The Future of American Radio Astronomy Now Depends on China

China's FAST telescope sits nestled in a mountainside.
Xinhua / Ou Dongqu via Getty

In the hills of China’s Guizhou province, a natural rock bowl cradles the world’s largest single-dish radio telescope. This instrument, called FAST—the Five-Hundred-Meter Aperture Spherical Radio Telescope—is, as its name suggests, 500 meters, or about 1,640 feet, across, a size that helps scientists detect more distant and fainter objects. And in late March, FAST began accepting scientific proposals from international astronomers.

The timing couldn’t have been better. In August 2020, a support cable on the next-largest telescope of this sort—part of the Arecibo Observatory in Puerto Rico, the only telescope of its class in the United States—snapped. Another cable followed a few months later. Then, in December, with a puff of dust, the massive instrument platform that hung above the telescope crashed down, destroying the 305-meter dish.

That loss left astronomers like James Cordes of Cornell University scrambling. Cordes studies strange objects called pulsars, spinning cores that remain when giant stars explode at the end of their life. The remnants, if oriented the right way, beam radio waves at Earth, like very distant lighthouses. With Arecibo off the table, Cordes—and many other astronomers who used Arecibo to study stars’ evolution and discover distant galaxies—had one less option, and no option as sensitive, with which to do his work.

Recommended Reading

Until, that is, FAST opened to astronomers, for the first time since its construction finished in 2016. After that initial completion, scientists and engineers spent years commissioning it and bringing it up to full scientific operation. They deemed it ready for proposals from would-be users in China early last year. “The timeline was very tight, and it was extremely difficult to get everything ready for opening to the world [at] that time,” Keping Qiu, a professor in the School of Astronomy and Space Science at Nanjing University, wrote in an email to Undark. Qiu leads the committee that will evaluate the incoming ideas and added, “The FAST group worked very hard over the past year, and now the telescope is making the step forward” by opening up to the world.

If the international researchers’ ideas pass muster, those scientists will get approximately 10 percent of the telescope’s time, and the remaining 90 percent will go to Chinese scientists. “We expect that FAST would not only take the place of Arecibo in supporting astronomers doing good science in relevant research areas,” Qiu said, “but also make breakthroughs and open new windows for research in radio astronomy.”

This kind of shared use mirrors the way many large observatories around the world work, in which an Open Skies policy lets anyone from anywhere compete for observing time. It also reflects China’s broader efforts to host world-class facilities that foreign researchers envy—a flex of global muscle. But scientific tensions and suspicions currently run high between the U.S. and China: American researchers have faced increasing censure for taking undisclosed money from China, the U.S. fears its rival would like to steal intellectual property, and concrete restrictions exist for certain space scientists who’d like to work across these particular borders. Current federal law in the U.S., for instance, severely limits NASA and its scientists from working on projects with China and its scientists. Collaboration, it turns out, rarely comes without complication.

But American and Chinese astronomers both hope this particular opportunity will nevertheless work smoothly for both sides. “Observatories generally feel that they benefit by having an influx. The more people from more places that come through and use the telescope,” Cordes says, “it kind of lifts all boats, that rising tide.”


Cordes and colleagues are hoping to use FAST at some point for work on a project called NANOGrav (short for North American Nanohertz Observatory for Gravitational Waves). The group watches to see if pulsars’ pulses, which are emitted like clockwork, arrive delayed or early. In aggregate, that messy timetable indicates that ripples in the fabric of the universe, called gravitational waves, are stretching or squishing said fabric. But to get the job done, astronomers must spy every couple of weeks on a network of pulsars, for which they had previously used both Arecibo and America’s next-largest instrument, the Robert C. Byrd Green Bank Telescope, in West Virginia. When Arecibo collapsed, the team was left looking for a new instrument.

Maura McLaughlin, a senior researcher with NANOGrav and a professor of physics and astronomy at West Virginia University, is also planning to suggest that the FAST telescope peer at rotating radio transients, or RRATs—essentially pulsars that just blip on occasion. Her research group discovered a few hard-to-detect RRATs using Arecibo. Because the team can’t follow up using that instrument, FAST is now “really the only telescope that’s possible,” McLaughlin says.

Qiu expects to see proposals about topics as varied as the complicated chemistry between stars and powerful bursts of radio waves whose origin remains a mystery. Loren Anderson, also a professor of physics and astronomy at WVU, is interested in what FAST could reveal about how big stars affect the space around them and inhibit new-star formation, research that can help scientists understand our galaxy’s evolution. “When they began FAST, Arecibo was operating in great health,” he says. “And now it’s dead. And so I think that makes FAST a more attractive instrument. It is now unique in the world.”

FAST will also be key to studies of neutral hydrogen gas, a fundamental building block of the universe. One FAST instrument should prove useful for that investigation. Designed and built by Australian engineers, the receiver allows FAST to observe 19 separate spots in the sky at once.

Chinese and Australian radio astronomers collaborate often—in part because they have an existing relationship through another telescope effort called the Square Kilometer Array, a project the U.S. dropped out of in 2011. Among astronomy’s most ambitious endeavors, this radio-dish array will comprise a network of thousands of dishes and up to 1 million antennas, spread across South Africa and Australia, which will together form a giant telescope.

But scientific collaboration with China can get complicated for U.S. scientists. Recent probes at the National Institutes of Health, for instance, led to the firing or resignation of dozens of people who hadn’t disclosed foreign funding or participation in foreign talent programs—and 93 percent of the investigations involved China.

A 2011 policy makes collaboration particularly difficult for some federal scientists. The legislation, colloquially called the Wolf Amendment, requires certain U.S. government agencies to consult with the FBI and notify Congress before working with China. It could limit NASA, the Office of Science and Technology Policy, and the National Space Council from working on bilateral programs or other collaborations with China.

Though the provision remains on the books, more cooperation has happened recently than in the past. In 2019, when China sent its lunar spacecraft, Chang’e-4, to the far side of the moon, one of NASA’s lunar orbiters snapped a picture of the rover after it landed. When it comes to space programs, “that’s really the greatest representation of collaboration in the last almost-decade,” says Makena Young, a research associate at the Center for Strategic and International Studies.

In Young’s view, the Wolf Amendment hurts scientific innovation, limiting the diversity of perspectives, and propels China to “compete even further with what we’re doing,” she says.

Outside of those federal restrictions and disclosure requirements, though, U.S. radio astronomers can and do work with China. Green Bank scientists, for instance, consulted on FAST’s development. McLaughlin has a National Science Foundation grant that sends her WVU students to China every summer. She worried about including that exchange in her grant request, thinking she might encounter restrictions or extra scrutiny, but that wasn’t the case. “We’ve had no issues with that at all,” she says.

China’s participation in the International Pulsar Timing Array, a global endeavor that brings together smaller-scale projects such as NANOGrav, has similarly not affected NANOGrav’s ability to get U.S. funding, according to McLaughlin. She is grateful, scientifically and personally. “Most of the Chinese colleagues that we work with really closely, we know very well,” she says. “There’s a lot of mutual trust.”

That trust may be key to the research because now a connection to Chinese facilities is necessary for some types of research. Many of the observations McLaughlin and her team would like to make, she says, can’t happen without such truly massive telescopes.


That China hosts the world’s largest telescope is not an anomaly: The country has been amping up its global scientific presence for the past couple of decades. In astronomy, for instance, the country recently launched two satellites that watch the whole sky for gamma-ray bursts, some of the brightest events in the universe; NASA’s two gamma-ray observatories are 17 and 13 years old. China also recently built a physics laboratory deep underground, where the earth above shields it and allows for pristine data collection, and the country is planning to construct a steerable radio telescope ever-so-slightly larger than Green Bank.

On the collaborative front, China plans to share samples from its Chang’e-5 lunar lander, which plopped back down to Earth in December 2020, with the international community (although U.S. policy may prevent some of that sharing).

Such infrastructure and collaboration help the progression of science itself. But they also function as political tools. Scientific prowess is not just the pursuit of pure knowledge: It’s also a form of what political scientists call soft power.

“Soft power is the ability to influence others through offering them things they want,” says Victoria Samson, the Washington office director at Secure World Foundation, a space-sustainability think tank. Sometimes, that opens avenues for collaboration in other, unrelated areas, such as trade. The general idea, Samson continues, follows the maxim “You catch more flies with honey than vinegar.”

Kevin Pollpeter, a research scientist specializing in China’s space program at CNA, a think tank that works with agencies including NASA, the National Science Foundation, and the Department of Defense, agrees with Samson’s logic. “It’s not dropping bombs on people, or threatening to,” he says. “It’s more about how it shows you can gain influence by increasing your prestige or status.” The U.S. aimed to be first on the moon, for instance, to show its strength during the Cold War. China has now made a huge telescope available after its competitor’s fell down. “It’s just one other example of their being able to provide something the U.S. cannot at this time,” Samson says.

Qiu said the primary motivation for the telescope’s opening is research-driven, and that the timing was based on when FAST, which passed technical inspection and scientific validation in early 2020, was ready for prime time. “Telescopes are built for astronomy, for science. And astronomers doing observational research wish to use telescopes all around the world, as long as the telescopes fulfill their scientific need,” he said. “But we will also be very happy to see that such an openness plays a positive role in bridging culture exchange and showcases the importance of international collaboration.”