One Hour of Listening: How the SKA Could Detect an Alien Civilization in Its First Hour of Operation
Featured image: Artist’s impression of the Square Kilometre Array dish core in South Africa; credit: SKA Project Development Office / XILOSTUDIOS (CC BY-SA 3.0)
The Square Kilometre Array (SKA) is still years away from full operations, but astronomers are already making a bold case for its most profound application: finding aliens. A new book chapter published by Dr. Chenoa Tremblay and a team of two dozen SETI researchers argues that the SKA’s unprecedented sensitivity could detect the unintentional radio leakage of an advanced civilization from four light-years away in just one hour of observing time.
That distance, the distance to the nearest star system, means the SKA could effectively survey every star in our immediate cosmic neighborhood for signs of technology.
> “One hour of observational time on the SKA itself would be enough to pick up signals from the equivalent of a modern-day mobile phone network similar to what we currently have on Earth from an exoplanet four light years away,” the researchers write.
This is not about scanning for alien civilizations to beam a message our way. It is about detecting the noise they produce just by existing: radar, satellite communications, industrial emissions, and other “leakage radiation” that any technological civilization would radiate into space. For the first time, SETI has a shot at finding neighbors who are not trying to be found.
From Needles to Haystacks
Traditional SETI has relied on the assumption that alien civilizations would deliberately transmit narrowband beacons, signals compressed into a tiny slice of the radio spectrum to stand out against natural astrophysical noise. Pioneers like Frank Drake justified this approach by arguing that such a narrow signal would be a clear sign of intent. But it also meant that researchers could only find signals intentionally directed at Earth.
The SKA shatters that limitation. With a collecting area of one square kilometer spread across two continents (Australia for low-frequency arrays, South Africa for mid-band dishes), its sensitivity is an order of magnitude beyond anything that has come before. Where the Green Bank Telescope or the Allen Telescope Array can scan a handful of stars at a time, the SKA can monitor millions.
“We have not looked well enough yet to say much so far,” Steve Croft of the SETI Institute and UC Berkeley has said. The SKA changes that equation fundamentally.
Piggybacking on the Universe
One of the most elegant aspects of the proposed SETI strategy is that it does not require dedicated observing time. The team plans to build a parallel data pipeline that copies data already being collected for other science (supernova surveys, pulsar timing, cosmology) and runs it through SETI analysis in real time. No telescope time needs to be diverted; every observation becomes a potential alien search.
The data will be cross-referenced against large stellar catalogs such as Gaia to evaluate promising sources. Machine learning algorithms, trained to distinguish anthropogenic radio frequency interference (RFI) from genuine extraterrestrial signals, will filter the torrent of incoming data.
Sofia Sheikh of the SETI Institute led a 2025 study estimating that the SKA could detect signals like those broadcast by NASA’s Deep Space Network from 65 light-years away, and a deliberate Arecibo-style message from 12,000 light-years away. Phase 1 of the SKA, operating at roughly 10 percent of its final collecting area, will already be at least five times more sensitive than any existing single-dish facility.
The Challenge of a Cosmic Haystack
The SKA’s biggest asset is also its biggest problem. The array produces petabytes of data, and storing every candidate signal for later analysis is not practical. The SETI team is developing AI-based RFI rejection algorithms and very long baseline interferometry (VLBI) techniques to distinguish genuine signals from Earth-based interference by their spatial signature.
“One could argue that we have only searched the equivalent of a small swimming pool compared to Earth’s oceans,” researchers have noted about the current state of SETI. The SKA expands that search volume dramatically.
Even a null result would be scientifically valuable. “But even a negative result in this case would be a huge data point for science more generally,” the chapter notes. If the SKA scans millions of stars and finds nothing, it places the most stringent upper limits ever on the prevalence of technological civilizations in the galaxy.
What Comes Next
The SKA’s full science operations are expected to begin around 2029, with initial data flowing in as early as 2027. The chapter, published as part of the “Advancing Astrophysics with the SKA II” conference series (arXiv:2606.27565), outlines the specific data products and resolution requirements needed to make the SETI search work.
For the team of two dozen astronomers, astrophysicists, and technosignature specialists who co-authored the chapter, the timeline is almost irrelevant. The capability itself represents a generational leap.
“The SKA’s singular capabilities will render it an indispensable instrument for the rapid identification and follow-up characterization of promising technosignature candidates,” the authors write. Put simply: the world’s largest telescope is about to become the world’s best alien hunter.