When NASA spent close to a billion dollars on the Voyager program, launching a pair of probes from Cape Canaveral in 1977, its primary purpose was not to find intelligent extra-terrestrial life. The program grew out of ambitions for a “Grand Tour”: four robotic probes that would visit all the planets in the outer solar system, taking advantage of a 175-year alignment of Jupiter and Saturn. A downsized version produced Voyager 1 and 2, each craft “a miniature marvel,” writes the Attic. “Weighing less than a Volkswagen, each had 65,000 parts. Six thrusters powered by plutonium. Three gyroscopes. Assorted instruments to measure gravity, radiation, magnetic fields, and more. Design and assembly took years.”
Since reaching Jupiter in 1979, the two probes have sent back astonishing images from the great gas giants and the very edges of the solar system. “By 2030, Voyager 1 and 2 will cease communications for good,” says Cory Zapatka in the Verge Science video above, “and while they won’t be able to beam information back to Earth, they’re going to continue sailing through space at almost 60,000 kilometers per hour,” reaching interstellar unknowns their makers will never see. Voyager 1 was only supposed to last 10 years. In 2012, it left the solar system, to drift, along with its twin, “endlessly among the stars of our galaxy,” Timothy Ferris writes in The New Yorker, “unless someone or something encounters them someday.”
As deep space detritus, the probes will make excellent carriers for an interstellar message in a bottle, the Voyager team reasoned. The idea prompted the creation of the Golden Record, an LP fitted to each probe containing a message from humanity to the cosmos. “Etched in copper, plated with gold, and sealed in aluminum cases, the records are expected to remain intelligible for more than a billion years, making them the longest-lasting objects ever crafted by human hands.” Produced by Ferris and overseen by Carl Sagan and a team including his future wife, Ann Druyan, the Golden Record includes the work of Mozart, Chuck Berry, folk music from around the world, the sounds of waves and whales, and one of the most universal of human sounds, laughter (likely that of Sagan himself).
The Golden Record also includes 115 images, etched into its very surface. No, they are not digital files. “There are no jpegs or tifs included on it,” says Zapatka. After all, “The Voyager’s computer systems were only 69 kilobytes large, barely enough for one image, let alone 115.” These are analog still photographs and diagrams that must be reconstructed with mathematical formulae extracted from electronic tones. The process starts with the diagrams on the record’s cover — simple icons that contain an incredible density of information. We begin with two circles joined by a line. They are hydrogen atoms, the most plentiful gas in the universe, undergoing a change that occurs spontaneously once every 10 million years.
During this rare occurrence, the hydrogen atoms emit energy at wavelengths of 21 centimeters. This measurement is used as “a constant for all the other symbols on the record.” That’s an awful lot of background knowledge required to decipher what look to the scientifically untrained eye like a pair of tiny eyes behind a pair of odd eyeglasses. But for spacefaring aliens, “how hard could that be?” says Bill Nye above in an abridged description of how to decode the Golden Record. We may never, in a billion years, know if any extra-terrestrial species ever finds the record and makes the attempt. But the Golden Record has become as much an object of fascination for humans as it is a greeting from Earth to the galaxy. Learn more from NASA here about the images encoded on the Golden Record and order your own reproduction (on LP or CD) here.