* This week in 1977, the spacecraft Voyager 2 was launched. Attached to it was a copy of the Voyager Golden Record, a gold-plated LP with an aluminium cover. It contained a selection of music and images chosen by a committee chaired by Carl Sagan.
* While some of the music was quickly agreed (Beethoven's Fifth, Chuck Berry's "Johnny B Goode"), other selections proved problematic. All four Beatles approved the use of "Here Comes the Sun", but copyright made it "too murky to risk". One ethnomusicologist insisted on the inclusion of a raga called "Jaat Kahan Ho", but no one could locate a copy; one was eventually found just before deadline in an Indian-owned appliance store on New York's Lexington Avenue.
* Sagan tried to get the UN's help to record the word "Hello" in 55 languages, but faced innumerable bureaucratic problems. In addition, some UN delegates became over-eloquent during recording. The Nigerian was reported to have said: "As you probably know, my country is situated on the west coast of the continent of Africa, a land mass more or less in the shape of a question mark in the centre of our planet."
* A photograph of a naked couple was to have been included. However, the drawing of a naked couple that accompanied the Pioneer 10 space probe in 1972 had created such a public fuss that Nasa vetoed Sagan's plan; it was replaced with an annotated silhouette instead.
* The knottiest problem: how do you teach an alien how to play a record? Nasa went with a diagrammatic Ikea approach on the aluminium cover, using a binary code to define "the proper speed to turn the record expressed in 0.70 x 10-9 seconds, the time period associated with the fundamental transition of the hydrogen atom." Good luck with that, aliens!