Arecibo Chronicle



Sometimes I feel like an ant.

Actually, that syntax implies that I might have a hankering for some chocolate-covered formicidae, but that’s not right. What I mean to say is that sometimes — usually after dinner, it seems — my mind zooms back in hope of seeing the big picture: trying to get the establishing shot’ on life, SETI, and just what the heck we’re doing here in the lush foliage of Puerto Rico. And the first jarring revelation afforded by this wide-angle view is that we’re just ants.


Arecibo Observatory
The Arecibo radio telescope is currently the largest single-dish telescope in the world used in radio astronomy. In 1974, Arecibo was used to broadcast a message from Earth to the globular star cluster M13.
Credit: NAIC – Arecibo Observatory, David Parker / Science Photo Library

There have been ten thousand generations of Homo sapiens before us. Since it’s a fairly good rule of science to assume that anything you observe is typical (until shown otherwise), there may be ten thousand generations to follow.

This is like the ants in my backyard. Those segmented little beasts are only one rank of marchers in a parade of time that stretches dauntingly backwards and forwards. Sure, they think they’re special. They eagerly do their ant thing,’ hauling foodstuffs back to the nest in long, organized lines. But really, they’re no more special than their great-great-great-great (put in one thousand "greats" here) grand-ants, or the countless ants to follow.

It seems pretty analogous to the human condition, but not entirely. For SETI, we figure our generation really is special. Ours is the generation that — either at this observatory or some other — will break step with the parade and finally shatter the bubble of isolation that has enclosed life on this planet for 3.5 billion years.

But are these thoughts merely wishful thinking, or worse, just hubris? That’s what I wonder when the after-dinner camera pulls wide. It’s traditional to state that SETI began in 1960, with Frank Drake’s clever experiment in West Virginia. Consequently, we see ourselves as the first generation that’s tried to locate extraterrestrials, and figure that he who dares, wins. But of course we’re not the first. Karl Friedrich Gauss, whose name is familiar to anyone who has progressed beyond high school algebra, had plans to signal Moon dwellers 150 years ago. His schemes to gain the aliens’ attention with flashing mirrors or geometric patterns in the forest seem quaint to us now, but Gauss was not dumb (heck, his brain is in a jar at the University of Gottingen!)

So could it be that, 150 years from now, researchers will look upon our efforts as similarly naïve? Every week I get e-mail from folks who ask me if we’re not being narrow-minded when we assume that sophisticated beings would communicate with radio waves or pulses of light. Of course, these well-meaning people don’t offer any interesting alternatives (they do, however, offer plenty of uninteresting ones!) But, sure; maybe we’re barking up the wrong tree. It would be silly and short-sighted to arbitrarily rule that out.


VLA
The Very Large Array (VLA) radio telescope is used by SETI to listen for artificially produced radio signals from outside our solar system.
Credit:NRAO

But there’s a big difference here. The known universe was claustrophobically small in Gauss’ time. He was trying to signal intelligence on the Moon, or at most somewhere in the solar system. In the last century, a galaxy-filled universe has opened up. We know that planets are ubiquitous, and liquid water might be plentiful. We also know that technology that’s no more advanced than our own could send messages from star to star. Radio waves are fast and energetically cheap. And, although our knowledge of physics is surely incomplete, it could be true (as we think it is) that there’s nothing more efficient for communication than electromagnetic radiation. Unlike Gauss, we have the astronomy, and we have the technology. Our approach may not be the only approach, but it is manifestly feasible – it could work. Of that we’re confident.

The truth of this hits me while observing. Every few minutes, the Project Phoenix screens display a thin smear of bright pixels: yet another narrow-band signal. Each is sent through a cascade of progressively finer filters, to determine if it’s interference or interstellar. So far all have been the former. But looking at these narrow white lines is profoundly reassuring. Our experiment passes the smell test. This is what it could look like, and this is what it would look like. Somewhere out there, if there are worlds easing radio waves into space, their activity would show up exactly so.

It’s nice to think that our generation is special. But there’s also a reason to believe it. Staring for hours at the screens, I can picture – easily picture – a discovery. And then I feel less like an ant. They have no future that’s different from their past. But we do.

The guts of any SETI experiment lie coiled within its digital signal processors. Deep inside these unimposing aluminum boxes, herds of electrons shuttle back and forth at the command of circuitry and software, sorting the incoming cosmic static by frequency, and hunting for the faint, slowly varying tone of distant transmitters.

For more than a decade, Project Phoenix has used digital signal processors originally built for NASA’s SETI search – the one that was halted in 1993. Sure, we’ve improved these devices a great deal, but in the digital world, a hardware design that’s a dozen years old is museum fodder.

The world has turned. The old processor, known to its pals as the Targeted Search System (TSS), is still around, hunkered down in a tractor-trailer container parked outside the observing room. There was so much electronics in this baby that the trailer required 38 kilowatts of full-time air conditioning just to keep the chips cool and calculating. But we use something different now – a new, modular system that is rather straightforwardly called the New Search System (NSS).

The NSS takes up a small fraction of the space of the old signal processor, which means it fits nicely in the Observatory’s computer room, saving the cost of those 38 kilowatts. And yes, it does what the old system did, but the NSS has a radically different architecture’, as the computer jocks would say. You can grasp the architecture by considering a simple analog — Swedish automobile manufacture. Instead of using a single assembly line — which is vulnerable to complete failure at any point – small teams of stalwart Swedes build complete cars from start to finish.

Star field
In a universe brimming with stars, it is difficult to imagine that life exists nowhere else. The infinite multiplied by ‘near-zero’ is still finite.
Credit:NASA/STScI/ESA

The teams of the NSS are called PDMs, or Programmable Detection Modules (the careful reader will note the copious appearance of acronyms in this article. Such is the consequence of engineers’ natural desire for economy of communication,’ or EOC.) Each PDM handles about 2 MHz of the microwave band, splitting incoming cosmic static into several million channels, and searching for signals that appear in those channels.

So what’s the big deal?

Well, the NSS is more than just a replacement for the old system (which, in addition to constant cooling, also required a lot of maintenance.) It’s considerably more reliable… and reliability is important when you’re on the telescope, and every minute is precious. When a PDM fails, scrutiny of the heavens proceeds with the other PDMs. The chance of catastrophic failure that would stop observing is reduced.

As an astronomer who actually sits in front of the glowing ensemble of screens that control the telescope, I experience first-hand the advantages of the NSS. This is far more than a hardware upgrade: the software has also been rewritten. I can now quickly look at incoming signals that are being checked out. Do they look like satellites, or radar, or…? What’s their strength? Their drift rate? Autopilot is nice, but to really get the feel of the craft, you have to poke and pull at the controls.

"This is the most complex project I’ve ever worked on," says Tom Kilsdonk, a tall, soft-spoken software developer who’s been crafting code for the NSS for five years. "I’ve got to say that it’s really exciting to see a plan come together."

Mike Davis, Director of SETI Projects for the SETI Institute, and a former Director of the Arecibo Observatory, is less restrained. "This is impressive as hell," he says. "It shows the real benefits of an object-oriented programming approach."

Not having visited hell yet, I cannot fully gauge Davis’ comparison. But seeing signals pour down the flat panel monitors of the NSS I feel as if I’m "taking the con" on a high-tech ship of discovery.