FAST Telescope Searches for Alien Signals Near Comet 3I/ATLAS

The Breakthrough Listen initiative has found no evidence of extraterrestrial intelligence in its observations of the interstellar object 3I/ATLAS, despite a focused search for technosignatures. Observations were conducted using the Allen Telescope Array beginning in early July 2025, shortly after the object’s discovery on July 1, 2025.

The search covered a frequency range of 1 to 9 GHz, achieving sensitivities between 10 and 110 Watts equivalent isotropic radiated power (EIRP). A detailed analysis of the data is currently undergoing peer review, with a preprint available for examination.

3I/ATLAS, the third interstellar object detected to date, exhibited an unusual brightening near its closest approach to Earth, becoming brighter faster than any known comet. This anomaly, coupled with the relative rarity of interstellar objects, prompted the thorough investigation by Breakthrough Listen, motivated by the possibility that such objects could be interstellar probes – a potential technosignature, as suggested in prior research (Freitas & Valdes 1985. Davenport et al. 2025).

Researchers identified a diagonal stripe in radio spectrograms from the Allen Telescope Array, initially appearing as a potential signal. However, this feature was similarly present in off-target observations and was attributed to local radio interference from human sources, effectively ruling it out as a candidate technosignature (Sheikh et al. 2025).

Observations continued through the object’s closest approach to Earth. As of December 19, 2025, no technosignatures had been detected. A recent report, published March 12, 2026, notes that 3I/ATLAS is fading, and highlights 22 mysterious anomalies observed during its passage. Further study of the object is ongoing, as it continues to move away from Earth.

The Allen Telescope Array, used in the search, is operated by the SETI Institute and is dedicated to the search for extraterrestrial intelligence. The Breakthrough Listen project utilizes this and other facilities worldwide in its ongoing efforts to detect signs of life beyond Earth.