Contact: What Happens if a Signal is Found

If youchanced to be among the handful of visitors wandering the lava-strewn landscapeof northeastern California on July 18, 2006, you might have seen the preamble to what could be a verygiant leap for mankind. In the dusty pastures edging the town of Hat Creek, in the northern shadow of moldering Mt. Lassen, tenantennas revved their motors, and panned the sky. They were making their debutas the first working elements of the Allen Telescope Array.

This newinstrument which--when completed--will brandish 350 antennas, can speed up thesearch for signals from other societies by hundreds of times and more. Compared to earlier efforts, it will turn SETI on its metal ear. We're nottalking about the difference between a Lexus and a Toyota; we're talking about the differencebetween a Lexus and an oxcart.

In the nexttwo dozen years, the Allen Telescope Array will parse the nearest thousandlight-years of space. If there are other occupants of this galacticneighborhood, we could turn up a signal.

But thenwhat? Would the discovery be put under wraps, either voluntarily or bygovernment edict? If we found a signal, would you know?

This isamong the most commonly asked questions of SETI: what happens in case of adetection. Conditioned by television, movies, and a penchant for expectingconspiracy, a lot of people think that the truth would not be out there. Theybelieve it entirely reasonable to expect that the military, worried that thealiens will threaten the planet, would surround the telescope with chain link,and redirect the data stream to the Pentagon. Another common assumption isthat the government, figuring that the citizenry will lose its cool, stampedethe streets, and provoke a seismic collapse of polite society, will keep thediscovery under wraps. Some even venture the thought that SETI scientists, forunspecified (and hard to imagine) reasons, would deprive themselves of futurefunding and the Nobel Prize by squirreling away their find.

Not achance. And the reason I say that is, first and foremost, because the handfulof researchers doing SETI experiments are intensely keen to find treasure, notto bury it. But even if you don't respect the integrity of the scientists,even if you think these dedicated folks have motives that are secret andsuspect, then you should at least look at the process. Frankly, secrecy isruled out by how the experiment is done.

What happens when a signalcomes in

Now I'vewritten about this matter on these web pages before, but not in the last fiveyears. So allow me to refresh memories (if you have them) by noting thatthere's a protocol that outlines the activities to be followed by anyindividual or organization that finds an extraterrestrial signal. In short,this document, constructed by an international group of SETI scientists, boilsdown to the following action plan in case of a suspected transmission from analien world:

First, thediscoverers should verify that the signal is really extraterrestrial andartificial, not man-made interference or natural, cosmic static. Having doneso, those who made the discovery are to notify all the other signatories to thedocument so that they can independently proceed to check it. They should alsoinform national authorities. Next on the list of those notified are all theworld's astronomers, so that every available telescope can be used to study thesource of the signal. And then there's this, verbatim from the protocol;namely that the detection "should be disseminated promptly, openly, and widelythrough scientific channels and public media..."

Soundsstraightforward, right? And it is. However, this protocol assumes an orderlyprocession of events, with detection quickly followed by verification, which isthen followed by spreading the news.

Well, reallife is messy, as Pigpen knew. The disorder arises from the fact that thehighly sensitive antennas used by SETI, coupled to digital receivers monitoringa hundred million channels or more, turn up signals all the time. When we wereusing the Arecibo radio telescope in Puerto Rico, there were detections falling outof the receivers every few seconds. This is not like in the movies, when acontrol-room oscilloscope suddenly goes from flatline to a profile resembling asharpened pencil point, encouraging bored-looking scientists to wake up andstart screaming. In reality, sifting through all those signals to see if anyhave the characteristics of an extraterrestrial source takes a longtime. It's days before you're sure, or at least reasonably sure.

That's avery important, and currently unavoidable fact. Another relevant circumstanceis that SETI is done in the open. For example, at every radio telescope we'veever used, there are observatory (not SETI) personnel in the control room 24/7,not to mention local visitors and a raft of other interested parties (JimiHendrix's sister, several Silicon Valley executives, Isaac Asimov's daughter,and Miss Puerto Rico are among many who toured the control room at Areciboduring Project Phoenix observations). If we're looking at an interestingsignal--one that's passing the tests that can separate the local interference from an extraterrestrial transmission--then a lot of people know, even beforewe call up someone in another state or another country to verify its reality. The excitement begins to build long before the detection is confirmed.

Whathappens thereafter departs from the protocol, because the media start calling. When, in June of 1997, we had a suspicious signal on our computer screens, a NewYork Times science reporter was on the phone with me within hours. At thesame time, a TV crew was, by chance, in the control room of the telescope. Asit turned out, that signal, which slipped by our usual software filters due toan equipment malfunction, was from a European research satellite (SOHO) whosetelemetry was bouncing around the steelwork of the radio telescope.

It allmeans the following: you will be media-blasted about a possible detection daysbefore the people who find it are certain it's for real. (This may pose adilemma for SETI Institute scientists, who always keep a bottle of champagne atthe observing site. When do we pop the cork?) There's also the near-certainconsequence that there will be false alarms for SETI experiments in the future,as reporters describe interesting signals which, upon closer inspection, turnout to be telecommunication satellites, airport radar, or just electronicnoise.

Becauseverifying a signal is slow and the media are fast, there will be days ofuncertainty for any newly detected candidate signal. Consequently, somemembers of the SETI community have devised an index of a signal's credibility,known as the Rio Scale. This scale evaluates with a numeric grade any claim ofa detection, as judged by SETI researchers themselves. The researchers awardtheir grade on the basis of the signal's technical characteristics. Sure, theRio Scale is not a perfect gauge; it's not magic. But it is expertopinion, and should help the interested public by making manifest the judgmentof an international group of SETI practitioners.

In the end,of course, and like all good science, a real detection will be confirmed by awide range of observations, involving observers from many countries during thecourse of days or weeks. Facts are, the first discovery of a signal from analien world will break into the world's consciousness in a haphazard, messyfashion. The news won't be crisp and well-defined. But it will be very, veryexciting.

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Seth Shostak
Senior Astronomer, SETI Institute

Seth Shostak is an astronomer at the SETI (Search for Extraterrestrial Intelligence) Institute in Mountain View, California, who places a high priority on communicating science to the public. In addition to his many academic papers, Seth has published hundreds of popular science articles, and not just for; he makes regular contributions to NBC News MACH, for example. Seth has also co-authored a college textbook on astrobiology and written three popular science books on SETI, including "Confessions of an Alien Hunter" (National Geographic, 2009). In addition, Seth ahosts the SETI Institute's weekly radio show, "Big Picture Science."