Researchers from the Breakthrough Listen project conducted a targeted search for artificial radio signals in the LHS 1140 star system. The focus came after scientists discovered that the rocky exoplanet LHS 1140 b has a tenuous helium atmosphere, making it one of the most promising «super-Earths» for astrobiology. Using archival data from the 100-meter Green Bank Telescope (GBT), the team scanned frequencies between 1 and 12 GHz over 2023–2024. They applied the standard ABACAD scheme: alternating five-minute sessions pointing at the target star and adjacent sky areas to filter out Earth-based interference.
The instrument recorded 421,787 signal candidates that exceeded the signal-to-noise threshold. After rigorous filtering — discarding anything that was simultaneously detected at both the target and off-axis positions — only seven events remained, all in the L-band (the noisiest due to terrestrial radiation). A detailed analysis confirmed these signals bore morphological similarities to known types of radio-frequency interference, meaning no technological markers from an extraterrestrial civilization were found.
While the absence of signals is a negative result, it is scientifically valuable. The researchers calculated the minimum effective isotropically radiated power (EIRP) that their system could detect, establishing a threshold of 300 gigawatts. This means that if a continuous narrowband radio transmitter exists in the LHS 1140 system, its energy output does not exceed this value — otherwise, it would have been detected. For context, all of Earth’s cellular communication radiates about 3 GW, while the famous Arecibo planetary radar had a power of around 20 TW. The study also underscores the astrobiological potential of LHS 1140 b and sets a template for systematically checking other exoplanets with recently discovered atmospheres. Future observations of LHS 1140 are planned with the Allen Telescope Array, which should increase sensitivity and expand the frequency coverage
About the Author
