70 Years of Telescopes Tuned to Cosmic Radio

Written by on 25 October 2009

Radio astronomy began with static. Bell Laboratories wanted to get rid of it and went looking for its causes. With a hand-built radio telescope, Karl Jansky discovered a clear signal of something else amidst the noise from thunderstorms near and far: a steady static that appeared to emanate from the center of the Milky Way. The field of studying radio waves arriving at Earth from outer space was born. Jansky didn’t know what could be causing the radio waves, and Bell Labs pulled him off the project soon after his big discovery. Still, he’s considered the father of radio astronomy. This gallery illustrates the progression of radio telescopes from Jansky’s primitive ’scope to the huge arrays of antennas now installed in the world’s deserts and perhaps, one day, on the moon. Inspired by Jansky’s work, Grote Reber, a young ham-radio operator and engineer, wanted to know more about cosmic radio waves. He applied for a job with Bell Labs, but it was during the Great Depression, and he never landed a gig. So, Reber built his own 30-foot parabolic radio telescope in his backyard in Wheaton, Illinois, pictured above. The parabola is a useful shape for astronomical equipment because it allows scientists to gather up electromagnetic waves and focus them to a single point where they can be amplified and recorded. The chart output of his recording equipment is pictured below. The little spikes are interference from car engine sparks. During the day, the interference was so bad that it made his work impossible, so Reber did most of his work alone at night. John Kraus, a physics and engineering professor at Ohio State University, was the third in the triumvirate of legendary early radio astronomers. He designed the Big Ear radio telescope pictured here, building it with student labor and just $250,000 in 1963 (equivalent to about $1,750,000 in today’s money). The structure, which Kraus designed, was unusual, and it was larger than three football fields. The flat reflector (right) picked up radio waves from space, bouncing them to the parabolic reflector across from it (left). The parabola focused the waves onto the actual recording equipment, located on the plane between the reflectors. It became the first — and longest-listening — telescope to be used continuously in the Search for Extraterrestrial Life program. Kraus also wrote the books, Antennas and Radio Astronomy, which are considered classics in their fields. Like their optical colleagues, radio astronomers knew that bigger telescopes meant better resolution and the ability to go deeper into the universe. They began to scale up the size of their telescopes. This huge 300-foot telescope was installed at the National Radio Astronomy Observatory in Green Bank, West Virginia, in 1962. It operated continuously for 26 years until its stunning collapse from a girding failure in 1988. While individual telescopes were getting bigger, scientists were also mastering the technique of very-long-baseline interferometry for making very-high-resolution radio-wave observations. With the aid of very precise atomic clocks, astronomers could combine the data from arrays of antennas. In effect, groups of telescopes began to function as one observatory. Here, we see the Very Large Array, which is located about 50 miles west of Socorro, New Mexico. Radio astronomy doesn’t naturally produce stunning images of the heavens, but then again, neither does most astrophotography. In this photo, we see a tremendous visualization of the radio waves emitting from a strange elliptical galaxy, NGC 1316. Gas heated to 10 million degrees by the galaxy’s collision with a smaller neighbor emits the radio waves you can see as the false-color “lobes” in the image. It’s been superimposed on an optical survey of the region. As human beings and their machines pushed farther away from Earth, NASA found itself in need of a powerful communications tool for sending and receiving messages to spacecraft. The Deep Space Network of antennas became that interplanetary cell phone. Three nodes located approximately 120 degrees away from each other on the Earth — Spain, California and Australia — allow space engineers to keep contact with spacecraft throughout the Earth’s daily rotation. Here we see one of the antennas at the Goldstone Deep Space Communications Complex near Barstow, California. The Robert C. Byrd Green Bank Telescope is the world’s largest, fully steerable radio telescope. Completed in 2002, its dish has a slightly asymmetrical design, measuring 100 by 110 meters )328 by 361 feet). The dish is composed of 2,004 surface panels controlled by 2,209 individual actuators. The telescope’s 16 million pounds of moving weight can be adjusted with sub-inch accuracy. The Atacama Large Millimeter will become the largest radio telescope in the world when it goes online in 2011. Its 66 antennas will be located in the Chilean Andes at an elevation of more than 16,000 feet. The dry air in this incredibly remote place will allow scientists a nearly transparent window for making observations. Here, we see the first of the antennas being trucked up to remote observatory site. Astronomers have long dreamed of putting their instruments on the moon, particularly the far side, where there’d be little interference or atmosphere to get in the way of their observations. Back when President George W. Bush’s Vision for Space Exploration still seemed kind of viable, space scientists thought their dreams might come true, even awarding grants to explore what radio telescopes on the moon might look like. Now, with NASA’s return to the moon up in the air, it seems unlikely any astronomical instruments will end up on our satellite any time soon.