Thursday, October 12, 2000 9:30 p.m.

SETI@Arecibo Diaries

SECOND ENTRY - SCANNING FOR SIGNALS: I dont imagine that Columbus spent a lot of time at the bow of his ship, squinting at the horizon for sign of land. He left that tedious job to some miserable hireling, sent into the rigging. Meet the modern day hireling: The System. READ MORE .

THIRD ENTRY - THE ART OF OBSERVING: Its 6:00 p.m., and alreadydark outside. Weve deliberately chosen to conduct our search at night to avoidthe problem caused by signals passing too near the Sun. Charged particles from Sol can turn a narrow-band signal from an easy-to-find pure tone to a difficult-to-uncover buzz. So our hunt for ET is nocturnal. READ MORE .

"So, do you really, really think there are aliens out there?"

It was a question Id heard often, but I tried to smile. "Yes, I do" I replied, adjusting myself in the tortuous accommodation known as a coach seat. "I wouldnt be on this plane otherwise."

It takes about a day to travel from California to the worlds largest antenna in Arecibo, Puerto Rico. Theres the flight across Americas belly to Miami, and then another two hours of flying to cross the top of the Caribbean. The last hour and a half is spent driving along the northern coast of Puerto Rico, ultimately crawling inland through the bumpy hills that lead to the telescope.

The trip is long, but necessary. The evidence for extraterrestrials (if it exists at all) is undoubtedly washing over Earth everywhere, and all the time. But our SETI Institute research team makes the trip to Puerto Rico twice a year because this remote patch of hilly real estate is home to a unique instrument. The Arecibo telescope is so sensitive, it could pick up a cell phone a half-billion miles away.

We dont look for cell phones, of course. Our intention is to find a beacon either accidentally or deliberately pointed our way a radio signal that would tell us were not alone in the galaxy.

Project Phoenix is a systematic search of nearby star systems, with emphasis on those that seem to be most like the Sun. For hours at a time, the 1,000-foot (305-meter) Arecibo antenna keeps its gaze fixed on a single star, its motors grinding as it compensates for Earths rotation.

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I haul my carry-ons through the labyrinthine Miami airport, looking for the connecting flight to San Juan. Mostly, my thoughts are on logistics. But a simple question from an airline seatmate can still bring me up short can still remind me in a direct way of what this trip is really about. Its exploration, after all. Project Phoenix has examined 500 star systems so far without finding an alien signal. While Im at the telescope, well search several dozen more.

So its another 10 days sail, and maybe well only blow through more empty ocean. But the chance for surprise is always there. I didnt lie to that guy on the plane. I didnt try to shine him on with professional optimism. There are 5 million possible patches of sky to aim at with this telescope. Our receivers sift between 1 billion and 2 billion radio channels for each patch we observe. Somewhere in that mob of possibilities, there are Im sure signals awaiting our discovery. With the right combination of position and frequency, we could tune and detect the subtle dance of electromagnetic waves set in motion years ago by unseen and unknown intelligence.

Its a stunning thought, and one so imposing that I automatically shunt it from my mind and concentrate on finding a bit of overhead bin space. Five hours from now, the adventure will begin.