A new study by researchers at the SETI Institute suggests that stellar “space weather” could make radio signals from extraterrestrial intelligence harder to detect. Stellar activity and plasma turbulence near a transmitting planet can broaden an otherwise ultra-narrow signal, spreading its power across more frequencies and making it more difficult to detect in traditional narrowband searches. The paper is published in The Astrophysical Journal.
For decades, many SETI experiments have focused on identifying spikes in frequency—signals unlikely to be produced by natural astrophysical processes. But the new research highlights an overlooked complication: even if an extraterrestrial transmitter produces a perfectly narrow signal, it may not remain narrow by the time it leaves its home system.
In most technosignature searches, scientists account for distortions that happen as radio waves travel across interstellar space. This study focuses on what can happen closer to the source. Plasma density fluctuations in stellar winds, as well as occasional eruptive events such as coronal mass ejections, can distort radio waves near their point of origin, effectively “smearing” the signal’s frequency and reducing the peak strength that search pipelines rely on.
