China starts building world's largest fully steerable radio telescope

120-meter colossus expected to be online in 2028 – around the same time the Square Kilometer Array

A 120-meter diameter radio telescope is under construction in China and, once built, will be the world’s largest fully steerable device of its kind, according to the Chinese Academy of Science (CAS).

The purpose of the telescope is to help scientists better understand planets and asteroids, according to CAS.

The ‘scope will receive electromagnetic waves from celestial bodies and send its own energy into the heavens to allow accurate measurement of distances Earth and other planets.

Other radio telescopes with this capability include the defunct Arecibo Observatory in Puerto Rico, NASA's Goldstone Deep Space Communications Complex, and The Very Large Array (VLA) in New Mexico.

According to CAS, the radio telescope's site in northeast China's Huadian, Jilin was chosen back in May, and preliminary work has already begun. Part of its foundations have been completed and the installation, adjustment and testing of the telescope are expected to be completed in 2028.

That date coincides with projected completion dates for the Square Kilometer Array Observatory (SKAO). Some elements are already in operation, but the end of construction won't happen until 2028 or 2029.

While the Jilin telescope is a significantly large single device, the SKAO is an ensemble of over 130,000 antennas in Australia, plus another 200 in South Africa. As its name suggests, its dishes covers a total area of one square kilometer.

The Five-hundred-meter Aperture Spherical Telescope (FAST), located in China, is currently the world's largest single-dish radio telescope. It was completed in 2016, but extensive testing and calibration meant it only began operations in 2020.

FAST's 500-meter dish, while larger than the forthcoming Jilin radio telescope, is not fully steerable. The dish is located in a natural sinkhole, which gives it a mostly fixed orientation. It is designed to operate using a technique known as active surface control. It can be adjusted using a set of movable panels that allow for some flexibility in observing different regions of the sky.

Unlike the 305-meter Arecibo Observatory, which was a radar-based facility, FAST is designed primarily for radio astronomy – including studying cosmic objects like pulsars, galaxies, and black holes. Its dish allows it to collect incredibly weak radio signals from deep space.

Both the Green Bank Telescope in West Virginia and The Effelsberg Radio Telescope in Germany are fully steerable and have dish diameters of 100 meters.

The CAS revealed China is currently building smaller but fully steerable radio telescopes in locations such as the Changbai Mountain Protection and Development Zone of Jilin, Xigaze of Xizang Autonomous Region, and Qitai of Xinjiang Uygur Autonomous Region. ®