A graphic message sent into space by the Arecibo radio telescope in the 1970s.

A graphic message sent into space by the Arecibo radio telescope in the 1970s.

Arne Nordmann/Creative Commons

Researchers call for interstellar messages to alien civilizations

SAN JOSE, CALIFORNIA—Is it time to send deliberate messages to the stars, in the hopes of reaching alien civilizations? Advocates in the Search for Extraterrestrial Intelligence (SETI) say that moment is long overdue. But other researchers want to take a more cautious approach and seek an international consensus before outing Earth to the rest of the universe. Scientists in both camps faced off today at a debate held at a meeting of AAAS (which publishes Science) here.

Douglas Vakoch, the director of interstellar message composition at the SETI Institute in Mountain View, California, doesn’t dismiss the need to consider ethical or political issues, but says that it will be tough to achieve a consensus. “It’s ‘either-or’ thinking,” he says. “Either we have international discussion, or we transmit. We should be doing both.” But David Brin, an astrophysicist and science fiction author here, says that Earth’s relative radio quietude should not be changed so radically, so quickly. “If you’re going to transform one of the major characteristics … of our planet, we’ve learned that small groups shouldn’t do that peremptorily.”

Since the SETI movement began in the 1960s, it has mostly involved using radio telescopes to listen to bands in the electromagnetic spectrum for something out of the ordinary. In contrast, instances of active SETI, also called Messaging Extraterrestrial Intelligence, or METI—beaming deliberate messages to the heavens—have been much rarer. In 1974, a radio message was broadcast from the Arecibo telescope in Puerto Rico toward a cluster of stars 25,000 light-years away. Brin says there have been other “stunts.” In 2008, for instance, the tortilla chip company Doritos sent an advertisement from a radar station in Norway to a potentially habitable star system 42 light-years away.

Advocates for active SETI say that keen-eared aliens could already pick up some of Earth’s ambient transmissions. Current radio and TV transmissions could be heard only a few light-years away with the current radio telescope technology on Earth, but Vakoch says that an advanced civilization would have far more developed techniques for listening. Brin says this is the “barn door excuse” and adds that many active SETI techniques would send out focused, powerful messages that would travel many times farther than the day-to-day transmissions from Earth. He views active SETI messages as cosmic pollution, rather than exploration. Although he’s not worried about alien invasions, he thinks the assumption of benevolence—or even the existence of aliens—is overstated.

Vakoch says the SETI Institute has no imminent plans to start transmitting messages, but he finds that other organizations are not taking the lead in holding international discussions on the issue. He says that one efficient way of transmitting messages would be by adding messages in the regular course of doing planetary science. When the Arecibo radar is used to study asteroids, for instance, messages could be sent to stars near the line of sight of the asteroid without much additional effort. What would these messages include? Seth Shostak, an astronomer at the SETI Institute, wants to beam the entire Internet. Vakoch would prefer something humble that conveys the challenges that humanity faces.

Brin doesn’t see resolution to the passionate debate anytime soon. “It’s an area where opinion rules, and everyone has a fierce opinion.”

Check out our full coverage of the AAAS annual meeting.

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