Very Large Array

Twenty-seven linked radio telescopes

In the plains of Saint Agustin, west of Socorro, is the Very Large Array (VLA) radio telescope, part of the National Radio Astronomy Observatory, one of the most powerful radio telescopes in the world. The VLA consists of 27 82-foot radio dishes that can be moved on tracks to cover an area as large as 20 by 20 miles. The antennas are linked together to form a single image of the radio source being studied. The facility was constructed from 1974 to 1982 by the National Science Foundation. As part of the National Radio Astronomy Observatory (NRAO), information from the VLA is combined with that from other NRAO facilities at Green Bank, West Virginia; Tucson, Arizona; and the main office at Charlottesville Virginia. For a typical experiment the dishes are configured to track a distant astronomical entity, one which emits radio signals, for a designated amount of time, from several hours to several days. These signals are picked up by the collector dishes, amplified, and transmitted to the control building through underground wave guides. The amplifiers in each dish are cooled to -427 degrees F, just slightly warmer than absolute zero, to reduce the amount of noise they produce. The wave guides are precision-made pipes 60 millimeters wide which steer the cosmic radio waves to the computer processors with minimal loss or distortion. The signals are then converted into data and are stored in computers. The experimenters, who have usually waited for years for this brief window of data-collection, take the computerized data, stored on magnetic tapes, back to their institution to be analyzed and interpreted for months and even years into the future.