Inside China's Supermassive Alien-Searching Radio Dish

This article originally appeared on Motherboard.

The enormous bowl-shaped metal structure bears a resemblance to a hot pot dish or a wok.

"It looks magnificent. I've never seen such a big iron pan," said Mr. Fu, a 60-year-old military supply company worker standing on a slick wooden viewing platform overlooking the Five hundred metre Aperture Spherical Telescope, aka FAST, in the heart of rural China's southwest Guizhou province.

"It really lives up to its reputation," he added, as spitty rain flecked his glasses.

Mr. Fu was one of around 50 umbrella-wielding tourists ogling FAST one day last May. The dish was designed to help explore and map space, and to listen for messages from extraterrestrial life, as China's space ambitions continue to crank up.

"I'd like to ask aliens what their planet is like," said Mr. Fu, wiping his glasses to get a better view of the dish. "But I can't begin to imagine what they actually look like."

Nearby, Liu Qingwen, a 10-year-old boy from Guiyang, Guizhou's capital, was less keen on having an intergalactic natter. "I wouldn't like to talk to aliens," Liu said shyly. "They are a threat to humans."

According to the astronomical museum displays, the final metal panel was set into FAST in early July 2016, marking the end of construction (though its completion was officially announced the following September). The radio telescope is still a few years from being fully operational, but the scale of this dramatic structure has already captured imaginations globally. At 500 metres wide it is the biggest radio telescope in the world, far bigger than the next largest: the 305 metre-wide Arecibo Observatory, belonging to the US and based in Puerto Rico.

FAST is an intriguing sight. It took around five years to build at a state media-reported cost of $180 million, though it has been speculated that the real cost of the telescope was higher. To access it you pass local farmers tugging cattle along roads in Pingtang County, a poor, rural area in Guizhou featuring stunningly lush natural green beauty. The tarmac is newly-laid to service the dish, and flanked by under-construction, spacecraft-themed gas stations and tourist centers.

Controversially, around 9,000 locals were relocated as a resident-free zone was created around FAST to stop interference from digital devices. All visitors are frisked for digital equipment before entering the FAST zone, which was chosen due to its relatively low population and the formation of its mountains, similar to other ultra-sensitive astronomical sites like West Virginia's Green Bank Telescope, where cell phones and radios are likewise banned.

A custodian working near FAST's ticket office said that local attitudes toward the forced relocations tended to vary between generations. Many young locals welcomed new job prospects brought on by the dish, according to the cleaner, while many members of older generations mourned having to leave long-established family homes.

Across wider China, however, the alien-searching aspect of FAST has caused much excitement, stoked by a huge astronomical museum near the structure that features statues of bulbous-headed humanoid aliens. "Aliens have probably been messaging us for decades, but we missed them," and similar statements abound on displays in the museum.

But when FAST is finally fully operational, how likely is it that the dish will indeed start intercepting messages from aliens?

The "father" of the dish, Nan Rendong, FAST's chief scientist, has not been shy about hyping his creation. "As the world's largest single aperture telescope located at an extremely radio-quiet site, its scientific impact on astronomy will be extraordinary, and it will certainly revolutionize other areas of the natural sciences," he told Chinese state media in 2016.

Experts largely agree that Nan is justified in making such statements. The dish's creators have set a target of discovering 1,000 new pulsars; studying these spinning stars can shed light on exoplanets (planets outside the solar system), distances in space, and entities like black holes, among other cosmic phenomena. If achieved, this would represent a huge haul added to the estimated 2,500 pulsars already discovered.

"Every time there's an increase in the number of known pulsars there are new phenomena discovered," Dick Manchester, a radio astronomer at Australia's Commonwealth Scientific and Industrial Research Organisation, told Motherboard. "That goal of 1,000 newly discovered pulsars is realistic. Doubling the number of pulsars–or in that ballpark–is certain to turn up a lot of unexpected objects."

