A new preprint study says that US and Chinese scientists have found radio signals emanating from a system with an Earth-like planet that meet the initial expectations for having been generated by intelligent life.
The narrowband signal was picked up by China’s massive Five-hundred-meter Aperture Spherical radio Telescope (FAST), the world’s largest radio telescope, nicknamed “Sky Eye.”
According to the South China Morning Post (SCMP), the signal was received between November 2020 and September 2021 and came from the direction of Kepler-438, a red dwarf star 473 light-years from Earth orbited by an Earth-like planet that was discovered by humans in 2015. The name comes from the Kepler satellite used to detect it. The rocky planet Kepler-438b is located in the star’s “Goldilocks zone,” where the temperature from the star is expected to allow liquid water to exist, but was found to be receiving massive doses of radiation that likely make it uninhabitable.
Chinese scientists at FAST were looking specifically for such signals, which are of the same type used by humans for radio communications and which cannot be produced by any natural astrophysical process, unlike other types of radio waves.
Based on the length of time the signal was observed and some subtle changes in its frequency associated with orbital movement, the scientists said they were able to exclude a possible human source for the signal. It also could not have been a human satellite or deep space probe, since none were in the viewing area at the time.
All that is to say that the scientists find the signal “meaningful,” but require much more research before it can be definitively said to have been produced by intelligent extraterrestrials. FAST is preparing additional observations of Kepler-438, with the project’s lead scientist telling Chinese media that even if it turns out to be “some noise,” it will still be extremely useful to study.
This isn’t the first such signal received by human observers on a Search for Extraterrestrial Intelligence (SETI) mission, though: in 1977, Ohio State University’s “Big Ear” radio telescope recorded a 72-second high intensity burst of radio signals originating from the constellation Sagittarius, which occurred along radio frequencies scientists at the time believed would be the most likely for aliens to try and communicate on. Known as the “Wow!” signal because of the operator’s written reaction, it has never been observed again since.
However, last month, a paper published in the International Journal of Astrobiology by a scientist at the UK’s Cambridge University identified a sun-like star within the area of the sky observed by the Big Ear when it received the Wow! Signal, noting it should be studied further for Earth-like planets that could have been the source of the signal.