The Very Large Array

Beside the Gila Cliff Dwellings and the White Sands National Monument one of the other Top 5 places we wanted to visit while exploring New Mexico was the VLA or Very Large Array. Many many years ago I sat and intently watched each and every episode of Carl Sagan’s original 13-part series Cosmos: A Personal Voyage and remember being intrigued by the VLA then. Seventeen years later I watched the movie Contact and was reminded of Cosmos and the VLA. If that wasn’t enough another seventeen years after Contact a sequel to Sagan’s original was aired, Cosmos: A Spacetime Odyssey and I was again reminded of my childhood interest and decided that if the opportunity presented itself I would make every effort to visit the VLA in person. When this trip came to fruition the geek in me was very very excited. Willow…could not have cared less, although she got more than a few pets and head scratches from some of the other visitors who were there. So for me, Geek Fest. For Willow, boring but some bonus activity.

Willow sitting in front of the VLA entrance sign
At The Entrance Road Sign, Dog Boredom Setting In
Our Tacoma With The Tightly-Grouped Antennas Behind Us
Our Tacoma With The Tightly Grouped Antenna Array Behind Us

Situated on the Plains of San Agustin in central New Mexico, this site met all the requirements a radio telescope would want: high, flat, dry, and surrounded by mountains which block man-made radio noise from nearby cities. During the last Ice Age, about 11,000 years ago, this 45-mile long, 12-mile wide area was filled by an enormous lake. Now dry, it has been witness to thousands of years of human occupation, more than a hundred years of settler activity and nearly 50 years of bleeding-edge astrophysics research.

Run by the National Radio Astronomy Observatory (NRAO) the installation was officially renamed the Karl G. Jansky Very Large Array in 2012 after a decades-long technical upgrade that replaced the 1970’s era technology with new, state-of-the-art electronics. This upgrade was essentially an across the board tenfold increase of the VLA’s capabilities.

Approved by congress in 1972 construction began in 1973 and it went online in 1980. This group of 28 dish-shaped antennas (27 active and 1 spare) is arranged along the arms of an upside-down Y (called the Wye) and can be moved along dual sets of standard gauge railroad tracks into four distinct placements and those moves happen about every four months, weather (especially wind) permitting. There are about 40 miles of track laid on 60,000 wooden ties in the Wye configuration. Each of the Arms (the Southwest, Southeast and North arms) is 13 miles (21 km) long and has 24 stations where each of the nine antennas (per arm) can be mounted depending on the configuration. When we visited it was in the D-configuration when the dishes are sitting in the first nine stations from the center of the array on each arm – as close together as they ever are and when each grouping of antennas is about 2/3 of a mile long. In the A configuration the nine dishes are spread so that the dishes farthest out on each arm are about 22 miles apart! When used together the array of individual antennas essentially becomes one large configurable radio telescope for use in radio astronomy.

Willow sitting with the VLA in D configuration in the background
In The Compact D Configuration

As we understand it, moving the antennas along the rails changes the array’s resolution. In the most compact D configuration the array “sees” in its widest field of view and in the A configuration it is like zooming in with a telephoto lens. After watching the 20 minute movie in the Visitor Center we paid the entrance fee ($6 normally, $5 with our AAA membership) and were handed the map directing us along the stops of the self-guided walking tour.

We first took a quick walk around the Visitor Center itself to take a look at the many small but interesting, informative and historical displays.

Cut-Away Of A Feedhorn And Receiver That Was Replaced In The Recent Upgrade
Cut-Away Of A Beautifully Machined Aluminum Feedhorn And Its Receiver

Several signs mentioned in no uncertain terms to turn off your phone or, at the very least, put it in “Airplane Mode” as the emissions from something even as small as that are Trillions (with a capital T) of times stronger than the signals from outer space they are capturing here. While I know the San Agustin valley the VLA is situated in is not officially a United States National Radio Quiet Zone one could be forgiven for thinking that it might be. I have mentioned before that in our experience AT&T seems to generally suck when it comes to coverage in areas that are not large metropolitan zones. With that constant disappointment in mind though there still seemed to be an even larger and more thoroughly complete dead zone here than their normal suck factor. There was a complete and utter lack of cell phone reception from several miles to the west of Pie Town down into Datil, across the valley where the VLA resides, through the gap in the mountains where the town of Magdalena sits and all the way until we entered Socorro. That’s like an 85 mile stretch of suckiness (a.k.a. non-existent) cell reception which almost begs the question of if there is a non-official, gentleman’s agreement between the NRAO and wireless companies to reduce or eliminate radio interference in the area. Either that or it’s just AT&T being as sucky as usual. We’re leaning towards the latter explanation.

The small group that was in the Visitor Center theater with us also headed out on the walking tour at the same time. Choosing to not be crowded with that group we gave in to our anarchistic tendencies, ignored the suggested ordering of the 16 tour stations and drove over to #16, the Antenna Assembly Building (AAB), which is commonly called “The Barn” by the workers on site.

