Chinese FAST Radio Telescope Detects SETI Candidate Signal

SCANALYZER Tracking with Closeups
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The signal, from the direction of star Kepler-438, a red dwarf with a confirmed exoplanet in the star’s habitable zone, passed the initial discrimination filters but, due to its polarisation, is suspected to be radio frequency interference, possibly from an instrument on the telescope. The detection is reported in the preprint “The most sensitive SETI observation by multi-beam coincidence matching strategy towards exoplanet systems”. Here is the abstract.

`Are we alone?’ The Search for Extra-Terrestrial Intelligence (SETI) aims to answer this profound question. Apart from examining environments in our solar system and detecting biosignatures in exoplanet atmospheres, SETI is another main approach to search for life beyond Earth by detecting technosignatures indicative of extra-terrestrial intelligence (ETI), such as engineering radio signals. Massive efforts have been made by SETI scientists using radio telescopes around the world. Though some candidate signals were detected, none of them has been confirmed as an ETI technosignature so far. Most targeted SETI observations performed in recent years use on-off strategy to distinguish signals transmitted from celestial bodies from radio frequency interference (RFI) generated near the ground. Here we report a SETI campaign employing another SETI observation strategy, multi-beam coincidence matching (MBCM), at the Five-hundred-meter Aperture Spherical radio Telescope (FAST) towards 33 currently discovered planetary systems, searching for narrow band drifting signals at a band of 1.05-1.45 GHz. Our observations achieve an unprecedented sensitivity with a minimum Equivalent Isotropic Radiated Power (EIRP) of 1.5 \times 10^{9} ~\text{W}. We process the data of two orthogonal polarization separately, aiming to discriminate instrumental RFI signals. A particular signal at 1140.604 MHz from the observation towards Kepler-438 passes our initial selection criteria. Although we have not yet determined the exact cause of this signal, its polarization characteristic suggests that it is most likely to be attributed to RFI. In spite of this, our work verifies that compared to single-beam on-off strategy, MBCM greatly improves both time efficiency and radio frequency interference (RFI) identification effectiveness of targeted SETI observations.

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Wow! Intelligent life on … Planet Earth. China has built a 1,500 foot radio telescope (who knew?) – and has managed to avoid the auto-destruct problem that afflicted the US version in Puerto Rico. Speaking purely personally, I find that to be more germane than the issue of whether or not there is intelligent life light-years from Earth.

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My bet is on PIM - passive intermodulation - which is a fairly well understood form of “weird” RF interference that is often hard to pinpoint or solve.

The canonical PIM root cause is the storied “rusty bolt” that - when placed at an appropriate distance as a multiple of the wavelength of the signal - can act as a non-linear source producing so-called interfering signals at frequencies that are linear combinations of multiple bands in use.

I speculate that with SETI receive sensitivity. even something like a cell phone within a reasonable distance from the receiver could mix multiple signals that would be “picked up” by the “rusty bolt” and then land into the receive band of the dish.

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Reminds me of two anecdotes attributed to Zhou Enlai: when asked what he thought of the effects of the French Revolution, his alleged response was “too early to tell”.

And apparently - though I might misattribute this one - when a reporter asked him what he thought of European civilization he said “it would be a good idea”

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