Karl G. Jansky Very Large Array — radio telescope
The Modern Polymath · CC BY-SA 4.0

Karl G. Jansky Very Large Array

  • Elevation2,124 m
  • 2 min read
  • 34.079° N 107.618° W

Interesting facts

  • Each dish weighs about 209 tonnes, yet the whole array is regularly reshuffled by a lifting locomotive, nicknamed Hein's Trein, that carries antennas along the rail arms.
  • At track junctions the antenna transporter does not need switches: it raises itself on hydraulic jacks and turns its wheels ninety degrees to change direction.
  • In 1989 the array was used to receive radio signals from Voyager 2 as the spacecraft flew past Neptune, the probe's last planetary encounter.
  • There are actually 28 antennas on site: one is always rotated out for maintenance while the other 27 observe.
  • The antennas are moved every three to four months, so the array works through its full cycle of configurations roughly every 16 months.
  • Combined in pairs, the 27 dishes form up to 351 independent baselines, each pair adding one more sample to the synthesised radio image.
  • The receivers cover frequencies from 74 MHz to 50 GHz, wavelengths ranging from about four metres down to seven millimetres.
  • Congress approved the project in August 1972, and the first antenna was set on its foundation in September 1975; the original array cost about 78.5 million dollars.
  • The VLA Sky Survey, begun in September 2017, covers about 80% of the sky and is expected to reveal some 10 million previously unknown radio sources.
  • A planned successor, the next-generation VLA, would use more than 260 smaller antennas, 18 metres across, and be about ten times more sensitive.

Why it is worth it

Twenty-seven white dish antennas, each 25 metres across, stand in a vast Y shape on the Plains of San Agustin, a high, flat basin in western New Mexico. Together they form the Karl G. Jansky Very Large Array (VLA), one of the most productive radio observatories ever built. Every dish rides on rail tracks, and the array is periodically rearranged: in its most compact configuration the antennas cluster within about a kilometre, while in the widest the arms stretch some 21 km each, giving images as sharp as those of a single dish tens of kilometres wide.

The VLA is operated by the US National Radio Astronomy Observatory. Construction began in the 1970s, and the completed array was formally dedicated in 1980. A major electronics overhaul in the 2000s replaced receivers, fibre-optic links and the correlator; at its completion, on 31 March 2012, the telescope was rededicated and named after Karl Jansky, the Bell Labs engineer who first detected radio waves from the Milky Way in 1932.

Its observations have ranged from ice at the poles of Mercury to the jets of distant quasars, from the radio afterglows of gamma-ray bursts to the magnetic structure of the Galactic centre. Since 2017 it has also carried out the VLA Sky Survey, repeatedly mapping the whole sky visible from New Mexico. Beyond science, the array became a film location, most famously in "Contact" (1997), which helped make its row of dishes a symbol of the search for signals from space.

Getting there

The array lies about 115 km from Los Lunas and roughly 50 miles (80 km) west of Socorro along US Highway 60, past the village of Magdalena. The nearest major airport is Albuquerque International Sunport (ABQ), about 141 km away as the crow flies — around a two-hour drive. to 4 p.m. There is no food on site and mobile coverage is limited; drones are restricted and visitors are asked to follow the observatory's radio-interference rules for electronic devices.

On these lists

The Most Beautiful Places in New Mexico 11The Most Beautiful Places in the United States 228The Most Remarkable Radio Telescopes 6The Greatest Modern Engineering Wonders in the United States 7The Greatest Engineering Wonders in the United States 26The Greatest Modern Engineering Wonders 26The Greatest Engineering Wonders 271

From the encyclopaedia

The Karl G. Jansky Very Large Array (VLA) is a centimeter-wavelength radio astronomy observatory in the southwestern United States built in the 1970s. It lies in central New Mexico on the Plains of San Agustin, between the towns of Magdalena and Datil, approximately 50 miles (80 km) west of Socorro. The VLA comprises 28 25-meter (82 ft) radio telescopes deployed in a Y-shaped array and all the equipment, instrumentation, and computing power to function as an interferometer. Each of the massive telescopes is mounted on double parallel railroad tracks, so the radius and density of the array can be transformed to adjust the balance between its angular resolution and its surface brightness sensitivity. Astronomers using the VLA have made key observations of black holes and protoplanetary disks around young stars, discovered magnetic filaments and traced complex gas motions at the Milky Way's center, probed the Universe's cosmological parameters, and provided new knowledge about the physical mechanisms that produce radio emission.

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