Carl Sagan

NASA / Wikipedia

Carl Sagan is the go-to guy for interstellar greeting cards. During the 1970s, he developed plaques for equipment that NASA thought had the potential of being discovered millions or billions of years in the future.

The most ambitious project was the golden records for the Voyager probes. Sagan was given the daunting task of assembling a guide to all things human. Something that would fit on a standard 12-inch record.

The Voyager crafts investigated Jupiter and Saturn before...