Manchester said that the discovery of a pulsar orbiting a black hole would be hugely significant, allowing insight into these mysterious entities. Pulsar monitoring could also potentially help confirm the existence and explain the nature of dark matter, unobservable matter that many scientists believe makes up most of the universe but nonetheless remains unconfirmed. FAST will also probe gravitational waves, "ripples" through spacetime caused by massive accelerating objects. The dish will also scan the skies for fast-radio bursts, short radio pulses of unknown origin that have intrigued astronomers.

But in terms of FAST's abilities, many people are most giddy about the prospect of the dish receiving a message from aliens. Peng Bo, head of China's National Astronomical Observation, has claimed that "FAST's potential to discover an alien civilization will be five to ten times that of current equipment, as it can see farther and darker planets."

Douglas Vakoch, president of METI International, an organisation that attempts to make contact with alien life, told Motherboard that FAST's efforts in this field will not be limited to passively waiting for "Well, hello there!" radio messages from Martians. The dish will aid efforts to map the distribution of hydrogen throughout the Milky Way and other nearby galaxies, with hydrogen changing states being an indicator of planets that could potentially sustain life.

Vakoch added that due to the limited extent of current radio technology, any radio signals from alien civilizations detected by the dish would have to be strong and deliberately sent with contact in mind, rather than randomly fired out from radio or TV equivalents.

"We'd only be able to find the sort of signals that FAST will be looking for: narrow band signals, something that would have a lot of energy put into a carrier," he said. "An interstellar beacon saying: We are here."

It's all very well aiming a massive dish at the sky and listening, but if life indeed does exist beyond Earth, is it intelligent according to the definitions we understand? Would it have the technology to send a radio message to us? Would it event want to? And why?

So many factors would have to align for FAST to receive a meaningful message from an extraterrestrial civilization. Still, many scientists believe that the probability of life existing beyond Earth is high. Manchester said that it is "virtually guaranteed."

"The probability that the development on Earth was a completely unique event is very low. There doesn't seem anything terribly special about the way life evolved here. But the distances in space are so immense, the probability of us being able to communicate with them [back and forth] are so tiny as to be completely improbable."

It's not just the makers of FAST who believe it's worth listening. Russian billionaire Yuri Milner, for one, has spent $100 million on Breakthrough Listen, an interstellar exploration project also involving listening for alien radio signals.

Manchester and Vakoch both suggested that if intelligent life is out there, it would be extremely likely to have technology far more advanced than ours. As such, it would likely be able to send radio signals easily, and perhaps already be aware of life on Earth.

"Our civilization has only been evolving for tens of thousands of years," said Manchester. "Other civilizations could have had billions of years to evolve. It's virtually certain that any other civilization we detect would be enormously more advanced than we are. Our history in terms of stellar evolution is absolutely tiny."

According to Vakoch, if such a civilization were just 300 years ahead of humans–the tiniest fleck on an evolutionary timescale–in terms of technology development, their communication abilities would be so advanced as to be almost incomprehensible to us.

So, what are the odds of these potentially super-advanced aliens making contact through FAST? Vakoch said that although it feels like a long shot, many previous astronomical discoveries also once seemed improbable.

For example, after pulsars were discovered in 1967 they were nicknamed LGM (short for "little green men") because astronomers had never before observed anything not created by humans that pulsed with such regularity. The first exoplanet was discovered in 1992, and now many exoplanets that are potentially able to sustain life have been documented. FAST is almost certain to add richly to the timeline of astronomy.

"We should be optimistic in our search. Everything we're discovering makes it seem more likely that there could be life out there," said Vakoch. "But we still have not got one single piece of direct evidence that there is even bacteria in space."

A 46-year-old tourist who introduced himself to me in FAST's astronomical museum as Mr Yu was more resolute.

"I think the dish will find them," he said, standing near a cheery display depicting grinning grey aliens. "FAST is a breakthrough for exploration of the universe. I'd give aliens my greetings, then discuss the origin of human life and evolution with them. I want to know where we are from, and where we are going.