TRAPPIST-1 is a red dwarf star located about 40 light years away that hosts seven Earth sized rocky planets, with at least three orbiting in the habitable zone where liquid water could potentially exist. This makes it one of the most Solar System like exoplanet systems discovered, with TRAPPIST-1e considered among the best potentially habitable exoplanets. The system's proximity and multiple potentially habitable worlds make it an ideal target for searching for technological civilisations.
The research team conducted their search using the Five hundred metre Aperture Spherical Telescope (FAST) to exploit its unprecedented sensitivity. The observations consisted of five independent L-band pointings, each with a 20 minute integration, for a total time of 1.67 hours. The frequency coverage spanned 1.05 to 1.45GHz with a spectral resolution of ~7.5Hz allowing them to detect extremely weak radio signals that might indicate alien technology.
The team led by Guang-Yuan Song from the Dezhou University in China looked for very precise radio frequencies that slowly changed over time due to planetary motion. Such signals would be virtually impossible to produce naturally and would strongly suggest artificial origin from an advanced civilisation. Based on the configuration of FAST, the researchers had the ability to detect radio signals as weak as 2.04×10^10 watts. This means they were able to detect fainter signals than any previous studies. If there were aliens transmitting radio signals regularly on a specific frequency, this study would be more likely to find them than earlier attempts.
Alas, the search found no convincing evidence of alien technology. However, rather than being disappointing, this result still provides valuable scientific information. It places upper limits on the presence of certain types of alien transmitters in the TRAPPIST-1 system and demonstrates the remarkable capabilities of modern SETI searches.
It may be some years or even decades before we can completely rule out life in the TRAPPIST-1 system but at least for now, it remains a compelling target for future SETI efforts. The team plans to expand their search to look for other types of signals, including periodic or transient transmissions that might be missed by current methods.
The search for extraterrestrial intelligence remains one of our most profound scientific endeavours, with the potential to fundamentally transform our understanding of our place in the universe. As we continue to peer out into space with ever greater precision, we’re not just looking for aliens, we’re taking the first steps toward what may be the most significant moment in human history.
Source : A Deep SETI Search for Technosignatures in the TRAPPIST-1 System with FAST