Search for Radio Signals on K2-18b Fails to Discover Alien Civilization

Exoplanet K2-18b has generated immense intrigue due to hints of potential life; however, an extensive analysis of radio signals revealed no evidence of an advanced civilization.

In 2025, Nick Madhusudan and researchers from the University of Cambridge claimed that K2-18b, located 124 light-years away, may exhibit traces of dimethyl sulfide (DMS) molecules in its atmosphere. Given that a significant amount of DMS on Earth is produced by biological processes, Madhusudan and his team suggested these signals might indicate signs of life on K2-18b.

Further observations, however, indicated that the DMS signal could be attributed to non-biological sources. Current scientific consensus holds that K2-18b is abundant in water, potentially featuring oceans or a water-laden atmosphere.

Madhusudan and fellow researchers are now exploring the possibility of extraterrestrial intelligent life on K2-18b by searching for radio signals, akin to those humans have been broadcasting since the 1960s.

Utilizing the Very Large Array Telescope in New Mexico and the MeerKAT radio telescope in South Africa, researchers observed K2-18b in multiple orbits around its star, focusing on radio frequencies similar to those emitted from Earth. They might have detected a signal from a transmitter with strength comparable to that of the now-defunct Arecibo radio telescope in Puerto Rico.

After meticulously eliminating potential terrestrial interference sources, researchers found no signals indicating that K2-18b possesses a powerful radio transmitter. Select researchers remained unavailable for comments to New Scientist regarding their findings.

“If a beacon akin to Arecibo were continuously transmitting from K2-18b, we likely would have detected it,” said Michael Garrett from the University of Manchester, UK.

“Of course, a lack of detection does not imply the absence of life; it simply restricts a specific and likely rare type of signal: a continual, relatively narrowband radio transmitter operating within the observed frequency range,” Garrett explained. “Civilizations, should they exist, might not utilize radio technology in this manner or may transmit intermittently, directionally, or at lower power levels. Furthermore, in aquatic environments, very low-frequency radio waves could be more common.”

Garrett posits that while alien water worlds may support simple life forms, the absence of exposed land could complicate the evolution of advanced intelligent life capable of developing technology. “The pathway to establishing complex infrastructure could vastly differ from what we have experienced on Earth.”

Explore Mysteries of the Universe in Cheshire, England

Join some of science’s brightest minds for a weekend exploration of the universe’s mysteries. The program includes a tour of the iconic Lovell Telescope.