Restoring Historic Radio Telescopes

Today’s state-of-the art technologies become tomorrow’s obsolete castoffs as scientific frontiers advance. Radio telescopes built in the 1950’s and 1960’s pioneered radio astronomy and tracked spacecraft during the early Space Age. Groups of amateurs restored several historic telescopes to conduct amateur and student radio astronomy research.

Amateurs pioneered radio astronomy. Karl Jansky, a radio engineer, accidentally made the first radio astronomy observations in 1932-1933 while trying to find a radio source that interfered with AT&T’s long-distance radio telephone service. One of those sources lined up with the center of the Milky Way. Grote Reber, another radio engineer, was fascinated by the concept of radio emissions from deep space. Unable to get a research job due to the Depression, Reber used his own money to build the first parabolic dish radio telescope in the backyard of his Chicago-area home. Reber confirmed Jansky’s discovery in 1937. Even though Reber wasn’t a professional astronomer, his work over the next decade laid the foundation for radio astronomy’s development following the Second World War.

A wave of radio telescope and radio antenna construction began shortly after the war and lasted throughout the 1950s and 1960s. Driven by the new technologies of long-distance, especially satellite, communications and the rapidly developing science of radio astronomy, universities and government agencies built ever-larger dishes. The technology of radio telescopes hit their limits with the construction of 100-meter telescopes in Germany and the United States. Even these enormous dishes are too small to answer the questions of modern astronomy. Cutting-edge research now depends on vast regional arrays of smaller telescopes like the Very Large Array and the Square Kilometer Array. Observatory operators must make hard choices. The National Science Foundation, for example, will divest several telescopes including the 100-meter Green Bank Telescope to pay for new observatory projects. 

In some cases, they find other uses for the telescope. The Echo telescope at the Jet Propulsion Laboratory’s Goldstone Observatory, for example, was once part of Nasa’s Deep Space Network. Now high school students use the telescope to study the giant planets and distant pulsars as part of the Goldstone Apple Valley Radio Telescope project. The U.S. Navy built a 20-meter telescope in the 1990s at the National Radio Observatory for geodetic research, but shut it down in 2000. The University of North Carolina now uses the telescope in its Skynet education and research telescope network.

One historically significant telescope that has found new commercial purpose is the Algonquin Radio Observatory. Built in rural Ontario, the 46-meter radio dish became the largest Canadian radio telescope when it opened in 1966. Its design was used to build the Parkes Observatory in Australia which, in turn, inspired the design of Nasa’s Deep Space Network telescopes. Canadian astronomers used the Algonquin telescope in the first demonstration of very long baseline interferometry (DOI: 10.1126/science.156.3782.1592), inadvertently sealing the telescope’s fate as the technique surpasses single-dish telescopes. According to the Virtual Museum of Canada's history of the Algonquin Observatory, the National Research Council closed the observatory in 1987 to focus on research at more advanced observatories. Space systems company Thoth Technology leased the telescope and renewed operations. The Globe & Mail’s report on the return to operation of the Algonquin Observatory highlighted the innovative pulsar research that’s still possible with the old telescope. Thoth markets the telescope’s abilities for space communications and scientific research. Space tourists can experience life at Agonquin by staying at Observatory House. Built as a residence for astronomers in the days before the Internet, it is now a hotel. Guests can take a tour of the telescope, enjoy the park surrounding Lake Traverse, and attend nightly star parties.

European amateurs have restored several historical radio telescopes to support amateur and student research. Radio amateurs in the Netherlands formed a foundation, Camras, to restore the 25-meter telescope at the Dwingeloo Radio Observatory. The largest dish telescope in the world when it was built in 1956, it fell out of use by the end of the century. The amateur and professional volunteers at Camras convinced the telescope's owners at the Netherlands Institute for Radio Astronomy to refurbish the national monument in 2009. Camras now operates the telescope as a public observatory. A year before its official opening in 2014, the Dwingeloo telescope rescued a satellite. The Triton-1 CubeSat reached orbit in late 2013, but its radio system couldn’t receive signals from ground stations. Camras volunteers used the much larger Dwingeloo dish to blast a stronger signal at the satellite than the ground stations could generate. Yelling did the trick. Triton-1 woke up.

German amateurs took on a similar project restoring the Sternwarte Bochum, a 20-meter radio telescope built for a Volkshochschule, an adult continuing education center. After a storm destroyed the inflated radome structure in 1999, the state government restored the physical structure and turned it into an industrial monument. The restoration did not include the updated control systems or instruments needed to operate the telescope. Amsat-DL, the German amateur satellite group, offered to refurbish the radio dish in exchange for using the telescope for its planned deep space missions. The amateur satellite-makers used the telescope to bounce radar signals off Venus - a first for Europe - and detect signals from Mars Express and the Mars Science Laboratory while the spacecraft were en route to Mars. That deep space capability lets the German amateurs support the space agencies. They are part of a network of observatories that receiving live space weather updates from the Stereo spacecrafts. In 2013 they detected Nasa's ISEE-3/Ice spacecraft - the first step in possibly restoring the 30-year old spacecraft to operations.

Another group of German volunteers restored a historic radio telescope near Aachen. Horst Meyerdierks, an astronomer with the University of Bonn, wrote a history of the observatory (in German) for the Volkssternwarte Bonn amateur astronomy society. As West Germany rebuilt after the war it began investing in astronomical research. The 25-meter Stockert Astropelier was built in the relatively undeveloped Eifel Mountains near the Netherlands border. Over the next three decades researchers studied the Universe at the 21-cm and 11-cm wavelengths. As research shifted to larger telescopes and interferometer arrays, the Stockert Astropelier was sold to a private company that tried converting the grounds into a golf course and the observatory into a venue for rock concerts. Volunteers at Förderverein Astropeiler Stockert convinced the lottery-funded North-Rhine Westphalia Foundation to buy the observatory. The foundation restored the structures, letting the Förderverein Astropeiler Stockert  restore the telescope’s control systems and modernize the instruments. Now a UNESCO astronomical heritage site, the Stockert Astropelier conducts pulsar observations for amateur astronomers and hosts student programs to foster science education. Its Jugend forscht, or Young Scientist, project lets local high school students conduct research based on radio observations of the Moon, the Milky Way, and other objects.

Amateurs are restoring several other old radio telescopes: