Thursday, September 22

Expanded VLA


Almost any science fiction fan can identify an image of the Very Large Array (VLA) radio telescope. This impressive collection of 27 mobile antennas was the opening backdrop for "Contact", a screen adaptation of Carl Sagan's popular novel, starring Jodi Foster. In the movie, Jodie's character detects the first signals from an alien species while relaxing in the shadow of the array.


The VLA sits on the Plains of San Agustin, a desolate plateau in western New Mexico, more than 50 miles from the nearest city. They make for a spectacular scene as you crest hills circling the plateau. Each of the telescope's white dish antenna measure 25 metres is diameter and weighs a hefty 230 tons. They ride on railway tracks that enable them to fan out along a Y-shape configuration up to 37kms apart. Two of the three rail arms even extend across local highways.

The complex was originally authorized by the US congress in 1972. It officially opened in 1980 after more than 16 years of steady construction. The US National Radio Astronomy Observatory (NRAO), a joint venture between the nation's universities and the National Science Foundation, maintains the facility and controls its use.

In 2001 the NRAO began work on the US$98 million Expanded VLA (or EVLA) project. The project, due for completion next year, is an extensive technology upgrade designed to make the telescope ten times more sensitive to faint radio frequencies. Its 1970's-vintage electronics, analogue data tranmission systems and computing technoology are being replaced by modern optical fibre technology and a new, powerful supercomputing able to process in an hour the same volume of data collected by the VLA during its first thirty years of service.


Garry and I visited the EVLA today enroute to Arizona. We couldn't have picked a better day to visit. The array is currently being transitioned from its most compact formation. This meant we could see all 27 antennas in close proximity and watch its special red transporter unit carefully relocate the gleaming white dishes. Visitors are enable to take a self-guided walk around the facility including a close-up look at one of the active dishes. We were also lucky enough to see a dish ungoing repair in the facilities giant covered workshed.

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