June 3, 2026, Mountain View, CA — Scientists at the SETI Institute searched for technological signals from 3I/ATLAS, the third interstellar object observed in our Solar System. Using the Allen Telescope Array (ATA) at the Hat Creek Radio Observatory in Northern California, the team scanned a wide range of radio frequencies for signs of extraterrestrial technology and found none, as expected based on other astronomical observations showing that the object exhibits natural comet-like composition and behavior.
A Rare Interstellar Visitor
Discovered in July 2025, 3I/ATLAS is the third confirmed object from another star system to enter our Solar System, after 1I/'Oumuamua and 2I/Borisov. Its interstellar origin makes 3I/ATLAS a rare opportunity to study material from another stellar system and better understand how planetary systems form and evolve. While observations strongly indicate that 3I/ATLAS is a natural object, interstellar visitors are also compelling technosignature targets because an artificial object—however unlikely—could represent detectable extraterrestrial technology and potentially provide the first evidence of life beyond Earth.
"Eventually, our own Voyager spacecraft will be extraterrestrial artifacts in other stellar systems," said Dr. Sofia Sheikh , lead author on the paper. "Given that, it is important that we understand the natural distribution of interstellar objects so that we will be able to identify any anomalies that could one day be signs of an artificial interstellar object." The team observed 3I/ATLAS for more than seven hours with the ATA, covering 1 to 9 gigahertz. This broad range allows scientists to search for narrowband radio signals, which are not produced by in nature and would be evidence of technology.
The team identified nearly 74 million narrowband signals. After removing human interference and filtering for signals matching 3I/ATLAS's movement, only about 200 remained for review. All traced back to technology on the surface of the Earth or our own Earth-orbiting satellites.
What Scientists Found
While no technosignatures were found, the study sets new constraints reinforcing that 3I/ATLAS is a natural object. The observations place upper limits on the power of any radio transmitter on or near 3I/ATLAS, ruling out signals stronger than about 10–110 watts, approximately the power of a household appliance, over the detected frequencies.
"The results from 3I/ATLAS show how realistic it is to detect a signal with the technology we have today," said Valeria Garcia Lopez, co-author. "That is why it is important to keep searching for technosignatures, even from objects we might not expect to have signals."
The study also demonstrates the ATA's rapid response to new interstellar objects. Observations began less than a day after 3I/ATLAS was announced, showing the system's agility.
Besides searching for signs of intelligence, the observation of interstellar objects also help scientists learn about the natural properties of interstellar objects as they travel through our Solar System.
As more interstellar objects are discovered, each offers a new opportunity to probe the cosmos for technosignatures, advancing our understanding of both natural and possible technological phenomena beyond our Solar System.
DOI: 10.3847/1538-3881/ae6651
About the SETI Institute
Founded in 1984, the SETI Institute is a non-profit, multi-disciplinary research and education organization whose mission is to lead humanity's quest to understand the origins and prevalence of life and intelligence in the Universe and to share that knowledge with the world. Our research encompasses the physical and biological sciences and leverages expertise in data analytics, machine learning and advanced signal detection technologies. The SETI Institute is a distinguished research partner for industry, academia and government agencies, including NASA and NSF.
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SETI Institute
