How to Decode NASA’s Message to Aliens

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.

Relat­ed Con­tent: 

Carl Sagan Sent Music & Pho­tos Into Space So That Aliens Could Under­stand Human Civ­i­liza­tion (Even After We’re Gone)

NASA Lets You Down­load Free Posters Cel­e­brat­ing the 40th Anniver­sary of the Voy­ager Mis­sions

Carl Sagan Warns Con­gress about Cli­mate Change (1985)

Josh Jones is a writer and musi­cian based in Durham, NC. Fol­low him at @jdmagness

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