December 17, 2025, 14:00 GMT | Beijing, China & Guizhou, China
The decades-long search for extraterrestrial intelligence (SETI) has entered a new and profoundly focused chapter, with the Earth’s most powerful radio eye now fixed intently on the most promising planetary system ever discovered beyond our own. As of this week, a dedicated team of Chinese scientists from the Beijing Normal University, the National Astronomical Observatories of China, and operating the colossal Five-hundred-meter Aperture Spherical radio Telescope (FAST) — the “China Sky Eye” — has initiated an unprecedented, systematic, and technologically advanced campaign targeting TRAPPIST-1. This ultracool dwarf star, 40 light-years away in the constellation Aquarius, hosts seven rocky planets, three of which sit squarely within the habitable zone where liquid water could exist. The effort, described by project leads as the most comprehensive and sensitive SETI investigation of the system to date, is already yielding intriguing data and methodological breakthroughs that are reshaping how the global scientific community approaches the hunt for technosignatures.
The fundamental impetus for this campaign is the unparalleled nature of the TRAPPIST-1 system. Discovered in 2016, its seven transiting Earth-sized worlds present a unique laboratory for comparative planetology and the search for life. *”TRAPPIST-1 is not merely a target; it is the target for our generation’s SETI inquiries,”* explains Dr. Li Chen, astrophysicist and principal investigator of the FAST TRAPPIST-1 Survey (FTS). “The system’s compact architecture means that if a communicative civilization exists on any of these worlds, they would have known about their neighboring planets for potentially billions of years. The interplanetary exchange of information, or even the leakage of planetary radar or communication signals, becomes a statistically more likely phenomenon there than in our own solitary inner solar system.” This perspective shifts the paradigm from searching for intentional beacons aimed at Earth—a needle-in-a-haystack proposition—to listening for the possible “background chatter” of an intra-system technological network.
The Chinese team’s campaign, which commenced in earnest in late November 2025, leverages the supreme sensitivity of the FAST telescope. With its 500-meter dish, FAST can detect extraordinarily faint radio signals, giving it a significant advantage over other facilities. The project is scanning a broad frequency range from 1 GHz to 4 GHz, a relatively “quiet” band where natural cosmic noise is minimal and which is commonly used for Earth and space-based communication. Critically, the team is not just listening for simple narrowband signals—the classic “SETI tone”—but is employing a suite of advanced analytical techniques. These include searching for wide-band pulsed signals, anomalous spectral patterns, and, most innovatively, conducting a full Stokes polarization analysis on the incoming data.
This focus on polarization is a game-changer. “Most natural astrophysical processes produce signals with specific, predictable polarization properties,” notes Professor Elena Wang, a signal processing expert on the team. “A technosignature, however, especially one designed for communication or radar, would likely exhibit a very different, complex polarization signature. By analyzing the full polarization state of every signal we detect, we have a powerful new filter to separate human-made radio frequency interference, natural cosmic sources, and, potentially, an engineered signal.” This method has already proven effective in weeding out terrestrial interference, which has plagued previous SETI efforts.
As of December 17, 2025, the team reports no definitive detection of an extraterrestrial technosignature. However, they have made several critical discoveries and identifications. Firstly, they have created the most sensitive radio flux density map of the TRAPPIST-1 system to date, establishing a new upper limit on any persistent radio emissions from the star and its environs. This in itself is a valuable astrophysical datum, constraining the star’s magnetic activity. Secondly, they have identified and cataloged over a dozen previously unmapped background quasars and radio galaxies in the field of view around TRAPPIST-1, using their polarization signatures to confirm their natural origin. This cleans the stage, removing potential false positives for future analyses.
The most talked-about aspect of the data, however, is the existence of several “signal events of interest.” These are narrowband signals that passed initial automated filters but were subsequently determined to be human satellite interference through meticulous backtracking of satellite orbits and the polarization analysis. “The fact that our pipeline flagged them, and our new methods conclusively identified them as terrestrial, is a validation of our entire approach,” Dr. Chen states. “We are listening at sensitivities never before applied to this star, and we are successfully navigating the growing jungle of Earth’s own radio emissions. This procedural rigor is what makes this campaign serious and sustainable.”
The campaign is planned in multiple phases over the coming years, synchronized with the orbital periods of the TRAPPIST-1 planets. The team aims to observe during windows when multiple planets, particularly the habitable zone worlds e, f, and g, are aligned in specific configurations, hypothetically favorable for interplanetary communication. They are also collaborating with optical astronomers to cross-reference their radio observations with any anomalous atmospheric phenomena detected via spectroscopy from the James Webb Space Telescope.
The societal and scientific implications of this focused hunt are profound. China’s decisive investment in FAST has positioned it at the forefront of both traditional astronomy and the search for extraterrestrial intelligence. This project demonstrates a mature, long-term commitment to one of humanity’s ultimate questions. Furthermore, the team has committed to a policy of transparent, rapid data sharing with international partners like the Breakthrough Listen initiative and the SETI Institute, fostering a collaborative rather than competitive global effort.
“We are under no illusion that success is guaranteed, or even likely,” concludes Professor Wang. “But for the first time, we are pointing the most sensitive instrument of its kind ever built by humanity at the most promising location for life we have ever found, using the most sophisticated filtering techniques ever deployed. We are eliminating the unknowns one by one. If there is a signal to be found from those seven worlds, we are now, truly, in a position to find it. That in itself is a monumental step forward.” As the “China Sky Eye” continues its silent, patient vigil towards Aquarius, the world watches, knowing that the hunt for our cosmic neighbors has not just continued—it has evolved, matured, and become a central pillar of 21st-century astronomical science.
