74 million narrowband signals were initially flagged across 1 to 9 gigahertz, but filtering out human interference and matching the object's motion cut that to about 200, all traced to Earth-based or orbital technology.
The results place upper limits of roughly 10 to 110 watts on any transmitter on or near 3I/ATLAS over the observed frequencies, reinforcing other evidence that the object is a natural comet-like body.
3I/ATLAS, discovered in July 2025, is only the third confirmed interstellar object seen in the Solar System, making it a rare target for both planetary science and technosignature searches.
Observations began less than a day after the object's announcement, highlighting the array's rapid-response capability as more interstellar visitors are expected to offer future search opportunities.
If advanced aliens don't use radio, what overlooked clues could reveal their technology in these interstellar objects?
With more interstellar visitors coming, how will we ever distinguish a natural comet from a disguised alien probe?
SETI’s Search for Alien Signals from Interstellar Comet 3I/ATLAS: Results, Methods, and Lessons from a Null Detection
Overview
In July 2025, a team at the SETI Institute conducted a focused search for alien signals on the interstellar comet 3I/ATLAS, aiming to test how well modern astronomical instruments can detect signs of extraterrestrial intelligence. The results, published in June 2026, showed that current technology is effective and realistic for identifying potential technosignatures. This success highlights major advancements in both instruments and analysis methods. The study also emphasizes the importance of ongoing, broad searches for technosignatures, demonstrating that even unexpected objects like 3I/ATLAS can provide valuable opportunities in the search for extraterrestrial life.