we're not saying it's aliens ... (because it's probably not)

China's search for alien life turns up something suspicious — but there's a catch

“If I had to bet my next month’s paycheck on what this is, it’s interference from satellites.”

Xinhua News Agency/Xinhua News Agency/Getty Images

The world’s largest radio telescope dish has reportedly picked up peculiar radio signals from space — but the details of the reports remain murky.

Astronomers poring over FAST data from 2019 found two sets of suspicious signals. FAST — short for Five-hundred-meter Aperture Spherical Telescope — is the world’s largest radio observatory. It’s nestled in the misty mountains of Guizhou province in southwestern China.

And while it has many goals, one of the big ones? The ongoing search for extraterrestrial intelligence. But no one is calling these signals aliens ... yet. In fact, the story itself is a bit of a winding path.

What’s new — Having come online in the last several years, FAST (known in Mandarin as Tianyan, which translates to “heaven’s eye”) is a larger counterpart to the famed Arecibo radio telescope in Puerto Rico, which closed in 2020 after experiencing structural damage.

In addition to the two signals from 2019, the telescope picked up a different signal from the direction of a system known to have an exoplanet earlier in 2022. But the reports on those signals come from a June 14 Science and Technology Daily report that was deleted from the outlet’s site but remains posted on WeChat, a Chinese social media app. (The outlet is the official newspaper of China’s science ministry.)

And so far, those are the only reports — no preprints or published studies have been released on the mystery signals.

The feed cabin of FAST. Xinhua News Agency/Xinhua News Agency/Getty Images

So like, is it aliens? — It is true that FAST’s size — true to its English name, half a kilometer across — makes it particularly appealing to alien hunters. “If you’re looking for a weak signal, it really helps to have a big antenna,” Seth Shostak, an astronomer with the SETI Institute, tells Inverse.

Zhang Tongjie, an astronomer at Beijing Normal University, told the Science and Technology Daily that they hadn’t ruled out the possibility the signals were human and (comparatively) normal in origin — for instance, picking up communications from transmission towers or satellites in our orbit.

“If I had to bet my next month’s paycheck on what this is, it’s interference from satellites,” says Shostak. “It could be E.T., which would be an astounding result, of course — but until they’ve at least ruled out the number one cause of signals picked up in SETI searchers, I would not recommend that they fly to Stockholm awaiting a prize.”

What’s next — If it does turn out to be human-made interference, then it’s more reason to build telescopes in places where they aren’t continually bombarded by human communication: the far side of the Moon, for instance.

But suppose it isn’t interference at all. Suppose it did come from far beyond Earth’s atmosphere.

The next steps would be for FAST’s astronomers to publish something, pinpointing where FAST’s signals came from in the sky. That way, other astronomers from around the world could double-check their work.

“You wouldn’t believe it if it were only found with one instrument,” says Shostak.

Even if it is real, then, it’s not necessarily aliens. Radio astronomers often find new kinds of signals that turn out to have very natural, if fascinating, explanations.

When pulsars were first discovered in the 1960s, radio astronomer Jocelyn Bell Burnell at the Interplanetary Scintillation Array didn’t know what the radio telescope had detected, and jokingly labeled the signals “LGM,” short for “little green men.” More recently, astronomers have been picking up so-called fast radio bursts, intense flashes whose origins remain a mystery to astronomers.

Beneath all of that, there’s a slim chance that astronomers may have found something. But it’s a very slim chance indeed. “In SETI, there are a lot of false alarms,” says Shostak.