Last Stop, the VLA

Okay, there was one more stop on my New Mexico trip last weekend. After the Trinity site, I went to the Very Large Array (VLA). They have special tours of the VLA twice a year (the same day as the Trinity site is open) although you can visit the VLA any day you wish and do a self guided walking tour.

The VLA is a collection of 27 radio telescopes that combine their signals to make one big radio telescope. They were made famous in the movie Contact (although they do not do SETI work). Each dish is 25 meters (82 feet) in diameter. The radio telescopes are on tracks so they can moved into different configurations. When spread out, they get a very high resolution image of a small part of the sky. When close together, they get a low resolution image of a large chunk of sky. Just think of moving them around as a big zoom lens.

For this visit, they were in what is called the D configuration. The configuration is possibly the most photogenic as they are all very close together. They are set up in the shape of a "Y" and in the A configuration, they use the entire 13 mile length of each track so you cannot see all the antennas at once. Here is a shot of them from Saturday.

Here is a little closer view

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The to move these telescopes and here is one of the vehicles they use to move them.

The dish is off to the right of this image. Note how the track the dish is on are perpendicular to the tracks used to move the dish. That is one tight turning radius! So here's how it works. The dish is put on this cart. The cart rolls to the intersection of the tracks. One corner of the cart is lifted up and the wheels rotate 90 degrees until they are aligned with the other track. They repeat this for the other three sets of wheels and off they do. Might seem convoluted by they saved millions in construction costs by not having to build long sweeping turns of track!

So if you decide to visit the Trinity site, consider the VLA in the afternoon.

Reprinted with permission from the Half-Astrophysicist Blog.