35 years later - Voyager space explorers are still going to the stars
The year 1977 was an important one for music. Fleetwood Mac'sRumours and the Sex Pistols' Never Mind the Bollocks were released. Elvis left the building for the last time, dying at the age of only 42. But amid all this rock'n'roll history another less celebrated but far more significant album was quietly being made. Fashioned from copper rather than vinyl, and plated with gold for longevity, The Sounds Of Earth was compiled by the American astronomer Carl Sagan. It was a broader range of music than most of the other albums released that year, aiming to encapsulate 5,000 years of human culture; from an Australian Aborigine song and an Indian raga to Azerbaijani bagpipes, bamboo flutes, Bach, Beethoven and Chuck Berry.
Like any compilation album, each piece was carefully selected and its merit, to make the cut, hotly debated. But unlike most other records, only two copies were made. They were placed inside their aluminium album covers, complete with artwork in the form of a "clear", universally understandable, pictorial depiction of what they were and instructions for how to play them. A stylus was also included, to help any creatures that might chance upon them in the future to hear the music and other recordings. In a scene that would not have been out of place in Ridley Scott's recent Prometheus, they were then carefully bolted to the outside of the two Voyager spacecraft, by the last human beings ever to touch them.
The records sit on one face of each craft's 10-sided "chassis" or bus, above which sits the large, white 3.7-metre wide communications dish, which dominates the structure. Protruding, insect-like, from the craft are "limbs" and antennae. The radioisotope thermoelectric generators, which power the Voyagers in the darkest reaches of the outer solar system, stretch out to on one side, just below a proboscis-like, 13m-long magnetometer boom. Across the other side of the craft, another broad arm juts out. It carries Voyager's "eyes" – an array of cameras, spectrometers, particle detectors and other equipment.
The challenge for Nasa's Jet Propulsion Lab, which designed and constructed the Voyagers, was to build a craft that could survive in spacefor years. In the early 1970s, when the JPL team began the project, they'd never built a craft rated for longer than a few months of interplanetary travel. It was a big jump to create something that would reach the outer planets, and perhaps even farther. "At that point in time, that was a mind-blowing thought," says Voyager systems engineer John Casani. "How you build a spacecraft that can survive failures and still keep on chugging. We thought we could do it. Nobody else did!"
Half a decade of back-breaking building and testing followed, to create a craft which was up to the job. Read more:
