voyagers could meet was some forty thousand years away, vinyl wouldn't do. They used gold-plated copper with a protective aluminum case. It could last a billion years or more.
At the end of this article is the URL of a NASA website which has lists of the record's contents. But here are some highlights.
Etched on the cover is the location of Earth (using the same images as the pioneer plaque), and instructions for playing the record. Click for an annotated picture of the Golden Record cover.
There's also a feature we can't see in the picture: a tiny amount of uranium-238, which is radioactive. It decays (breaks down) over a known time into other elements. Analyzing the mixture of elements present would make it possible to calculate about how long the sample had been in space.
Scenes from Earth
There are 115 images showing such things as scientific and mathematical information, people and their activities, other living creatures, a book, buildings, landscapes and even radio telescopes. An additional image is a written greeting from Jimmy Carter, then President of the United States.
Sounds of Earth
One set of sounds is a mixture ranging from a kiss to thunder, and including a heartbeat, various modes of transport, animals and many others.
Speech and music are two of the most significant human sounds. There are greetings in 55 different languages. The committee tried to get a selection of languages that represented most of the world's people. (I didn't work out why five dead languages were included.)
The NASA site doesn't list them, but there is a greeting from the UN Secretary General, and further greetings and contents in several languages. But all of that is upstaged by a whale song, which is extended by mixing it as background to some of the human speech.
What did they decide was a representative ninety minutes of music? It is certainly eclectic. Bach is well-represented, sharing the disk with, among others, Peruvian panpipes, Azerbaijani bagpipes, a Navajo night chant, Chuck Berry and Louis Armstrong.
Who is the Golden Record's audience?
Ann Druyan's answer was that it was a message for an alien intelligence with the technology to intercept the spacecraft. Although admitting that this was unlikely to happen, nonetheless "we took our jobs seriously." The first possibility of such an encounter isn't for about forty thousand years.
Forty thousand years is a long time. Forty thousand years ago our ancestors were still over thirty thousand years away from settled agriculture and founding the first civilizations. Forty thousand years in the future perhaps our descendants will find a way to travel through deep space. Might they find the record? I wonder what they might make of it.
And there is a third potential audience. The multiplicity of languages wouldn't make sense to ET. Even if there could be a Rosetta Stone, the greetings are all different. Yet we on Earth recognize this diversity. In creating a positive view of our humanity and including the languages and music of diverse cultures, perhaps the Golden Record invites us to share in a dream.
President Carter's message read in part: "We hope someday, having solved the problems we face, to join a community of galactic civilizations. This record represents our hope and our determination, and our good will in a vast and awesome universe."
And we don't even have to chase the Voyagers into space. Murmurs of Earth is a book telling the Golden Record's story. It's out of print, but there are copies. A CD-ROM contains the record's contents, as does the Internet. For example, see Reference (3) below.
I imagine that whatever humanity's future is, in the 4020th century no trace will remain of the 20th century world that launched the Voyagers. Yet it's a pleasing thought that when all else is gone, two small silent spacecraft will still be carrying Bach and Berry, a kiss and a heartbeat to the distant stars.
(1) JPL/NASA, http://voyager.jpl.nasa.gov/spacecraft/goldenrec.html
(2) Megan Gambino "What Is on Voyager's Golden Record?" http://www.smithsonianmag.com/science-nature/What-Is-on-Voyagers-Golden-Record.html