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

This new instrument which--when completed--will brandish 350 antennas, can speed up the search 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 not talking about the difference between a Lexus and a Toyota; we're talking about the difference between a Lexus and an oxcart.

In the next two dozen years, the Allen Telescope Array will parse the nearest thousand light-years of space. If there are other occupants of this galactic neighborhood, we could turn up a signal.

But then what? Would the discovery be put under wraps, either voluntarily or by government edict? If we found a signal, would you know?

This is among the most commonly asked questions of SETI: what happens in case of a detection. Conditioned by television, movies, and a penchant for expecting conspiracy, a lot of people think that the truth would not be out there. They believe it entirely reasonable to expect that the military, worried that the aliens will threaten the planet, would surround the telescope with chain link, and redirect the data stream to the Pentagon. Another common assumption is that the government, figuring that the citizenry will lose its cool, stampede the streets, and provoke a seismic collapse of polite society, will keep the discovery under wraps. Some even venture the thought that SETI scientists, for unspecified (and hard to imagine) reasons, would deprive themselves of future funding and the Nobel Prize by squirreling away their find.

Not a chance. And the reason I say that is, first and foremost, because the handful of researchers doing SETI experiments are intensely keen to find treasure, not to 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 and suspect, then you should at least look at the process. Frankly, secrecy is ruled out by how the experiment is done.

What happens when a signal comes in

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

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

Sounds straightforward, right? And it is. However, this protocol assumes an orderly procession of events, with detection quickly followed by verification, which is then followed by spreading the news.

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

That's a very important, and currently unavoidable fact. Another relevant circumstance is that SETI is done in the open. For example, at every radio telescope we've ever 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 (Jimi Hendrix's sister, several Silicon Valley executives, Isaac Asimov's daughter, and Miss Puerto Rico are among many who toured the control room at Arecibo during Project Phoenix observations). If we're looking at an interesting signal--one that's passing the tests that can separate the local interference from an extraterrestrial transmission--then a lot of people know, even before we call up someone in another state or another country to verify its reality. The excitement begins to build long before the detection is confirmed.

What happens 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 New York Times science reporter was on the phone with me within hours. At the same time, a TV crew was, by chance, in the control room of the telescope. As it turned out, that signal, which slipped by our usual software filters due to an equipment malfunction, was from a European research satellite (SOHO) whose telemetry was bouncing around the steelwork of the radio telescope.

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

Because verifying a signal is slow and the media are fast, there will be days of uncertainty for any newly detected candidate signal. Consequently, some members 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 of a detection, as judged by SETI researchers themselves. The researchers award their grade on the basis of the signal's technical characteristics. Sure, the Rio Scale is not a perfect gauge; it's not magic. But it is expert opinion, and should help the interested public by making manifest the judgment of an international group of SETI practitioners.

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

• Learn More About SETI
• Just the Facts: Three SETI Myths
• Mars Analog on Earth: Taking a Trek in the Outback
• VIDEO: Figuring Out the Odds of ET Existing
• VIDEO: Reflections of Fermi's Paradox
• VIDEO: Listening for Life