Blown away by the Very Large Array

On the Plains of San Agustin, 27 huge dish antennas make up the world's largest radio telescope. Photos: Astronomy central

DATIL, N.M.--I'm standing in the middle of "the center of the known universe," as this room is sometimes called. And in a way, it feels like that's actually where I am.

That's because I'm in the control center of the Very Large Array, a collection of 27 dish antennas, each of which weighs 230 tons and has a diameter of 25 meters. Together, the antennas form the world's largest radio telescope.

The VLA, as it's known, is a true sight to behold. It is located at 6,970 feet in the Plains of San Agustin, about 50 miles west of Socorro, N.M., and I've come here as part of Road Trip 2007, my journey around the Southwest in search of some of the most interesting science- and technology-related destinations. This definitely counts.

This is awesome country, with gorgeous brown and tan mountains, a huge sky and, it turns out, some of the most advanced and prodigious scientific equipment the world has ever known.

You try looking at more than two dozen giant dish antenna spread over a giant plain on a beautiful day and not be impressed. Almost impossible.

Together, the 27 antennas combine to create the resolution of a single antenna 22 miles across, with the sensitivity of a dish 130 meters in diameter, according to the VLA's Web site. What that means is that "you can make images of almost anything you can look at in the universe," Dave Finley, the public information officer for the National Radio Astronomy Observatory (NRAO), which operates the VLA, told me.

The VLA is a radio telescope, a message that Finley and the NRAO are eager to have people understand. But it doesn't collect sound. It collects radio waves, which, Finley tells me, are exactly the same as light waves. Only different.

Finley explains that optical telescopes like Hubble and Palomar are designed to collect light waves, while the VLA collects radio waves. The end result is the same: To understand what's going on in the universe. And it seems that the VLA is doing a good job of that.

"The VLA is the most scientifically productive ground-based telescope in the history of astronomy," Finley said. "There are between 180 and 200 scientific papers a year that announce discoveries" based on research done at VLA.

The VLA is a project of the National Science Foundation, and as such, is available to any scientist who wants to use it, and who submits a successful proposal.

Finley explained that the NRAO receives about two hours of proposals for every hour of available time on the VLA, so it's a competitive process. But those who are accepted get access to incredible machinery.

The VLA was designed and built in the 1960s and '70s, and it was dedicated in 1980. Today, it is undergoing a multiyear process to upgrade all of the antennas from analog systems to all digital. This project, known as the Expanded Very Large Array, is expected to be completed by 2011 or 2012 at a cost of about $75 million.

Road Trip 2007 promo

Finley explained that the upgraded VLA will be 10 times more capable as a scientific instrument than it was originally.

Today, the project is well under way, with 11 of the antennas having already been upgraded, and one literally being worked on while I'm here.

It's quite a sight, actually: a giant building, known as the "barn," with one of these mammoth antennas inside it. It's kind of the astronomy version of an auto mechanic, with the antenna seemingly up on blocks and technicians banging away at it, to make the necessary changes.

One major piece of the upgrade involves switching out the old analog microwave waveguide systems--essentially pipes that signal waves traveled through--with modern fiber optics.

Another major piece is installing a new "correlator," the complex system that takes the signals from all 27 antennas and combines them into one cohesive signal.

The current correlator is an all-analog system that's going to be replaced by a new one to be donated by Canadian scientists as their contribution to the Expanded Very Large Array.

The net effect of the upgrade, Finley says, is to get the equivalent of 10 VLAs for the cost of about one-third of the original (taking the original costs and factoring in inflation).

The idea, he explained, is to keep the VLA at the forefront of astronomy for the foreseeable future.

"We've already marked our 25th anniversary," Finley said. "I'm pretty sure we'll have people here to mark the 50th."

One major challenge associated with the upgrade is not reducing the amount of research that gets done while the antennas are being worked on. Finley said that for the most part, the VLA has been able to meet that goal, though there have been times when not all 27 antennas are available at the same time. But while that means slightly less data is available, it's not a critical problem, he said.

One question I had was why the VLA is here on the Plains of San Agustin, of all places. Clearly, it's good to have a place large enough to spread out three arms many miles long, but there are plenty of those in the West.

Finley said the Plains of San Agustin--which, he added, are about as big as Connecticut--were the perfect location because of the NRAO's criteria: a large, flat and dry site at high elevation that's away from large population centers so there is no problem with radio interference, but a site that is also close to good highways so it's easy to get equipment and people in.

Thus, here we are.

Today, the VLA is in its "A" configuration, which means all three arms are spread out over the many miles. But the antennas at the VLA can actually be moved into seven different configurations depending on the time of year and the specific scientific need.

The "D" configuration is the one most tourists--including myself--want to see because that's when all the antenna are clustered closely, all within .4 miles to the center. But alas, it wasn't to be. There's actually an online schedule for the different configurations, with "A" running until September 10.

And moving them is quite a production. The VLA has two giant transporters that lift the antennas and move them, on railroad-style tracks, from "pier" to "pier," the anchors where the antennas are locked down.

The whole idea behind the VLA, meanwhile, is to create as many different pairings of antennas--and the signals they can receive--as possible, and then combine them.

With 27 antennas, Finley explained, there are 351 different possible pairings. So the concept is to receive a signal with all these pairings, then turn the antennas a little and start over. That means another 351 sets of signals to add to the mix.

"So when you rotate the antennas, you get 351 new pieces of information," Finley said. "And Earth's rotation gives you 351 (more). You do it enough that if you have good enough software and computing power, you can get a good enough image."

Ultimately, that's what the VLA is about: imaging the universe. Even though it's a radio telescope, it produces images, not sounds. It's a common misconception that Finley said he is constantly trying to overcome.

To me, unfortunately, it's all a little bit of Greek. I can, however, understand the impact of so many of these incredible antennas, and how they can produce the data that is moving the science of astronomy forward.

And as I look out over the many, many miles of the plains, admiring the antennas far off in the distance, as well as the ones up close, I can't help but be captivated by the feeling that I'm at the center of the universe. Even if only for a little while.

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