How noisy Chinese tourists may be drowning out interstellar signals at the world's biggest telescope

• Stephen Chen, South China Morning Post

• Aug. 24, 2017, 9:42 PM

Five-hundred-metre Aperture Spherical Radio Telescope (FAST).Reuters

So many Chinese tourists have been swarming to the site of the world's biggest radio telescope that they may affect the giant dish from performing its job properly, scientists say.

In just the first half of the year, nearly four million tourists visited Fast, the 500-metre aperture spherical telescope, in Pingtang county, Guizhou province, according to government statistics released this month.

During the Dragon Boat Festival on May 30, about 220,000 people crowded at the site in the remote mountains of southwest China for a glimpse of the giant dish.

The day's tourist attendance was almost twice that of visits to the Arecibo observatory – the world's second biggest such telescope located in Puerto Rico – in an entire year.

The Fast radio telescope was built to help scientists better understand the universe, and its key missions include receiving and recording pulsar and interstellar signals from extraterrestrial sources.

Doing so requires the dish to be situated in a very quiet, isolated area, but the amount of tourism it has attracted is changing its environment.

A county tourism official said Fast was expected to draw a total of 10 million tourists, mostly domestic, this year.

"That will be as many as the tourists to the Great Wall in Beijing. Here we have a new wonder of the world," the official said.

For the first half of the year, the tourists brought the county a revenue of 4.6 billion yuan (HK$5.4 billion), a 40% increase from the same period last year, according to a Guizhou Dailyreport this month.

Construction of two expressways will start in the coming few months, to connect Pingtang to the provincial capital of Guiyang. The eight-lane motorways will take tourists from an international airport to the Fast site within an hour, the report said.

Tian Renfei, party secretary of Kedu, the town closest to the facility, told local media that the town's targeted annual GDP growth rate for the years to come was 50%.

The small 700-year-old town has opened 46 hotels and over 100 restaurants to cope with the incoming tourism, with more being built.

Beijing Planetarium director Zhu Jin, who recently visited the telescope site, said the tourism boom was fueled by the public's enthusiasm for advanced scientific facilities.The FAST is seen under construction among the mountains in Pingtang county, Guizhou province, China, November 26, 2015.REUTERS/Stringer

This was "definitely a good thing" for China, given its ambition to become a research superpower. But the rapid increase in human activity in the previously isolated region – a key reason the telescope was built there – would inevitably increase electromagnetic pollution, he said.

"It can affect the telescope's observation," Zhu said. "There may not be an easy solution and may require compromise from both sides."

Scientists working at the telescope site have vented their frustrations in private.

They were particularly worried about the impact of new platforms built near the site to drive ticket sales to curious sightseers, according to researchers close to the project.

But the astronomers hesitate to confront the local authorities in public.

"We understand their urge to develop the economy and get rid of poverty [in the impoverished region]," said a researcher who asked not to be named because of the sensitivity of the matter.

The Fast project officer in Beijing could not be reached for comment.

The 1.2-billion yuan telescope, which saw construction completed last year, is China's costliest astronomy project.

Its giant dish has allowed researchers to listen to faint signals at least three times farther away than when using the Arecibo.

The unprecedented sensitivity might lead to breakthrough discoveries on a wide range of subjects from pulsar to dark energy, which can help people better understand the origins of the universe.

Tourists from China wave as they arrive on a cruise ship in the northern Taiwan port of Keelung. Reuters/Nicky Loh

Last December, a collaboration agreement teamed the Fast telescope with Breakthrough Listen, a US$100-million programme funded by Russian entrepreneur Yuri Milner, in searching for signals produced by intelligent life in the universe.

Fast is presently being tested and calibrated. When it will start formal observation has not been revealed.

Since the Fast dish was pointed at the sky, it might be able to avoid most of the electromagnetic disturbance generated from the increased human traffic, according to a researcher studying radio noise at the Shanghai Jiaotong University's department of electronic engineering.

The core facility was also surrounded by a 5km buffer zone for a complete radio blackout, said the scientist, who asked not to be named. Within the zone, no electronic devices, such as smartphones or digital cameras, are allowed to be used without a permit from the authorities.

"But 10 million tourists a year may have exceeded the telescope designers' wildest guess. They may need to launch a new round of investigation to assess the exact impact," the scientist said.