THIRTY years ago today, the Voyager 1 space probe — a one-ton robotic craft whose long antennas make it look rather like a spider the size of a school bus — was launched from Cape Canaveral...If all continues to go well, Voyager should pierce the heliosphere’s outer skin by around 2015. It will then depart into the void of interstellar space, where it is destined to wander among the stars forever.

Mindful of this mind-boggling fact, the astronomers Carl Sagan and Frank Drake persuaded NASA to attach a gold-plated phonograph record to each of the Voyager spacecraft. Containing photographs, natural sounds of Earth and 90 minutes of music from all over our world, the record was intended to preserve something of human culture beyond what an intelligent extraterrestrial, encountering the craft at some far-distant time and place, might infer from the spacecraft itself.

The information etched into the grooves of the Voyager record is expected to last at least one billion years. That’s a long time: A billion years ago, life on Earth was first venturing forth from the seas.