China’s new radio telescope will have dangerous solar eruptions in its gaze

Construction of the world’s largest circular radio telescope array aimed at the sun – located in southwest China – is expected to be finished by the end of the year, according to the project’s supervisor.

The Daocheng Solar Radio Telescope (DSRT) is being built at a site high up on the Tibetan Plateau and will have 313 dishes, each of them 6 metres (19.7 feet) across.

It will be used to study dangerous solar eruptions known as coronal mass ejections – when magnetised plasma escapes from the sun’s upper atmosphere and propagates in the interplanetary space.

These eruptions are believed to have caused major geomagnetic storms on Earth, including the Carrington Event in 1859 during which telegraph stations all over Europe and North America failed.

The DSRT will be used alongside the Mingantu interplanetary scintillation telescope – also solar and currently being assembled on the grasslands of Inner Mongolia to the north – and will put China at the forefront of space weather research.

There is a key difference in how they will work. The Mingantu telescope aims to monitor the sun in an indirect way, by detecting how radio signals from deep space are scattered by solar winds. But the DSRT will take direct images of the sun in radio waves with a frequency range between 150 and 450 megahertz.

“The DSRT will be the world’s largest circular array for solar radio imaging, and enable more accurate observation of coronal mass ejections,” Wu Junwei from the National Space Science Centre, who is supervising the project on-site, told the official China News Service last week.

Wu said good progress had been made on the building work and it should be completed by the end of 2022.

The telescope’s hundreds of parabolic, or dish, antennas will be equally spaced around a 3.14km (1.95-mile) circle. A 100-metre tower stands in the centre and will have a transmitter mounted on top to help with accurate calibration of the array.

An algorithm has been developed to optimise the array’s configuration which, when tested on 16 of the antennas, was found to work well, scientists involved in the project wrote in Publications of the Astronomical Society of the Pacific in July last year.

In addition to research, the observatory will also be open to the public and used for science outreach, Wu told China News Service.

It will be part of a planned 7 billion yuan (US$1.04 billion) astronomy and archaeology park in Daocheng, a county in the west of Sichuan province. Announcing the project on Wednesday last week, Garze prefecture officials said they aimed to make it a world-class tourist destination.

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Daocheng is known for its snow-capped mountains and lakes as well as Tibetan culture and is home to the world’s highest-altitude civilian airport at 4,411 metres.

A new cosmic ray observatory – known as the Large High-Altitude Air Shower Observatory – has just been completed in the county. The Piluo archaeological site was also recently discovered in Daocheng and is said to be China’s best preserved site from the Paleolithic period.