By Jim and Carole Rike
FMCA members (F361571)
After wintering in Mesa, Ariz., as Ohio snowbirds, we decided to take some back roads toward home and to take our time. We drove our 2008 42-foot Allegro Bus to Snowflake, Ariz., and then on to Petrified Forest National Park and the Painted Desert area.
We continued east to the National Radio Astronomy Observatory’s Very Large Array (VLA). It is located on the Plains of Agustin between Datil and Magdalena, N.M., 50 miles west of Socorro. We spent a delightful afternoon at the VLA, situated at 7,000 feet above sea level.
The visitor’s center is open daily from 8:30 a.m. until sunset nearly every day of the year.
The VLA is a system of 27 dish-shaped antennas that work together to form a single large radio telescope. Similar to a camera that intercepts light waves and forms an image on file, each antenna collects incoming radio signals and sends them to a computer where they are combined into a single image.
This is the most powerful and flexible radio telescope in the world today. Since 1980 it has been used in more than 10,000 astronomical observing projects.
Sizing it up
The VLA spans the size of a large city such as Washington D.C. Its legs would extend beyond the beltway around the entire city. Its 27 antennas are placed on three 13-mile-long arms that form the letter Y. The array acts as a single large circular antenna by tracking the radio source over several hours.
If a single antenna were to make pictures as detailed as those of the VLA, the antenna would have to more than 20-miles in diameter.
Each antenna is 94 feet tall, weighs 235 tons -- that is 470,000 pounds. Each dish is 82 feet in diameter. The dishes can be raised or lowered toward the horizon and can be turned to follow the stars across the sky as the earth rotates.
As with so many things today, the heart of the VLA is the electronics. The facility is updating its technologies that date to the 1970s to those that are current state-of-the-art. A new fiber optics backbone will feed into high-speed processors and massive data storage systems.
In the first 30-years of operations, the VLA created a total of about 2 terabytes of data. This data was transmitted from each antenna to the main computer using waveguide transmission technology, which was state-of-the-art in 1965.
The new upgrade will allow data to come from each antenna over 12 channels with each channel sending 1.2 gigabits per second over a fiber optic cable. This will create a data volume of 2 terabytes in about 100 seconds.
The signal received at the base of the antennas can be so weak that any heat in the electronics will mask the data with electronic noise. To prevent this, they cool each collector to 14 degrees Kelvin. That is just 14 degrees above absolute zero. When you are near the antennas, they seem to be singing as you hear the hum of the cooling compressors.
To serve the purpose of the various research experiments that are done here, the antennas are set to four different configurations: A, B, C and D. Configuration A is the largest and has the greatest magnification. D is the tightest. Each configuration is left in place for several months before the antennas move to new locations.
High Plains Lifter
To move these large antennas, they use a unique type of rail road engine called the High Plains Lifter. It moves beneath the antenna, lifts it up and then moves to a new location and lowers it onto its new home.
The lifter provides the antenna with electricity so it can keep the receivers at the required 14 degrees Kelvin while the antenna moves to its new location. Within a few hours, the repositioned antenna can be made operational.
The High Plains Lifter tracks run alongside the actual antenna pad. Because of the size and weight, two railroad lines are used simultaneously by the lifter.
The lifter must be capable of turning its wheels 90 degrees to move from one of the three main rail lines into the antenna pad.
In the last 30 years, the VLA has made major contributions to radio astronomy. It is currently being used to study a massive hole in the universe, an area of space with literally nothing in it. It is estimated to be 1 billion light years across and a mere four billion light years from earth.
The VLA grounds are easily accessible and not an issue for big motorhomes. Guided tours are available a few times a year, but the walking and self-guided tours are easy to follow and wheelchair accessible. The gift shop has a small supply of posters, T-shirts and coffee mugs. Don’t go home without one of the “What’s my problem” T-shirts. They are too funny.
If you are passing through this area, the National Radio Astronomy Observatory’s Very Large Array is definitely worth a visit.
More information: www.vla.nrao.edu.