Albert A. Harrison
Albert A. Harrison, Ph.D., is Professor Emeritus in the Department of Psychology at the University of California, Davis. He is the author or co-author of over 100 papers in a wide range of journals, and his books on space exploration and astrobiology include Spacefaring: The Human Dimension; Living Aloft: Human Requirements for Extended Spaceflight (with Mary Connors and Faren Akins); After Contact: The Human Response to Extraterrestrial Life; Starstruck: Cosmic Visions in Science, Religion, and Folklore; and Civilizations Beyond Earth: Extraterrestrial Life and Society (with Douglas A. Vakoch).
He was a member of NASA’s Space Human Factors Engineering Science and Technology Working Group and the International Academy of Astronautics Space Architecture Study Group. In December 2003, Dr. Harrison was principal investigator of a NASA-sponsored conference on new directions in behavioral health, and he edited a special supplement on this topic for Aviation, Space & Environmental Medicine.
Ample evidence suggests that people seek to inform future generations about their lives, times, and accomplishments. Earth is sprinkled liberally with time capsules, monuments, tombstones, and other tributes to ego, achievement, and in some cases folly. Of such commemoratives Carl Sagan wrote, “For those who have something they consider worthwhile, communication to the future is an almost irresistible temptation.... In the best of cases it is an optimistic and far-seeing act; it expresses great hope for the future; it time-binds the human community; it gives us a perspective on the significance of our own actions at this moment in the long historical journey of our species.” Converging factors—including recognition that we may not be alone in the universe, realization that a major Near-Earth Object (NEO) impact or other terrestrial or cosmic catastrophe could spell the end of humankind, and emerging interstellar communication technologies—encourage us to reach out to new, unseen audiences.
In this paper I consider Active SETI, that is, attempts to make extraterrestrial civilizations aware of our own. (This pursuit is also known as METI, or messaging extraterrestrial intelligence.) Although a simple continuous-wave beacon might suffice, actual attempts have been more elaborate: encoding information in grids, plaques showing Earth’s location in the Milky Way, recordings of sights and sounds of Earth, eerie electronic music, representations of human DNA, and personal letters. In his definitive history of time capsules, William E. Jarvis defines space-time capsules as slices of culture, frozen in time and sent beyond Earth. These include spacecraft that bear greetings from humankind and microwave transmissions that transcend physical containers and carry time capsule–like messages at the speed of light to distant stars. As in the great time capsules of the20th century, space-time capsules are deliberate efforts to communicate with audiences that differ, perhaps in radical ways, from the people who assembled the contents. As is true for even the most ambitious terrestrial time capsules, we really do not know if and when a space-time capsule will be retrieved. If the recipient is many light-years away, discovery may occur long after our society has ground to a halt. Whether they receive one of our space-time capsules—or we receive one of theirs—it could be a message from ancient history.