Antenna Assembly Building
The Barn Was Empty On Our Visit

This is the building where all 28 antennas were originally constructed between 1973 and 1980. The parabolic dish of each antenna has a diameter of 82 feet (25 meters) and the whole assembly weighs 230 tons. Every two months one of the antennas is brought into the AAB for routine, scheduled maintenance. There workers give it a thorough inspection and fix or replace any parts that need servicing. Then it is back out to the Master Pad and after it passes its post-service testing it gets rotated back within the active array and another one is pulled out of service for its regularly scheduled tune-up. When the antennas need to be moved, either during a configuration change or for maintenance they are lifted up by one of two massive, custom-made transporters which slowly and carefully move them along the tracks to their next destination. Depending on the length of the move it can take anywhere from a couple of hours to move one antenna between nearby pads and two whole weeks to move all 27 antennas during a change of the whole configuration. During each and every move the transporter has to power the cryogenic cooling units running inside each antenna which keep the delicate electronics down around 15 degrees Kelvin (-432.67 F). That’s 15 degrees above absolute zero! These transporters deserve a post of their own but I will fight my urge to geek out on them and bore you to death and instead just list a few links if you would like to see or learn more about these interesting machines that play a pivotal (pun intended) role in how the VLA works.

From the AAB we walked the 100 feet over to the Master Pad itself where each newly serviced antenna is placed while is goes through its checkout before being put back into the main configuration.

Newly Finished With Its Maintenance Visit An Antenna Sits At The Master Pad Undergoing Testing
Newly Out From Its AAB Visit An Antenna Sits At The Master Pad Undergoing Testing

This was the first pad ever completed and the first to have an antenna on it way back in 1975. This is also the place where Willow first caught a whiff of some dog who had been here previously and left its mark. Yes, dogs are more than welcome as long as they are “good” dogs and you clean up after them. All hints of boredom now gone she perked up and immediately went into Chemical Warfare mode and gleefully overmarked each and every aromatic spot she came across for the rest of the walk.

Willow Sitting Next To The "Spare"
Sitting Next To The “Spare” Of The Moment

We are guessing but assume that the “No Parking Within 50 Feet” restriction is so that the electromagnetic interference from a (non-diesel) motor vehicle’s ignition spark does not meddle with the sensitive electronics inside the antenna itself. That is another reason for the cryogenic cooling of the electronics inside the antenna – (IIRC) the colder the equipment is, the more efficient it is and the less electromagnetic energy it emits itself which could interfere with the radio frequency energy being collected by the antenna.

There are now 72 pads spaced out along the three arms and two others for maintenance and testing (which I believe are the Master Pad and the one in the AAB). Each pad has three piers that the antenna sits on and is bolted to. These piers also have ports to supply power and data to each antenna as well as return the collected data back to the Control Room for further in-depth analysis.

Looking Down A Section Of Track To An Empty Pad Where The Northern Arm Crosses Highway 60
Looking Down A Section Of Track To An Empty Pad Where The Northern Arm Crosses Hwy 60

It is a bit disconcerting to sit and take the above picture as you have to disregard your preservation instinct to Not Sit On Railroad Tracks. The transporters move at the glacial pace of 2 miles per hour so I’m pretty sure we would see them long before we would ever be in danger.

After our stop at the AAB we drove back to the Visitor Center and did the walk around the other stops on the self-guided tour. At each stop there was a plaque asking a question and then giving you the answer and sometimes a visual aid as well. Kind of like a real life FAQ section.

One stop on the tour had an extra antenna from the nearby and relatively new Long Wavelength Array (LWA) with a plaque explaining its function.

LWA Antenna
LWA Antenna
LWA Antenna Information Sign
LWA Antenna Information Sign

As we continued on the tour we eventually came to the two-story Control Building where the business of operating the array takes place. We walked up to the second floor where there is an outside walkway looking out over the array.

View of the Array from the 2nd stoy of the Control Building
From The Second Story With The Building’s Shadow Creeping Towards The Array

180 degrees from the view above is the wall of windows that the scientists and technicians who work in the building use to look out at the array. The glass was heavily tinted but we could still see computer monitors, desks and movement inside. If we could see inside they could see outside so I held off picking my nose until we got around the corner and began walking down the stairs. Kidding…or am I?

Out in the courtyard on the side of the Control Room not facing the Array there sits a piece of sculpture that, to me, invokes images and thoughts of satellites and science fiction. Called SHIVA: SHIWANA it was created by artist Jon Barlow Hudson in 1980 to commemorate the dedication of the VLA.

Funded by the New Mexico Arts Council the welded and brushed stainless steel piece represents the Y shape of the VLA’s tracks and the 3-dimensional nature of the objects the giant telescope studies. We found out the sculpture’s information while doing the extra research for this post but could reasonably assume it was made in 1980 by the date welded directly into the base.

1980 date welded into the base of a sculpture
We’re observant that way.

Our time at the VLA coming to a close we made our way back towards the Visitor Center and our Tacoma parked in front. This is one of the most technologically advanced pieces of scientific equipment in the world. The level of access and information available to the public is refreshingly open and accessible for a government installation. Much of the grounds and most of the self-guided tour are accessible to the mobility impaired. If you or any member of your family or friends have even the slightest interest in the subject of radio astronomy or outer space this is a must visit and see destination which I (and now Willow) highly recommend.

Driving away from the VLA compound we decided to spent the night at the Datil Well Campground. It’s about 20 miles and 25 minutes back up into Datil but nice, clean, cheap ($5) and almost empty. In the town itself there is a small combination grocery store/restaurant/gas station with reasonable prices, a nice selection and friendly service. When we pulled into the campground itself we had the place to ourselves for a couple of hours. Just after dark one other vehicle arrived and they smartly and considerately made use of a spot on the opposite side of the campground from where we were. Like everywhere else in the area AT&T decided to not work but for a quick overnight stay it was a nice place and we’d have no problem staying there again.

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