3I/ATLAS technosignatures – A search for artificial “technosignatures” linked to interstellar object 3I/ATLAS found none. After the comet entered our solar system last year, astronomers tracked it with the Allen Telescope Array, checking for narrowband radio signals across the full frequ
The interstellar visitor arrived with a headline speed—about 137,000 miles per hour—and with it came a question that reaches far beyond planetary science: could Comet 3I/ATLAS carry an unnatural signature?
When astronomers first discovered 3I/ATLAS in July 2025. researchers noted it was only the third known interstellar object to enter our solar system. As it moved in, the icy body revealed a chemistry that sounded anything but engineered. Observations showed it was “bursting with methanol. ” and its coma—the vapor envelope that forms as the icy object nears the sun—was full of frozen carbon dioxide. Taken together, the evidence pointed to a natural origin.
Even so, some scientists were looking for technosignatures, especially in the radio band. The search wasn’t happening in a vacuum. Sofia Sheikh. a research scientist at the SETI Institute. said in a statement that “eventually. our own Voyager spacecraft will be extraterrestrial artifacts in other stellar systems. ” referring to the twin interstellar probes NASA launched in 1977. If other civilizations ever find our instruments. she argued. we’ll need to understand the natural distribution of interstellar objects so that genuine anomalies don’t get buried.
To test whether 3I/ATLAS held anything artificial. Sheikh and colleagues used the Allen Telescope Array. tracking the comet and looking for narrowband radio signals—“the kind that can only come from technology.” After analyzing several hours of data across the full frequency range of the ATA. Sheikh said the team did not see any signals. or technosignatures. associated with 3I/ATLAS.
Sheikh said she wasn’t surprised. “All of the evidence that the global scientific community had found before. during. and after our observations indicated that 3I/ATLAS was an icy rock from another solar system—extremely cool from a planetary science perspective. but not in any way a technological artifact. ” she said.
None of that made the work feel like a dead end. Null results still tell scientists what not to chase, and Sheikh emphasized that the practice matters. In her view, finding no technosignatures is part of preparing for the next interstellar object.
“By better understanding natural objects like 3I/ATLAS and practicing our methodologies on real-world events, we are better prepared to observe and analyze other interstellar objects, including potentially artificial objects, in the future,” she said.
The new study was published on Wednesday in the Astronomical Journal.
In the end, 3I/ATLAS still looks like what it appears to be: an icy interloper from another solar system, fast enough to be unforgettable and chemically active enough to be scientifically rich. For now, the sky’s message remains the same—natural, not technological.
3I/ATLAS interstellar comet technosignatures SETI Allen Telescope Array methanol frozen carbon dioxide radio signals Astronomical Journal Voyager