Science at the Edge of Human Scale: the Very Large Array

While planning our trip, Lizzie and I realized that we would have an awkward amount of extra time between our visits to the Superconducting Super Collider and Los Alamos. Though the drive from east Texas to New Mexico is formidable enough to require a night’s stay along the way, it has such high speed limits and so few turns that the miles tick by more quickly than just about anywhere else in the country. But since the July 4th weekend meant that we had to be at Los Alamos by the 2nd – unless they’re in the middle of a particularly intensive run, physicists get the same holiday weekends as the rest of us – there was only about a half-day to spare.

This wasn’t enough time to accommodate our original idea of camping at White Sands and driving by the Trinity Test Site (which is closed to the public all but two days a year anyway). But it turned out to be just the right amount of time to visit the accurately if unimaginatively named Very Large Array (VLA), located about 50 miles west of Socorro, New Mexico.

The heart of the Very Large Array

A wider view of the heart of the VLA. As the view extends outward, the scale starts to become apparent.

Click through to view an enormous panorama of the VLA. Even though the Array was not at its most outspread position, this enormous image still does not capture the whole thing.

Nestled on a vast, mountain-ringed, 7000-foot plateau in the central New Mexican desert, the VLA is safe from the interfering radio waves of just about anything that doesn’t come from space. Though it is comprised of 27 separate dishes, the observatory operates as a unified whole: by interferometrically combining the data from each dish, the array can simulate the results of a single radio telescope up to 22 miles wide.

One of the 230-ton, 28-meter diameter VLA radio telescopes. Note the railroad cars for scale.

As you can see from the railroad cars in the above picture, the telescopes themselves are absolutely enormous. Even more astoundingly, they move: placed on sets of railroad tracks, the dishes can be carefully shifted en masse to create one of four different total areas that correspond to different angular resolutions, each used to observe differently-sized chunks of the sky. The system works so efficiently that the gargantuan task of moving the dishes can be undertaken frequently, about once every four months. This ease of movement allows the observation of a tremendous range of celestial objects and variables, which, along with the fact that the observatory can operate during the daytime, helps to make the VLA the most-used radio telescope in the world.

Sunrays shine through the clouds onto the VLA, illuminating both the telescopes and the train tracks used to move them around the observatory.

This transportability also makes it easy to maintain the telescopes, as they can be rotated in and out of service as maintenance is required. Thus, although the functional array makes use of 27 dishes, the VLA has a total of 28. One dish is always undergoing routine servicing in the Antenna Assembly Building.

The rotating 28th antenna of the array, undergoing routine maintenance in the Antenna Assembly Building.

At its most outspread, the VLA’s footprint is larger than the Washington, DC metropolitan area (see map below). Because of this tremendous size and the flat terrain, you can see the observatory from miles away. Yet the plains that house it are themselves so vast that the installation is dwarfed by its backdrop. Indeed, it takes so long to walk among the telescopes that the observatory management has posted lightning warnings for visitors who wish to take the self-guided walking tour, and even in the midst of the array the furthest dishes seem ludicrously distant.

The VLA is so large that its arms could engulf the Washington, DC metropolitan area at its widest stance.

The VLA is enormous, but the plateau that houses it is larger still. Even in the midst of the telescopes, the most distant dishes seem tiny against the backdrop of plains and distant hills.

As such, the Array exists the very edge of human scale: too large for people to traverse it on foot, too small to compete with the surrounding landscape. More vividly than any other single site we visited this summer, this paradoxical size illustrates one of the unifying themes of the trip as a whole: Big Science tends to use increasingly enormous and complex machines to access parts of reality that would otherwise be inaccessible. Walter Benjamin touches on this phenomenon during his discussion of filmmaking in The Work of Art in the Age of Mechanical Reproduction:

[I]n the studio the mechanical equipment has penetrated so deeply into reality that its pure aspect freed from the foreign substance of equipment is the result of a special procedure, namely, the shooting by the specially adjusted camera and the mounting of the shot together with other similar ones. The equipment-free aspect of reality here has become the height of artifice; the sight of immediate reality has become an orchid in the land of technology…

The characteristics of the film lie not only in the manner in which man presents himself to mechanical equipment but also in the manner in which, by means of this apparatus, man can represent his environment… This circumstance derives its chief importance from its tendency to promote the mutual penetration of art and science. Actually, of a screened behavior item which is neatly brought out in a certain situation, like a muscle of a body, it is difficult to say which is more fascinating, its artistic value or its value for science.

In just the way in which artists frequently disguise the artifice of their methods of production, scientists work hard to eliminate as completely as possible the influence of their equipment on their results – indeed, the manner in which scientists carefully account for apparatus-induced error is a substantial part of what makes science science. But Benjamin implies something more: there is a real tendency for larger and more complex apparatus to cut more broadly and deeply into reality. So long as care is taken to hide the lights and microphones, camera and crew, the complex artifice of filmmaking can reveal more than unadulterated reality would; so long as care is taken to account for the influence of an inhumanly complex apparatus, Big Science can reveal ever more about the fundamentals of our world.

It is no surprise, in this light, that the machines that allow these groundbreaking studies of nature are often so astoundingly and increasingly large that they rank among the largest construction projects ever undertaken by humanity. (The VLA’s size requirements are at least partially related to the large size of the phenomena it measures; at many of the other laboratories we visited, the enormity of the machines was required to measure the very small.)

But as Fermilab’s Dr. Peoples sadly notes, this also means that particle physics will eventually build a “last machine” on the energy frontier. At some point on the path that physics is on – to be determined more by cost and other practical concerns than by nature – new discoveries in this realm of physics will truly move past the human scale and into the natural scale, beyond our ability to follow. Thus, the Faustian nature of Big Science: enormous rewards for the money, but at what often seems to be an ultimately unsustainable cost and pace.

Though tremendously expensive, the VLA was completed a year ahead of schedule and under budget, and has been used 362 days a year for the last thirty years – a marvelous success by any measure. On the other side of the spectrum, the failure of the Superconducting Super Collider and the difficulties that the Large Hadron Collider ran into during its first start up are signs that particle physics may already be stretching Benjamin’s bigger-is-better mode of exploration to the breaking point. We can only hope that this approach is made obsolete by the time that frontier hardens before us, that the need for larger and more expensive machines is replaced by more powerfully efficient methods. As Lizzie noted in our accelerator development post, development of the International Linear Collider is being channeled through more quickly realizable intermediate experiments like Project X, while research into more efficient accelerator methods continues around the country.

In this respect, the VLA embodies another important principle: rather than building one 22-mile dish that would have cost about as much as it would to colonize Mars, it made use of scientific principles to simulate such a dish with nearly equal scientific results. Although such shortcuts aren’t always possible, the more cleverly that science makes use of its own discoveries, the more feasible it becomes to carry out new work.

-Nick

A row of VLA radio telescopes.

A row of VLA radio telescopes.