T he name says it all -- it's a very large array of radio antennae resting 2,124 meters above sea level in the desert of New Mexico. It has been the used in countless television shows, commercials, and science fiction films. A modern marvel utilizing the best physics and engineering of the time to create something that functions larger than it actually is. Strictly speaking, the VLA isn't an antenna, it's an interferometer. That means it uses physics to combine the signals of all 27 dishes into a single signal that looks as if it were received by a dish as large as the distance between all 27 dishes. The overall size of the array can be changed at will because the dishes are arranged on tracks, similar to railroad cars, going in three different directions in roughly a "Y" shape. At its smallest, the array is one kilometer in diameter, but can be expanded to a maximum of 36 kilometers. Each of the antennae are 25 meters in diameter and weigh 230 tons. The VLA is operated by Associated Universities, Incorporated for the National Science Foundation as the National Radio Astronomy Observatory. It's mostly used for radio astronomy on the P, L, C, X, U, K, and Q bands (300-50,000 MHz). But it is occasionally used for tracking satellites and studying the weather. At its most sensitive, it can see a golf ball 100 miles away, but that's not a very good way to get them to notice you. A better way is to knock on their door. Directions are on their web site. The public is welcome.
