By Claire Bradshaw

How would you feel if, after many decades of searching, we finally found signs of extraterrestrial intelligence?

Would you be consumed by wonder and excitement, or does the thought of making contact with an unknown life force somewhere out there in the universe fill you with fear and trepidation?

And what impact would this discovery have on us collectively – would it unite us or divide us here on Earth?

“Maybe the search for extraterrestrials actually tells us more about ourselves than anything else,” says world-renowned astronomer and deputy executive director of the International Centre for Radio Astronomy Research, Professor Steven Tingay, who has been pondering these and other weighty existential questions in the course of his research.

Tingay and his CSIRO colleague Dr Chenoa Tremblay have been involved in the deepest and broadest search yet for signs of alien life, thanks to the capabilities offered by the Murchison Widefield Array (MWA) – the highly sensitive, low frequency radio telescope with a fantastically wide field of view that is supporting a trove of new scientific endeavours from its whisper-quiet location in inland Western Australia.

So far, no signals have been detected to suggest we are not alone. But with the MWA now allowing much-expanded searches to be conducted alongside other astrophysical investigations, the search for extraterrestrial intelligence – commonly referred to as SETI – is definitely ramping up.

For example, it will no doubt add to fresh questions about our cosmic exclusivity generated by NASA’s latest mission to Mars, where the Perseverance rover is collecting rock and soil samples that will be probed for signs of ancient microbial life.

In 2018, the MWA was used to scan part of the Vela constellation, known to cover at least 10 million star systems. Within this field are six known exoplanets: planets that orbit around other stars, like the Earth orbits around the Sun, that could potentially offer the right conditions for hosting life. Through this and two previous surveys, Tingay and Tremblay examined 75 known exoplanets, searching for narrow-band signals consistent with radio transmissions from intelligent civilisations, with a further 144 exoplanets examined in research to be published soon.

Professor Steven Tingay, an expert in the Search for Extraterrestrial Intelligence.

Curtin University’s Professor Steven Tingay is one of the world’s most foremost experts in the search for extraterrestrial intelligence.

Fortuitously, the MWA allows the search for extraterrestrial intelligence to piggyback onto science that is already taking place – offering, as Tingay describes it, “two bits of science for one”. As part of her PhD research, Chenoa was using the radio telescope to observe molecular signatures from stars, gas and dust in our galaxy in the hopes of detecting the complex molecules that are the precursor to life. The pair then realised that these data could be simultaneously used for the search for radio signals from advanced civilisations.

“It’s a very high-return, low-effort route at this stage, which means that if you strike it lucky it hasn’t really cost you all that much along the way,” explains Tingay. “So that’s almost a perfect scenario for science.”

So what exactly are they looking for in their MWA surveys?

“We’re not one hundred per cent sure,” admits Tremblay.

“It’s like asking a toddler to go and find an object in the house and they very excitedly go and run around and look under the couch and then come back with big eyes and go, ‘What does it look like?’

“In general, we’re looking for intense signals that show up in very narrow wavelength ranges, and it could be anywhere within the electromagnetic spectrum. We use models from our understanding of the cosmos and what the signals have looked like so far to narrow down the search.

“The benefit of looking at lower radio frequencies or very long wavelengths is that they pass through the Earth’s atmosphere so we can build ground-based telescopes. They are travelling through dust and gas that might be within the galaxy. So that means we can probe much further across larger distances than if we’re looking at much higher energies or smaller wavelengths.”

While the 2018 survey was far more comprehensive than ever before, Tingay is keen to point out that it was still just a drop in the ocean.

“Our galaxy contains billions and billions of stars, so 10 million out of multiple billions is a very small fraction,” he explains.

“If that entire search space was represented by the Earth’s oceans, we’re talking about searching about a swimming pool’s worth of water out of the ocean. Having said that, what we did was a hundred times better than anyone had done previously – and the previous best was also us!

Murchison Widefield Array antennas.

The Murchison Widefield Array in outback WA has twice completed the deepest and broadest search for signs of extraterrestrial intelligence.

“So what we’re doing is proving up techniques that will allow us to go further and deeper as we develop more powerful telescopes. And the next step in that progression is the Square Kilometre Array.”

The MWA is effectively the warm-up act for the Square Kilometre Array, which has started its construction phase in Western Australia and South Africa, following more than a decade of design and engineering work by hundreds of experts from more than a dozen countries.

This global mega science project will deliver the two largest and most complex networks of radio telescopes ever built, designed to unlock some of the most fascinating secrets of our Universe – and it no doubt has SETI enthusiasts very, very excited.

Asked to sum up his own reaction should this new frontier of astronomy confirm signs of extraterrestrial intelligence sometime soon, Tingay is quick to respond: “I’ll rush to the telescope to get more data!”

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John Curtin Distinguished Professor Steven Tingay is the Deputy Executive Director of the International Centre for Radio Astronomy Research (ICRAR) and leads its Curtin University node. He is also the director of the Murchison Widefield Array.  Professor Tingay is an internationally renowned expert in astronomy and astrophysics and his research encompasses building and using radio telescopes, as well as astrophysical interpretation. He has been at the forefront of some of the fundamental advancements made possible by the MWA, including the search for the first stars 13 billions years ago as well as the search for extraterrestrial life. Professor Tingay was named the joint winner of the Scientist of the Year award at the 2020 Western Australian Premier’s Science Awards.

Dr Chenoa Tremblay completed her PhD in Physics at Curtin University in 2018. She is now a Postdoctoral Researcher with CSIRO (Australia’s National Science Agency) studying the magnetic fields and chemistry of stars and star-forming regions. For her thesis, she used the Murchison Widefield Array to look for molecules with low energy transmissions in interstellar space, which also helped set the limits on the first low-frequency search for extraterrestrial signals towards known exoplanets. Previously, Dr Tremblay was a special projects manager with Australian-based mineral analysis company MinAnalytical where she developed new technologies and software for laboratories supporting the mining industry.