If you drive west from Socorro, New Mexico on US 60 about fifty miles, you will find yourself on the Plains Of San Augustin. The plains are about sixty miles long and ten to fifteen miles in width and were formed by Lake San Agustin during the last ice age. They lie between the San Mateo Mountains to the east and the Tularosa Mountains to the west. At first not much catches your eye, just flat grassland. But as you drive farther along, you begin seeing things that really don’t belong in the middle of a dry Pleistocene lake bed.
Scattered across the flat terrain are groupings of large dish antennae, the scene looks like something out of a science-fiction movie. In fact it was in a science-fiction movie. Much of the movie “Contact”, which was based on Carl Sagan’s book by the same name, was filmed at the Karl G. Jansky Very Large Array. And while, in the movie, the main focus of the array was to search for extraterrestrial intelligence, that is not really what scientists at the VLA are engaged in. Instead, they use the antennae to investigate astronomical features of galaxies and stars. The array was instrumental in communicating with Voyager 2 as it flew by the planet Neptune, and much of what we know about black holes, quasars, pulsars, supernovas… is because of observations made at the VLA and other installations like it around the world.
The VLA consists of twenty-eight antennae which are each twenty-five meters in diameter; twenty seven of them are online and working while one goes to the maintenance shed for…well, maintenance. The rest are arrayed along three tracks that are configured in a Y shape with each leg of the Y being thirteen miles long. When the antennae are set in their widest array, they, collectively, constitute a dish which is twenty-two miles in diameter. The individual antennae can be rearranged to suit the needs of the scientists using them. It depends on where, in the universe, they want to look.
To move the massive dishes (each one weighs 203 metric tons), technicians use special trains with pivoting wheels. The trains move along a double rail that follows each leg of the Y to pre-set positions where the train is raised, the wheels pivoted, and the train lowered onto the side tracks, then the dish is placed onto piers and bolted down. The last step is to re-attach all the servo and data cables to make the dish operational. As one can imagine, setting up a new configuration is a time consuming task requiring several days to complete.
Once all the dishes are in their new locations, operators at the Array Operations Center located on the campus of the New Mexico Institute of Mining and Technology in Socorro set the dishes to the correct azimuth and altitude so the scientists can make the observations they need.
The sight of these immense dishes spread across the plain, all looking in the same direction leaves me spellbound every time I see it. I am reminded of the vastness of the universe and of our place in it. The VLA site is a little off the beaten path, but it’s well worth the trip for anyone who looks up at the stars and wonders.