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SETI experiment succeeds: fails to find aliens

‘It’s only a model’

If there are sentient aliens on the “habitable zone” planet circling Gliese 581, they’re not calling out to us. That’s the conclusion of Western Australian astronomers, who have released the results of a targeted SETI-hunt using Very Long Baseline Interferometry (VLBI) to sniff out radio signals from the distant red dwarf.

Even without the aliens, however, the experiment was a success. In this paper, soon to be published in the Astronomical Journal, the Curtin University researchers point out that their techniques demonstrate the suitability of VLBI for targeted SETI work – providing a model for how data collected by the South African/Australian Square Kilometer Array could be filtered for “lifelike” signals.

That’s mainly because a VLBI instrument has a key advantage over using a single radio-telescope: it’s easier to identify (and therefore remove) man-made radio frequency interference. Since VLBI uses multiple collectors (in this case, the Parkes radiotelescope, the Mopra array near Narrabri, and the nearby Australia Telescope Compact Array), local interference won’t appear at all antennae at the same time. On the other hand, signals from a distant planet like those circling Gliese 581 will arrive simultaneously at all the instruments.

The Curtin analysis, used 20 hours’ of observations from 2007, looking at the frequency pairs 1,262/1,312 MHz, 1,362/1,412 MHz and 1,462/1,512 MHz, with the data analysed using the AIPS package, along with numpy and the ParselTongue scripting language.

That analysis revealed more than 200 candidate signals; regrettably, all of them came from Optus and Inmarsat satellites. However, as the paper states, this proof of concept demonstrates that “VLBI is ideal for targeted SETI”. ®

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