A new study from the SETI Institute reveals that stellar “space weather” could hinder the detection of extraterrestrial radio signals. While conventional searches look for ultra-narrow frequency spikes – indicators of artificial origin – this research shows that such signals may be broadened before they ever leave their home star system.

Plasma turbulence and stellar activity, including coronal mass ejections, can distort radio waves near their source, spreading the signal’s power across a wider range of frequencies. This “smearing” of “space weather” effect can push transmissions below the detection thresholds of standard search pipelines.

Dr. Vishal Gajjar, an astronomer at the SETI Institute and lead author of the paper, said that SETI searches are often optimized for extremely narrow signals. He noted that if a signal gets broadened by its own star’s environment, it can slip below detection thresholds, potentially helping explain some of the radio silence observed in technosignature searches. Using radio transmissions from spacecraft in our solar system, the team calibrated how turbulent plasma affects narrowband signals and applied this to diverse stellar environments. Their findings suggest that M-dwarf stars – which make up roughly 75% of stars in the Milky Way – are most likely to broaden signals, calling for more flexible search strategies.

Co-author Grayce C. Brown, a research assistant at the SETI Institute, explained that by quantifying how stellar activity can reshape narrowband signals, researchers can design searches that are better matched to what actually arrives at Earth, rather than just what might be transmitted. Supported by the SETI Institute’s STRIDE program, the study underscores the need for adaptive technosignature detection methods.

For more details, read the full adrticle by SETI Institute.