Editorial | Published:

Ambassador for Earth

Nature volume 443, page 606 (12 October 2006) | Download Citation


Is it time for SETI to reach out to the stars?

One of the strengths of the community involved in the search for extraterrestrial intelligence — known as SETI — is its imaginative capacity to take seriously things that most people dismiss out of hand.

The idea that the technologies of astronomy might go beyond allowing us new insights into the natural world, and provide us with a means of communion with alien creatures, is not entirely fanciful. Artificial phenomena, such as civilizations, will radiate energy as surely as natural ones do — and may even do so with the intention of communicating. We on Earth send a mish-mash of unnatural-looking radio waves out into the cosmos, not to mention a handful of neutrino beams.

But what if we were to add to that mish-mash some deliberate signals? If beamed tightly enough with the help of a radio-telescope antenna, even a low-power radio transmission can stand out from the general murmur to a star where it is aimed. This is the idea behind so-called 'active SETI', which some enthusiasts think is a way forward for the field. There are others who think that it poses small but real dangers, and thus needs to be discussed more broadly. But at a recent meeting of the International Academy of Astronautics SETI study group in Valencia, Spain, the mood of the gathering was with the enthusiasts.

It is easy to see the appeal of active SETI — it's right there in the adjective. Traditional SETI involves looking at vast amounts of radio data and finding nothing. Active SETI allows you to compose messages, pick target stars, develop new encodings, and so on. It can be used as an outreach tool — the European television channel Arte is currently encouraging people to send it messages specifically to be beamed to the stars as part of the celebrations surrounding the launch of Corot, a French satellite designed to detect planets around distant stars.

“It is not obvious that all extraterrestrial civilizations will be benign, or that contact with even a benign one would not have serious repercussions.”

At the same time, though, the risk posed by active SETI is real. It is not obvious that all extraterrestrial civilizations will be benign — or that contact with even a benign one would not have serious repercussions for people here on Earth. There is already an agreement within the SETI community that, should a signal from beyond be picked up, various bodies will discuss what response, if any, should be sent. Yet the Valencia meeting voted against trying to set up any processes for deliberating over the style or content of any spontaneous outgoing messages. In effect, anyone with a big enough dish can appoint themselves ambassador for Earth.

The chances of active SETI causing unpleasant outcomes with today's technology are in fact remote, as this would require us to lift ourselves over the threshold of detectability for an alien civilization that just happened to be orbiting the star at which the message was aimed, or to reveal some peculiar flaw in our psychological make-up that alien 'black-ops' specialists might start working out ways to exploit. Either way, the harm, even if done at the speed of light, would take decades to arrive.

These small risks should nonetheless be taken seriously. When technologies offer radical new possibilities, the people who have the privilege of playing with them also have a duty to consult widely about what those possibilities might mean. The SETI community should assess them in a discussion that is open and transparent enough for outsiders to listen to and, if so moved, to actively participate. Of course, consensus may not always be possible — but the sort of debate out of which consensus has a chance to emerge must now take place.

About this article

Publication history





    Further reading


    By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

    Newsletter Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing