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China's Massive Telescope is the Next Great SETI Hope

FAST,SETI,China
Keith Cooper
Matt Morgantini
July 13, 202006:07 AM
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In Close Encounters of the Third Kind, first contact takes place at the bottom of a mountain — Devil’s Tower, Wyoming.

That was fiction, but in real life, it’s very possible that first contact will take place instead at the bottom of a ring of mountains, half the world away, in a remote province of south-west China.

Embedded within a deep circular depression formed by a karst region of towering limestone mountains, the giant Five-hundred-meter Aperture Spherical Telescope (FAST) is the world’s most powerful radio telescope. It’s also something else: the next great hope in SETI, the search for extraterrestrial intelligence.

Thanks to FAST, China is turning into a major player in the world of SETI — by the end of this decade, it could be the major player.

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“China has been very interested in the question, ‘are we alone?’ For a long time,” says Dan Werthimer of the University of California, Berkeley. “But until recently there have been very few people working on SETI in China.”

Now it’s full speed ahead. FAST’s visionary architect, the late astronomer Nan Rendong, who passed away in 2017, was keenly interested in SETI. So too is Zhang Tong-Jie, who is a Professor of Astronomy at Beijing Normal University and leader of FAST’s SETI program. 

Yet China’s ascendance in the world of SETI has prompted much hand-wringing among some commentators in the West, expressing concerns that the government in Beijing may choose to keep the discovery of an extraterrestrial signal, and any information learned from it, a secret. Worse still, say the commentators, China could potentially act unilaterally and be the point of first contact with an alien society.

Yet when I asked Zhang Tong-Jie about what China’s response would be, were FAST to detect a signal, he was very clear.

“We and our collaborators use the International Academy of Astronautics SETI Post Detection Protocol, which calls for independent verification [of any signal] and for all information to be shared with the public,” he says.

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The Post Detection Protocol — often referred to as the First SETI Protocol (a second protocol, which would have touched on rules regarding sending our own messages to space, stalled in committee meetings) — is a general guide for astronomers to follow should they detect a candidate SETI signal.

Critics might point out that the protocol is not legally binding. However, there’s a safeguard inherently built in to how astronomers conduct SETI and confirm whether a signal is just terrestrial interference, or whether it really is coming from the stars. Another radio telescope, in another part of the world, has to be alerted, and if the signal really is just local interference, or even a satellite passing overhead, the second telescope shouldn’t be able to detect it. Besides, as the Earth rotates, the source of the signal will inevitably set below the horizon, so if astronomers want to keep tracking it, telescopes in other parts of the world need to take over.

Furthermore, the groundwork is already in place for this collaboration to happen. SETI on FAST is a pleasingly multinational affair, and several recent papers summarizing FAST’s SETI abilities and early results feature a healthy mix of Chinese and US scientists, the latter being led by Werthimer and his group at Berkeley. 

Throughout its 60-year history, SETI has shown an ability to transcend political boundaries. In the 1960s and 1970s, for example, Soviet and US scientists were able to come together, trade ideas, and advance the search for ET. At the same time, Werthimer was beginning a journey that would be the start of forging a lasting relationship with scientists from the world’s other superpower, China.

“It all started when Beijing Normal University invited me to take a sabbatical there in the late 1970s,” Werthimer tells me. “Since then there have been a lot of wonderful exchanges back and forth.”

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Those exchanges have included Werthimer’s Berkeley group hosting a steady stream of Chinese PhD students, whose input into various SETI programs has been revelatory. For instance, the most recent Chinese postgraduate to come to California, Wei Liu, has been a key player in the PANOSETI optical SETI project, while an earlier student, Zhi-Song Wei, contributed some clever machine learning techniques to improve software designed to identify candidate SETI signals from raw radio data.

As a result of this connection, scientists at the National Astronomy Observatory of China (NAOC) invited Werthimer and his team in California to build a SETI instrument for commensal use on FAST, based on their experience of building a similar instrument for use on the 305-meter Arecibo radio telescope in Puerto Rico. 

Known as SETIBurst, it piggybacks on FAST’s regular astronomical observations, listening carefully in the background should an extraterrestrial signal happen to fall into FAST’s field of view. It’s an approach that worked well on Arecibo, returning vast amounts of data that was shared among the now retired SETI@home network; Werthimer has plans to revive SETI@home, or at least something similar to it, with the data accrued from FAST.

This highlights another reason why it would be extremely difficult for the Chinese government to keep a lid on any FAST SETI detection. It’s eminently possible that a signal could remain hidden in the vast reams of data that the telescope will collect, lurking undetected for weeks or even months until it pops up after-the-fact, detected by some member of the public somewhere else in the world who has downloaded the SETI@home software (or whatever its replacement will be). 

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If an extraterrestrial signal is discovered one day, then there will be a clamor from some quarters to send a reply. Again, there are no laws, no legal requirements for any nation, organization or individual to adhere to — everybody has the freedom to send a reply. However, the most powerful transmitter that we have is Arecibo — FAST is not set up to broadcast like its Caribbean cousin. Even if it were, Zhang Tong-Jie tells me that the feeling among SETI researchers in China is that transmitting our own messages into space is inherently dangerous.

“My research group, and almost all SETI researchers on the planet think that deliberately transmitting messages to ET is risky,” he says. “Our emerging civilisation is very young —

We knowvery littleabout whatmight be out there.”

 

Zhang’s countryman, science-fiction novelist Liu Cixin, warned of the ‘dark forest.’ Like hunters in the forest, extraterrestrial civilisations may be staying quiet, waiting for unaware young civilisations to go blundering loudly through the forest of stars. Echoing this language, Zhang tells me that in his opinion, “Transmitting deliberately is similar to shouting in the forest without knowing if there are lions and tigers there. Risky decisions such as these should have an extremely broad international community weigh the potential risks and benefits.”

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So, if Zhang has any say in the matter, China won’t be a rogue nation when it comes to SETI. The fear that China will be secretive when it comes to SETI, and act only to serve their own interests, seems to be paranoia born of the current political tensions between the US and China. Or, perhaps, there is some angst about the US ceding its superiority in the field to China, but such worries miss the big point: that the entire global SETI community can take advantage of this marvelous telescope that China has built. When it comes to the odds of finding that we are not alone, that can only be a good thing.

Keith Cooper
Matt Morgantini
July 13, 202006:07 AM