The Very Large Array
As the name implies, this incredible astronomical instrument is a very large array of twenty seven enormous radio antennae scattered across the New Mexico desert, scanning the heavens day and night for faint radio signals.
Hidden on a high desert plateau, behind mountains, far from human radio sources that would completely blind their extremely sensitive receivers is a set of 81 ft. diameter identical radio dishes laid out in a Y configuration. These antennae are synched using a technology called interferometry so that they can synthesize the an effective aperture of a telescope more than 25 miles across. The dishes sit on concrete piers, but every three months they are moved to a different configuration to mimic a telescope of a different size. How do you move a 230 ton radio telescope across the desert, let alone twenty seven of them? A custom locamotive platform that rides on parallel sets of railroad tracks slides under each dish, lifts it, and carries (very slowly) to a different set of concrete piers. These tracks (and concrete piers) extend in all three directions of the Y for 13 miles from the center. Depending on the current configuration, the dishes could be miles apart from each other, spread across the desert, or if you’re lucky they could be in D configuration (the most photogenic), packed tightly near the center of the Y. Regardless of what configuration they are in, one antenna will always be at the position closest to the visitors center so you can get a close up view of one of these giants. Stand next to this dish for a few minutes and listen to the enormous electric motors hum, as they guide the telescope across the sky while tracking an object. Every few minutes, each dish in the array will simultaneously slew (telescope lingo for move) to a radio calibrating source. It’s impressive to see how fast and smoothly these behemoths move.
Check what configuration the VLA will be in when you visit. A-configuration is the largest, D is the smallest. https://public.nrao.edu/vla-configurations/
ALIENS
A misconception of the science conducted at the Very Large Array, is that the antennae are listening for communications from extra terrestrials. That is not the case. While SETI (The Search for Extra Terrestrials Intelligence) has used the VLA in the past, that is not a primary objective of the telescope.
WHEN TO VISIT
Any day of the year you can drive down to the VLA and get a look at the array, although probably not very close (unless you’re lucky and the array is in A or B configuration which puts an antennae at the piers alongside US-60). To get a better view of the dishes, and the operations, take a tour! On the first and third Saturdays of every month, VLA staff will take you through the facility giving interesting facts, tales, and unfathomable statistics (and answering questions) about the science conducted here. Tours are $6, take about an hour, and begin at 11:00 AM, 1:00, and 3:00 PM. Two times per year the VLA holds open houses, which are essentially the same as the standard tours, but more of the VLA staff is on site to answer all of your questions and give more focused lectures on different aspects of the VLA. Open house tours are free and run at 11:00 AM, 1:00, 3:00, and 5:00 PM on the first Saturday of October and March. If you’re visiting from out of town, you just might be lucky enough for the open house in October to line up with the Trinity Site tour (also only available twice per year) and the Albuquerque International Balloon Fiesta.
