The Voyager spacecraft will be the third and fourth human artifacts toescape entirely from the solar system. Pioneers 10 and 11, which precededVoyager in outstripping the gravitational attraction of the Sun, both carrieda graphic message in the form of a 6- by 9-inch gold anodized plaquebolted to the spacecraft's main frame.

On the plaque a man and woman stand before an outline of the spacecraft.The man's hand is raised in a gesture of good will. The physicalmakeup of the man and woman were determined from results of a computerizedanalysis of the average person in our civilization.

The key to translating the plaque lies in understanding the breakdownof the most common element in the universe - hydrogen. This elementis illustrated in the left-hand corner of the plaque in schematic formshowing the hyperfine transition of neutral atomic hydrogen. Anyone froma scientifically educated civilization having enough knowledge of hydrogenwould be able to translate the message. The plaque was designed by Dr.Carl Sagan and Dr. Frank Drake and drawn by Linda Salzman Sagan.

With this example before them, NASA placed a more ambitious messageaboard Voyager 1 and 2-a kind of time capsule, intended to communicatea story of our world to extraterrestrials. The Voyager message is carriedby a phonograph record-a 12-inch gold-plated copper disk containing soundsand images selected to portray the diversity of life and cultureon Earth. The contents of the record were selected for NASA by a committeechaired by Carl Sagan of Cornell University. Dr. Sagan and his associatesassembled 115 images and a variety of natural sounds, such as those madeby surf, wind and thunder, birds, whales, and other animals. To this theyadded musical selections form different cultures and eras, and spoken greetingsfrom Earth-people in fifty-five languages, and printed messaged from PresidentCarter and U.N. Secretary General Waldheim. Each record is encased in aprotective aluminum jacket, together with a cartridge and a needle. Instructions,in symbolic language, explain the origin of the spacecraft and indicatehow the record is to be played. The 115 images are encoded in analogform. The remainder of the record is in audio, designed to be played at16-2/3 revolutions per second. It contains the spoken greetings,beginning with Akkadian, which was spoken in Sumer about six thousand yearsago, and ending with Wu, a modern Chinese dialect. Following the sectionon the sounds of Earth, there is an eclectic 90-minute selectionof music, including both Eastern and Western classics and a varietyof ethnic music. Once the Voyager spacecraft leave the solar system (by1990, both will be beyond the orbit of Pluto), they will find themselvesin empty space. It will be forty thousand years before they make a closeapproach to any other planetary system. As Carl Sagan has noted, "The spacecraftwill be encountered and the record played only if there are advanced spacefaringcivilizations in interstellar space. But the launching of this bottleinto the cosmic ocean says something very hopeful about life onthis planet."