For decades, we’ve been looking to the skies for any sign of aliens – but it turns out we may have been missing attempts at contact.
A new study has cast doubt on our radio signal detection methods, arguing that ‘space weather’ could be distorting incoming transmissions.
Until now, most experiments have focused on identifying spikes in radio frequency – signals unlikely to be produced by any other natural processes in space.
But experts have highlighted an overlooked complication.
Even if an extraterrestrial transmitter produces a perfectly narrow radio signal, it may not remain narrow by the time it leaves its home star’s atmosphere.
This distortion, which happens near the point of origin, can ‘smear’ the signal’s frequency, meaning it can be missed by our detectors that are primed to search for more focused radio waves.
‘Searches are often optimized for extremely narrow signals,’ Dr Vishal Gajjar, astronomer at the SETI Institute and lead author of the paper, said.
‘If a signal gets broadened by its own star’s environment, it can slip below our detection thresholds, even if it’s there, potentially helping explain some of the radio silence we’ve seen in technosignature searches.’
For their study, the team analysed radio transmissions from our own spacecraft in the solar system.
Using measurements from probes, they worked out how turbulent plasma released from stars – such as the Sun – affects radio signals.
Hellbound and Down 